lnu.sePublications
Change search
Refine search result
1234 1 - 50 of 156
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Andersson, Martin O.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tamba, Paula
    Inst Diag & Anim Hlth, Romania.
    Stefanache, Mircea
    PAUMI VET Private Vet Clin, Romania.
    Radbea, Gabriel
    Sal Vet Private Vet Clin, Romania.
    Frangoulidis, Dimitrios
    Bundeswehr Inst Microbiol, Germany.
    Tomaso, Herbert
    Friedrich Loeffler Inst, Germany.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dobler, Gerhard
    Bundeswehr Inst Microbiol, Germany;German Ctr Infect Res DZIF Partner Munich, Germany.
    Chitimia-Dobler, Lidia
    Inst Diag & Anim Hlth, Romania;Bundeswehr Inst Microbiol, Germany;German Ctr Infect Res DZIF Partner Munich, Germany.
    Molecular survey of neglected bacterial pathogens reveals an abundant diversity of species and genotypes in ticks collected from animal hosts across Romania2018In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 11, article id 144Article in journal (Refereed)
    Abstract [en]

    Background: Ticks are transmitting a wide range of bacterial pathogens that cause substantial morbidity and mortality in domestic animals. The full pathogen burden transmitted by tick vectors is incompletely studied in many geographical areas, and extensive studies are required to fully understand the diversity and distribution of pathogens transmitted by ticks. Results: We sampled 824 ticks of 11 species collected in 19 counties in Romania. Ticks were collected mainly from dogs, but also from other domestic and wild animals, and were subjected to molecular screening for pathogens. Rickettsia spp. was the most commonly detected pathogen, occurring in 10.6% (87/824) of ticks. Several species were detected: Rickettsia helvetica, R. raoultii, R. massiliae, R. monacensis, R. slovaca and R. aeschlimannii. A single occurrence of the zoonotic bacterium Bartonella vinsonii berkhoffii was detected in a tick collected from a dog. Anaplasma phagocytophilum occurred in four samples, and sequences similar to Anaplasma marginale/ovis were abundant in ticks from ruminants. In addition, molecular screening showed that ticks from dogs were carrying an Ehrlichia species identical to the HF strain as well as the enigmatic zoonotic pathogen "Candidatus Neoehrlichia mikurensis". An organism similar to E. chaffeensis or E. muris was detected in an Ixodes ricinus collected from a fox. Conclusions: We describe an abundant diversity of bacterial tick-borne pathogens in ticks collected from animal hosts in Romania, both on the level of species and genotypes/strains within these species. Several findings were novel for Romania, including Bartonella vinsonii subsp. berkhoffii that causes bacteremia and endocarditis in dogs. "Candidatus Neoehrlichia mikurensis" was detected in a tick collected from a dog. Previously, a single case of infection in a dog was diagnosed in Germany. The results warrant further studies on the consequences of tick-borne pathogens in domestic animals in Romania.

  • 2.
    Andersson, Martin O.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tamba, Paula
    Inst Diag & Anim Hlth, Romania.
    Stefanache, Mircea
    PAUMI VET Private Vet Clin, Romania.
    Radbea, Gabriel
    Sal Vet Private Vet Clin, Romania.
    Rubel, Franz
    Univ Vet Med Vienna, Austria.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dobler, Gerhard
    German Ctr Infect Res DZIF Partner Munich, Germany.
    Chitimia-Dobler, Lidia
    Inst Diag & Anim Hlth, Romania ; German Ctr Infect Res DZIF Partner Munich, Germany.
    Babesia, Theileria, and Hepatozoon species in ticks infesting animal hosts in Romania2017In: Parasitology Research, ISSN 0932-0113, E-ISSN 1432-1955, Vol. 116, no 8, p. 2291-2297Article in journal (Refereed)
    Abstract [en]

    Babesia spp., Theileria spp., and Hepatozoon spp. are tick-transmitted apicomplexan parasites that cause several important diseases in animals. To increase current knowledge about the diversity of tick-transmitted pathogens in Romania, we investigated the occurrence of Babesia spp., Theileria spp., and Hepatozoon spp. in a wide range of tick species infesting animal hosts. We collected 852 ticks from 10 different animal species from 20 counties in Romania. The assessment was based on detection of parasite DNA by PCR. Five different apicomplexan parasite species were detected; among them three different species of Babesia: B. canis, B. microti, and B. ovis. Hepatozoon canis was the most frequently detected parasite, found predominately in Ixodes ricinus ticks collected from domestic dogs. It was also detected in I. ricinus collected from goat, fox, and cat. Furthermore, H. canis was found in Haemaphysalis punctata and Haemaphysalis concinna ticks. In addition, Theileria buffeli was detected in Rhipicephalus bursa ticks collected from cattle.

  • 3.
    Andersson, Martin O.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tamba, Paula
    Institute for Diagnosis and Animal Health, Romania.
    Stefanache, Mircea
    PAUMI-VET Private Veterinary Clinics, Romania.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Dobler, Gerhard
    German Center for Infection Research, Germany.
    Chitimia-Dobler, Lidia
    German Center for Infection Research, Germany.
    Canine tick-borne diseases in pet dogs from Romania2017In: Parasites & Vectors, ISSN 1756-3305, E-ISSN 1756-3305, Vol. 10, article id 2092Article in journal (Refereed)
    Abstract [en]

    Background: Tick-borne diseases are of substantial concern worldwide for animals as well as humans. Dogs have been a human companion for millennia, and their significant impact on human life renders disease in dogs to be of great concern. Tick-borne diseases in dogs represent a substantial diagnostic challenge for veterinarians in that clinical signs are often diffuse and overlapping. In addition, co-infections with two or more pathogens enhance this problem further. Molecular methods are useful to disentangle co-infections and to accurately describe prevalence and geographical distribution of tick-borne diseases. At this point, this information is lacking in many areas worldwide. Romania is one such area, where prevalence and distribution of several important pathogens need to be further investigated. To address this, we screened blood samples from 96 sick dogs with molecular methods for eight different pathogens including Babesia spp., Theileria spp., Hepatozoon spp., Anaplasma spp., Ehrlichia spp., "Candidatus Neoehrlichia mikurensis", Mycoplasma spp., and Borrelia spp. Results: As many as 45% (43/ 96) of the dogs in the study were infected with protozoan parasites. Babesia canis was the most frequent of these (28 infected dogs), whereas Hepatozoon canis was detected in 15% (14/ 96) and Babesia gibsoni was found in a single sample. Bacterial infection with Mycoplasma spp. occurred in 18% (17/ 96) of the sampled dogs. Obtained bacterial sequences revealed the occurrence of two species: Mycoplasma canis and "Candidatus Mycoplasma haematoparvum". In several cases co-infection with protozoan parasites and Mycoplasma sp. were detected. All dogs were negative for Anaplasma spp., Ehrlichia spp., "Ca. Neoehrlichia mikurensis", and for Borrelia spp. Conclusions: The results from the present study reinforce the notion that Babesia canis is an important pathogen in the Romanian dog population. However, more surprisingly, another protozoan species, H. canis, seems to be infecting dogs to a larger extent than previously recognized in Romania. Well-known tick-borne bacterial disease agents such as Anaplasma spp. and Borrelia spp. were not detected. In contrast, less wellstudied bacteria such as hemotropic Mycoplasma spp. were detected frequently. Moreover, co-infection might aggravate disease and complicate diagnosis and should be further studied in dogs.

  • 4.
    Andersson, Martin O.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Vichova, Bronislava
    Slovak Acad Sci, Slovakia.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Krzyzanowska, Sandra
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Karlsson, Maria E.
    Swedish University of Agricultural Sciences.
    Co-infection with Babesia divergens and Anaplasma phagocytophilum in cattle (Bos taurus), Sweden2017In: Ticks and Tick-borne Diseases, ISSN 1877-959X, E-ISSN 1877-9603, Vol. 8, no 6, p. 933-935Article in journal (Refereed)
    Abstract [en]

    Babesiosis is a severe disease in cattle worldwide. In Europe, the main causative agent of bovine babesiosis is Babesia divergens. In some areas, this species is reported to have declined or even disappeared, and its etiological role overtaken by other piroplasmid species. Moreover, co-infection with other tick-transmitted pathogens can be expected to complicate diagnosis in cattle. Hence, molecular identification of the causative agent of babesiosis should be a priority. Therefore, samples from 71 domestic cattle, 39 with clinical signs of babesiosis and 32 without, from southern Sweden were screened for Babesia spp. and Anaplasma spp. using molecular methods Babesia divergens was detected in 38 of the samples, and Anaplasma phagocytophilum in 17. Co-infections with both pathogens were frequent, occurring in 18% of the animals with a B. divergens infection. The possibility of co-infection should be considered in diagnosis and treatment of bovine babesiosis.

  • 5.
    Ardiles-Villegas, Karen
    et al.
    Universidad de Concepción, Chile.
    González-Acuña, Daniel
    Universidad de Concepción, Chile.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Uppsala University.
    Hernandez, Jorge
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Uppsala University.
    Antibiotic resistance patterns in fecal bacteria isolated from Christmas shearwater (Puffinus nativitatis) and masked booby (Sula dactylatra) at remote Easter Island2011In: Avian diseases, ISSN 0005-2086, E-ISSN 1938-4351, Vol. 55, no 3, p. 486-489Article in journal (Refereed)
    Abstract [en]

    Antibiotic use and its implications have been discussed extensively in the past decades. This situation has global consequences when antibiotic resistance becomes widespread in the intestinal bacterial flora of stationary and migratory birds. This study investigated the incidence of fecal bacteria and general antibiotic resistance, with special focus on extended spectrum beta-lactamase (ESBL) isolates, in two species of seabirds at remote Easter Island. We identified 11 species of bacteria from masked booby (Sula dactylatra) and Christmas shearwater (Puffinus nativitatis); five species of gram-negative bacilli, four species of Streptococcus (Enterococcus), and 2 species of Staphylococcus. In addition, 6 types of bacteria were determined barely to the genus level. General antibiotic susceptibility was measured in the 30 isolated Enterobacteriaceae to 11 antibiotics used in human and veterinary medicine. The 10 isolates that showed a phenotypic ESBL profile were verified by clavulanic acid inhibition in double mixture discs with cefpodoxime, and two ESBL strains were found, one strain in masked booby and one strain in Christmas shearwater. The two bacteria harboring the ESBL type were identified as Serratia odorifera biotype 1, which has zoonotic importance. Despite minimal human presence in the masked booby and Christmas shearwater habitats, and the extreme geographic isolation of Easter Island, we found several multiresistant bacteria and even two isolates with ESBL phenotypes. The finding of ESBLs has animal and public health significance and is of potential concern, especially because the investigation was limited in size and indicated that antibiotic-resistant bacteria now are distributed globally.

  • 6.
    Atterby, Clara
    et al.
    Uppsala University.
    Mourkas, Evangelos
    Uppsala University;Univ Bath, UK.
    Meric, Guillaume
    Univ Bath, UK.
    Pascoe, Ben
    Univ Bath, UK;MRC CLIMB Consortium, UK.
    Wang, Helen
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Sheppard, Samuel K.
    Univ Bath, UK;MRC CLIMB Consortium, UK.
    Olsen, Björn
    Uppsala University.
    Jarhult, Josef D.
    Uppsala University.
    Ellström, Patrik
    Uppsala University.
    The Potential of Isolation Source to Predict Colonization in Avian Hosts: A Case Study in Campylobacter jejuni Strains From Three Bird Species2018In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 591Article in journal (Refereed)
    Abstract [en]

    Campylobacter jejuni is the primary cause of bacterial gastroenteritis worldwide, infecting humans mostly through consumption of contaminated poultry. C. jejuni is common in the gut of wild birds, and shows distinct strain-specific association to particular bird species. This contrasts with farm animals, in which several genotypes co-exist. It is unclear if the barriers restricting transmission between host species of such specialist strains are related to environmental factors such as contact between host species, bacterial survival in the environment, etc., or rather to strain specific adaptation to the intestinal environment of specific hosts. We compared colonization dynamics in vivo between two host-specific C. jejuni from a song thrush (ST-1304 complex) and a mallard (ST-995), and a generalist strain from chicken (ST-21 complex) in a wild host, the mallard (Anas platyrhynchos). In 18-days infection experiments, the song thrush strain showed only weak colonization and was cleared from all birds after 10 days, whereas both mallard and chicken strains remained stable. When the chicken strain was given 4 days prior to co-infection of the same birds with a mallard strain, it was rapidly outcompeted by the latter. In contrast, when the mallard strain was given 4 days prior to co-infection with the chicken strain, the mallard strain remained and expansion of the chicken strain was delayed. Our results suggest strain-specific differences in the ability of C. jejuni to colonize mallards, likely associated with host origin. This difference might explain observed host association patterns in C. jejuni from wild birds.

  • 7.
    Avril, Alexis
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Grosbois, Vladimir
    CIRAD, France.
    Latorre-Margalef, Neus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Univ Georgia, USA.
    Gaidet, Nicolas
    CIRAD, France.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Björn
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Capturing individual-level parameters of influenza A virus dynamics in wild ducks using multistate models2016In: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 53, no 4, p. 1289-1297Article in journal (Refereed)
    Abstract [en]

    Disease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual-scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health. Using capture-recaptures of 3500 individual mallards Anas platyrhynchos during seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual-based mechanisms of IAV dynamics in a wild reservoir host. For most years, prevalence and risk of IAV infection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years. Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual-based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourage IAV surveillance with a multistate capture-recapture approach along the entire migratory flyway of mallards.

  • 8.
    Axelsson Olsson, Diana
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ellström, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Haemig, Paul D
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brudin, Lars
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Acanthamoeba-Campylobacter coculture as a novel method for enrichment of Campylobacter species2007In: Applied and Environmental Microbiology, Vol. 73, no 21, p. 6864-6869Article in journal (Refereed)
    Abstract [en]

    In this study, we present a novel method to isolate and enrich low concentrations of Campylobacter pathogens. This method, Acanthamoeba-Campylobacter coculture (ACC), is based on the intracellular survival and multiplication of Campylobacter species in the free-living protozoan Acanthamoeba polyphaga. Four of the Campylobacter species relevant to humans and livestock, Campylobacter jejuni, C. coli, C. lari, and C. hyointestinalis, were effectively enriched by the coculture method, with growth rates comparable to those observed in other Campylobacter enrichment media. Studying six strains of C. jejuni isolated from different sources, we found that all of the strains could be enriched from an inoculum of fewer than 10 bacteria. The sensitivity of the ACC method was not negatively affected by the use of Campylobacter-selective antibiotics in the culture medium, but these were effective in suppressing the growth of seven different bacterial species added at a concentration of 10(4) CFU/ml of each species as deliberate contamination. The ACC method has advantages over other enrichment methods as it is not dependent on a microaerobic milieu and does not require the use of blood or other oxygen-quenching agents. Our study found the ACC method to be a promising tool for the enrichment of Campylobacter species, particularly from water samples with low bacterial concentrations.

  • 9.
    Axelsson Olsson, Diana
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olofsson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ellström, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    A simple method for long-term storage Acanthamoeba species2009In: Parasitology Research, ISSN 0932-0113, E-ISSN 1432-1955, Vol. 104, no 4, p. 935-937Article in journal (Refereed)
    Abstract [en]

    We present a novel and simple technique for storing live Acanthamoeba for long periods of time. The amoebae are maintained at refrigerator temperatures in a peptone-yeast extract-glucose (PYG) medium normally used for cultivation. Using this method, we obtained survival rates of at least 4 years for Acanthamoeba polyphaga and 3 years for Acanthamoeba castellanii and Acanthamoeba rhysodes. Advantages of this storage method are: (1) it is quick and simple, (2) inexpensive, (3) does not require encystment before storage, (4) resuscitation of cysts can be achieved within a week of culture in PYG medium at 27A degrees C, and does not require co-culture with bacteria or any special equipment.

  • 10.
    Axelsson Olsson, Diana
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olofsson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Svensson, Lovisa
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ellström, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olsen, Björn
    Uppsala University Hospital.
    Campylobacter jejuni acid tolerance increases when co-incubated with amoebae2009Conference paper (Refereed)
    Abstract [en]

    Background: Although Campylobacter jejuni is a frequent cause of bacterial gastroenteritis, one of the enigmas is how thisfragile organism can survive the transit through the acid milieu of the stomach. C. jejuni is very sensitive to low pH, but cansurvive in moderately acid environment for short periods of time. We have previously shown that C. jejuni can colonize andeven replicate in different species of amoebas, thereby gaining protection from adverse environments.

    Objectives: We evaluated the effects of hydrochloric acid (HCl) on C. jejuni at various pH and time intervals, to study whetherco-cultivation with amoeba influenced C.jejuni acid tolerance. The setup was chosen to mimic the acidified milieu of the humangastrointestinal tract.

    Methods: Cultures of C. jejuni (CCUG 11284) were co-cultured with Acanthamoeba polyphaga in either PBS or tap wateracidified with HCl to pH 1, 2, 3 and 4. We also evaluated different treatments effect on campylobacter survival, by exposingsome bacterial samples to an acid shock and some to a slower acidification process.

    Results and conclusions: We show that C. jejuni can withstand pH below the normal range of survival, when co-cultured withA. polyphaga. C. jejuni co-cultured with amoebae survived acidified conditions at pH 3 for 20 hours and pH 2 for approximately5 hours. We also found a pH increase during the experiment, which correlated with campylobacter survival. These results pointto an unknown mechanism for C.jejuni to survive at low pH levels. This could be in the form of excretion of pH-increasingsubstances and simultaneous chemotaxic orientation towards a protective host. Our results could give one possible explanationto C. jejuni survival through the low pH of the gastrointestinal tract.

  • 11.
    Axelsson Olsson, Diana
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olofsson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Svensson, Lovisa
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Griekspoor, Petra
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ellström, Patrik
    University of Kalmar, School of Pure and Applied Natural Sciences. Uppsala University ; Uppsala University Hospital.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Protozoa as hosts for Campylobacter spp2009Conference paper (Refereed)
  • 12.
    Axelsson Olsson, Diana
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olofsson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Svensson, Lovisa
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Griekspoor, Petra
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ellström, Patrik
    Clinical Bacteriology, Department of Medical Sciences, Uppsala University and Uppsala University Hospital, SE-751 85 Uppsala, Sweden.
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Amoebae and algae can prolong the survival of Campylobacter species in co-culture2010In: Experimental parasitology, ISSN 0014-4894, E-ISSN 1090-2449, Vol. 126, p. 59-64Article in journal (Refereed)
    Abstract [en]

    Several species of free-living amoebae can cause disease in humans. However, in addition to the direct pathogenicity of e.g. Acanthamoebae and Naegleria species, they are recognized as environmental hosts, indirectly involved in the epidemiology of many pathogenic bacteria. Although several studies have demonstrated intracellular survival of many different bacteria in these species, the extent of such interactions as well as the implications for the epidemiology of the bacterial species involved, are largely unknown and probably underestimated. In this study, we evaluated eight different unicellular eukaryotic organisms, for their potential to serve as environmental hosts for Campylobacter species. These organisms include four amoebozoas (Acanthamoeba polyphaga, Acanthamoeba castellanii, Acanthamoeba rhysodes and Hartmanella vermiformis), one alveolate (Tetrahymena pyriformis), one stramenopile (Dinobryon sertularia), one eugoenozoa (Euglena gracilis) and one heterolobosea (Naegleria americana). Campylobacter spp. including Campylobacter jejuni, Campylobacter coli and Campylobacter lari are the most common cause of gastroenteritis in the western world. Survival and replication of these three species as well as Campylobacter hyointestinalis were assessed in co-cultures with the eukaryotic organisms. Campylobacter spp. generally survived longer in co-cultures, compared to when incubated in the corresponding growth media. The eukaryotic species that best promoted bacterial survival was the golden algae D. sertularia. Three species of amoebozoas, of the genus Acanthamoeba promoted both prolonged survival and replication of Campylobacter spp. The high abundance in lakes, ponds and water distribution networks of these organisms indicate that they might have a role in the epidemiology of campylobacteriosis, possibly contributing to survival and dissemination of these intestinal pathogens to humans and other animals. The results suggest that not only C. jejuni, but a variety of Campylobacter spp. can interact with different eukaryotic unicellular organisms.

  • 13.
    Axelsson Olsson, Diana
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Svensson, Lovisa
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olofsson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Salomon, Paulo
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ellström, Patrik
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Increase in Acid Tolerance of Campylobacter jejuni through Coincubation with Amoebae2010In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 76, no 13, p. 4194-4200Article in journal (Refereed)
    Abstract [en]

    Campylobacter jejuni is a recognized and common gastrointestinal pathogen in most parts of the world. Human infections are often food borne, and the bacterium is frequent among poultry and other food animals. However, much less is known about the epidemiology of C. jejuni in the environment and what mechanisms the bacterium depends on to tolerate low pH. The sensitive nature of C. jejuni stands in contrast to the fact that it is difficult to eradicate from poultry production, and even more contradictory is the fact that the bacterium is able to survive the acidic passage through the human stomach. Here we expand the knowledge on C. jejuni acid tolerance by looking at protozoa as a potential epidemiological pathway of infection. Our results showed that when C. jejuni cells were coincubated with Acanthamoeba polyphaga in acidified phosphate-buffered saline (PBS) or tap water, the bacteria could tolerate pHs far below those in their normal range, even surviving at pH 4 for 20 h and at pH 2 for 5 h. Interestingly, moderately acidic conditions (pH 4 and 5) were shown to trigger C. jejuni motility as well as to increase adhesion/internalization of bacteria into A. polyphaga. Taken together, the results suggest that protozoa may act as protective hosts against harsh conditions and might be a potential risk factor for C. jejuni infections. These findings may be important for our understanding of C. jejuni passage through the gastrointestinal tract and for hygiene practices used in poultry settings.

  • 14.
    Axelsson Olsson, Diana
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Broman, Tina
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Holmberg, M
    The protozoan Acanthamoeba polyphaga as a potential reservoir for Campylobacter jejuni2005In: Applied and environmental microbiology, Vol. 71 (2), p. 987-992Article in journal (Refereed)
  • 15.
    Barshep, Yahkat
    et al.
    A.P. Leventis Ornithological Research Institute, Nigeria.
    Ottosson, Ulf
    A.P. Leventis Ornithological Research Institute, Nigeria.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Hulme, Mark
    British Trust for Ornithology, UK.
    Non-breeding ecology of the Whinchat Saxicola rubetra in Nigeria2012In: Ornis Svecica, ISSN 1102-6812, Vol. 22, p. 25-32Article in journal (Refereed)
    Abstract [en]

    This study on the non-breeding ecology of the Whinchat Saxicola rubetra was conducted in central Nigeria from February through April. The core site was at Gwafan (N09°53', E08°57'), an open scrubland located 10 km east of the city of Jos. The density of Whinchats at Gwafan was 0.58 individuals/ha, almost three times the overall density around Jos. Time budget observations of colour banded Whinchats, including six birds fitted with radio-transmitters, showed that they spent 80% of their time perching, 11% foraging, 7% preening, and 2% flying. The main method of catching insects was a swoop to the ground. There was no change in perching, preening or flying time but the time some Whinchats spent foraging increased towards the end of the study period. GPS positions of individuals showed that all birds held clearly demarcated territories and defended them against neighbours. Aggressive interactions were also recorded between Whinchats and other bird species. Three birds colour-ringed in 2006 returned to the study site in 2007 and one occupied almost the same territory, indicating site fidelity.

  • 16.
    Bengtsson, Daniel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Andersson, Stina
    Ottenby Bird Observatory.
    Hellström, Magnus
    Ottenby Bird Observatory.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Age and sex determination of mallards Anas platyrhynchos in autumn2016In: Ornis Svecica, ISSN 1102-6812, Vol. 26, p. 61-81Article in journal (Refereed)
    Abstract [en]

    The mallard is a well-known and important species in migration ecology, game management,and epidemiology. Males and females are generally easily told apart, whereas ageing isproblematic, due to individual timing of the moult cycle and lack of easily defined agecriteria. From examination and photographic documentation of mallards caught within a longtermringing program at Ottenby Bird Observatory (56°12′N, 16°24′E), we describe ninecharacters of plumage and bare parts to be used for ageing mallards in autumn. The reliabilityof these characters was tested by letting experienced bird ringers determine putative age ofbirds from photos. Age determination from any single character proved to be uncertain, as therate of correctly assigned mallard photos of each character was in the range of 51-85% formales and 48-89% for females. For both sexes, the lowest figure represented post-humeralsand the highest represented tertials. Rectrices, tertial coverts, and greater coverts also hadreasonably high scores (71-85%). With all characters at hand, 91% of the males and 95% ofthe females were correctly identified to age. As young mallards, with the progress of prebreedingmoult (completed from October onwards), acquire tail and tertials identical to adults,untypical individuals are better not assigned to an age category.

  • 17.
    Bengtsson, Daniel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Avril, Alexis
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Gunnarsson, Gunnar
    Kristianstad University.
    Elmberg, Johan
    Kristianstad University.
    Söderquist, Pär
    Kristianstad University.
    Norevik, Gabriel
    Ottenby Bird Observatory.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Safi, Kamran
    Max Planck Institute for Ornitholology, Germany ; University of Konstanz, Germany.
    Fiedler, Wolfgang
    Max Planck Institute for Ornitholology, Germany ; University of Konstanz, Germany.
    Wikelski, Martin
    Max Planck Institute for Ornitholology, Germany ; University of Konstanz, Germany.
    Olsen, Björn
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Movements, Home-Range Size and Habitat Selection of Mallards during Autumn Migration2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, article id e100764Article in journal (Refereed)
    Abstract [en]

    The mallard (Anas platyrhynchos) is a focal species in game management, epidemiology and ornithology, but comparably little research has focused on the ecology of the migration seasons. We studied habitat use, time-budgets, home-range sizes, habitat selection, and movements based on spatial data collected with GPS devices attached to wild mallards trapped at an autumn stopover site in the Northwest European flyway. Sixteen individuals (13 males, 3 females) were followed for 15-38 days in October to December 2010. Forty-nine percent (SD = 8.4%) of the ducks' total time, and 85% of the day-time (SD = 28.3%), was spent at sheltered reefs and bays on the coast. Two ducks used ponds, rather than coast, as day-roosts instead. Mallards spent most of the night (76% of total time, SD = 15.8%) on wetlands, mainly on alvar steppe, or in various flooded areas (e.g. coastal meadows). Crop fields with maize were also selectively utilized. Movements between roosting and foraging areas mainly took place at dawn and dusk, and the home-ranges observed in our study are among the largest ever documented for mallards (mean = 6,859 ha; SD = 5,872 ha). This study provides insights into relatively unknown aspects of mallard ecology. The fact that autumn-staging migratory mallards have a well-developed diel activity pattern tightly linked to the use of specific habitats has implications for wetland management, hunting and conservation, as well as for the epidemiology of diseases shared between wildlife and domestic animals.

  • 18.
    Bengtsson, Daniel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Safi, Kamran
    Max Planck Institute for Ornithology, Germany;University of Konstanz, Germany.
    Avril, Alexis
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Fiedler, Wolfgang
    Max Planck Institute for Ornithology, Germany;University of Konstanz, Germany.
    Wikelski, Martin
    Max Planck Institute for Ornithology, Germany;University of Konstanz, Germany.
    Gunnarsson, Gunnar
    Kristianstad University.
    Elmberg, Johan
    Kristianstad University.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Björn
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?2016In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 3, no 2, p. 1-11, article id UNSP 150633Article in journal (Refereed)
    Abstract [en]

    The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.

  • 19.
    Bengtsson, Daniel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Avril, Alexis
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tailwind better than full tank? How weather and body condition affect departure decision in an autumn-staging migrantManuscript (preprint) (Other academic)
  • 20. Bensch, Staffan
    et al.
    Peréz Tris, Javier
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hellgren, Olof
    Linkage between nuclear and mitochondrial DNA sequences in avian malaria parasites – multiple cases of cryptic speciation?2004In: Evolution, Vol. 58, p. 1617-1621Article in journal (Refereed)
  • 21. Bensch, Staffan
    et al.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Jonzén, Niclas
    Westerdahl, Helena
    Hansson, Bengt
    Sejberg, Douglas
    Hasselquist, Dennis
    Temporal dynamics and diversity of avian malaria in a single host species2007In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 76, p. 112-122Article in journal (Refereed)
  • 22.
    Blomqvist, Maria
    et al.
    Uppsala University.
    Christerson, Linus
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Herrmann, Björn
    Uppsala University.
    Olsen, Björn
    Uppsala Univ, Dept Med Sci, Sect Infect Dis, S-75185 Uppsala, Sweden.
    Chlamydia psittaci in Swedish Wetland Birds: A Risk to Zoonotic Infection?2012In: Avian diseases, ISSN 0005-2086, E-ISSN 1938-4351, Vol. 56, no 4, p. 737-740Article in journal (Refereed)
    Abstract [en]

    Chlamydia psittaci in birds may be transmitted to humans and cause respiratory infections, sometimes as severe disease. Our study investigated the C. psittaci prevalence in migratory birds in Sweden by real-time PCR. Fecal specimens or cloacal swabs were collected from 497 birds from 22 different species, mainly mallards (Anas platyrhynchos), at two bird observatories in Sweden. DNA from C. psittaci was found in six (1.2%) birds from three different species. Five of the positive specimens were infected with four novel strains of C. psittaci, based on sequencing of partial 16S rRNA gene and ompA gene, and the sixth was indentified as a recently described Chlamydiaceae-like bacterium. Considering exposure to humans it is concluded that the risk of zoonotic infection is low.

  • 23.
    Blomqvist, Maria
    et al.
    Uppsala University.
    Christerson, Linus
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Lindberg, Peter
    Swedish Museum of Natural History.
    Helander, Björn
    Gothenburg University.
    Gunnarsson, Gunnar
    Kristianstad University.
    Herrman, Björn
    Uppsala University.
    Olsen, Björn
    Uppsala University.
    Chlamydophila psittaci in birds of prey, Sweden2012In: Infection Ecology & Epidemiology, ISSN 2000-8686, E-ISSN 2000-8686, Vol. 2, article id 8435Article in journal (Refereed)
    Abstract [en]

    Background: Chlamydia psittaci is an intracellular bacterium primarily causing respiratory diseases in birds but may also be transmitted to other animals, including humans. The prevalence of the pathogen in wild birds in Sweden is largely unknown.

    Methods: DNA was extracted from cloacae swabs and screened for C. psittaci by using a 23S rRNA gene PCR assay. Partial 16S rRNA and ompA gene fragments were sequence determined and phylogenies were analysed by the neighbour-joining method.

    Results and conclusion: The C. psittaci prevalence was 1.3% in 319 Peregrine Falcons and White-tailed Sea Eagles, vulnerable top-predators in Sweden. 16S rRNA and ompA gene analysis showed that novel Chlamydia species, as well as novel C. psittaci strains, are to be found among wild birds.

  • 24. Bonnedahl, Jonas
    et al.
    Broman, Tina
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Palmgren, Helena
    Niskanen, Taina
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    In search of human-associated bacterial pathogens in Antarctic wildlife: report from six penguin colonies regularly visited by tourists2005In: Ambio, Vol. 34, p. 424-426Article in journal (Refereed)
  • 25.
    Bonnedahl, Jonas
    et al.
    Uppsala University ; Kalmar County Hospital.
    Drobni, M
    Gauthier-Clerc, M
    Hernandez, Jorge
    Kalmar County Hospital.
    Granholm, S
    Kayser, Y
    Melhus, Å
    Kahlmeter, G
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Johansson, A
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Dissemination of Escherichia coli with CTX-M Type ESBL between Humans and Yellow-Legged Gulls in the South of France2009In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 4, no Article number: e5958Article in journal (Refereed)
    Abstract [en]

     Extended Spectrum beta-Lactamase (ESBL) producing Enterobacteriaceae started to appear in the 1980s, and have since emerged as some of the most significant hospital-acquired infections with Escherichia coli and Klebsiella being main players. More than 100 different ESBL types have been described, the most widespread being the CTX-M beta-lactamase enzymes (bla(CTX-M) genes). This study focuses on the zoonotic dissemination of ESBL bacteria, mainly CTX-M type, in the southern coastal region of France. We found that the level of general antibiotic resistance in single randomly selected E. coli isolates from wild Yellow-legged Gulls in France was high. Nearly half the isolates (47,1%) carried resistance to one or more antibiotics (in a panel of six antibiotics), and resistance to tetracycline, ampicillin and streptomycin was most widespread. In an ESBL selective screen, 9,4% of the gulls carried ESBL producing bacteria and notably, 6% of the gulls carried bacteria harboring CTX-M-1 group of ESBL enzymes, a recently introduced and yet the most common clinical CTX-M group in France. Multi locus sequence type and phylogenetic group designations were established for the ESBL isolates, revealing that birds and humans share E. coli populations. Several ESBL producing E. coli isolated from birds were identical to or clustered with isolates with human origin. Hence, wild birds pick up E. coli of human origin, and with human resistance traits, and may accordingly also act as an environmental reservoir and melting pot of bacterial resistance with a potential to re-infect human populations.

  • 26.
    Bonnedahl, Jonas
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Kalmar County Hospital.
    Hernandez, Jorge
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Uppsala University ; Kalmar County Hospital.
    Stedt, Johan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Bjorn
    Uppsala University.
    Drobni, Mirva
    Uppsala University.
    Extended-Spectrum beta-Lactamases in Escherichia coli and Klebsiella pneumoniae in Gulls, Alaska, USA2014In: Emerging Infectious Diseases, ISSN 1080-6040, E-ISSN 1080-6059, Vol. 20, no 5, p. 897-899Article in journal (Refereed)
  • 27. Bonnedahl, Jonas
    et al.
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Broman, Tina
    Jalava, J
    Huovinen, P
    Österblad, Monika
    Antibiotic susceptibility of faecal bacteria in Antarctic penguins2008In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 31, p. 759-763Article in journal (Refereed)
  • 28.
    Bonnedahl, Jonas
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Kalmar County Hospital.
    Stedt, Johan
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Svensson, Lovisa
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Drobni, Mirva
    Uppsala University.
    Olsen, Björn
    Uppsala University.
    Comparison of Extended-Spectrum beta-Lactamase (ESBL) CTX-M Genotypes in Franklin Gulls from Canada and Chile2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 10, article id e0141315Article in journal (Refereed)
    Abstract [en]

    Migratory birds have been suggested to contribute to long-distance dispersal of antimicrobial resistant bacteria, but tests of this hypothesis are lacking. In this study we determined resistance profiles and genotypes of ESBL-producing bacteria in randomly selected Escherichia coli from Franklin's gulls (Leucophaeus pipixcan) at breeding sites in Canada and compared with similar data from the gulls' wintering grounds in Chile. Resistant E. coli phenotypes were common, most notably to ampicillin (30.1%) and cefadroxil (15.1%). Furthermore, 17.0% of the gulls in Canada carried ESBL producing bacteria, which is higher than reported from human datasets from the same country. However, compared to gulls sampled in Chile (30.1%) the prevalence of ESBL was much lower. The dominant ESBL variants in Canada were bla(CTX-M-14) and bla(CTX-M-15) and differed in proportions to the data from Chile. We hypothesize that the observed differences in ESBL variants are more likely linked to recent exposure to bacteria from anthropogenic sources, suggesting high local dissemination of resistant bacteria both at breeding and non-breeding times rather than a significant trans-hemispheric exchange through migrating birds.

  • 29. Broman, Tina
    et al.
    Palmgren, Helena
    Bergström, Sven
    Sellin, Mats
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Danielsson-Tham, Marie-Louise
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Campylobacter jejuni in Black-Headed Gulls (Larus ridibundus): prevalence, genotypes, and influence on C. jejuni epidemiology2002In: Journal of Clinical Microbiology, Vol. 40, p. 4594-4602Article in journal (Refereed)
  • 30. Broman, Tina
    et al.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Dahlgren, Daniel
    Carlsson, Inger
    Eliasson, Ingvar
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Diversities and Similarities in PFGE profiles of Campylobacter jejuni isolated from Migrating Birds and Humans2004In: Journal of Applied Microbiology, Vol. 96, p. 834-843Article in journal (Refereed)
  • 31.
    Chapman, Joanne R.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Helin, Anu S.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Wille, Michelle
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Uppsala University.
    Atterby, Clara
    Uppsala University.
    Jarhult, Josef D.
    Uppsala University.
    Fridlund, Jimmy
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    A Panel of Stably Expressed Reference Genes for Real-Time qPCR Gene Expression Studies of Mallards (Anas platyrhynchos)2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 2, article id e0149454Article in journal (Refereed)
    Abstract [en]

    Determining which reference genes have the highest stability, and are therefore appropriate for normalising data, is a crucial step in the design of real-time quantitative PCR (qPCR) gene expression studies. This is particularly warranted in non-model and ecologically important species for which appropriate reference genes are lacking, such as the mallard-a key reservoir of many diseases with relevance for human and livestock health. Previous studies assessing gene expression changes as a consequence of infection in mallards have nearly universally used beta-actin and/or GAPDH as reference genes without confirming their suitability as normalisers. The use of reference genes at random, without regard for stability of expression across treatment groups, can result in erroneous interpretation of data. Here, eleven putative reference genes for use in gene expression studies of the mallard were evaluated, across six different tissues, using a low pathogenic avian influenza A virus infection model. Tissue type influenced the selection of reference genes, whereby different genes were stable in blood, spleen, lung, gastrointestinal tract and colon. beta-actin and GAPDH generally displayed low stability and are therefore inappropriate reference genes in many cases. The use of different algorithms (GeNorm and NormFinder) affected stability rankings, but for both algorithms it was possible to find a combination of two stable reference genes with which to normalise qPCR data in mallards. These results highlight the importance of validating the choice of normalising reference genes before conducting gene expression studies in ducks. The fact that nearly all previous studies of the influence of pathogen infection on mallard gene expression have used a single, non-validated reference gene is problematic. The toolkit of putative reference genes provided here offers a solid foundation for future studies of gene expression in mallards and other waterfowl.

  • 32.
    Chapman, Joanne R.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hellgren, Olof
    Lund University.
    Helin, Anu S.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Kraus, Robert H. S.
    Univ Konstanz, Germany;Max Planck Inst Ornithology, Germany.
    Cromie, Ruth L.
    Wildfowl & Wetlands Trust, UK.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    The Evolution of Innate Immune Genes: Purifying and Balancing Selection on beta-Defensins in Waterfowl2016In: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 33, no 12, p. 3075-3087Article in journal (Refereed)
    Abstract [en]

    In disease dynamics, high immune gene diversity can confer a selective advantage to hosts in the face of a rapidly evolving and diverse pathogen fauna. This is supported empirically for genes involved in pathogen recognition and signalling. In contrast, effector genes involved in pathogen clearance may be more constrained. beta-Defensins are innate immune effector genes; their main mode of action is via disruption of microbial membranes. Here, five beta-defensin genes were characterized in mallards (Anas platyrhynchos) and other waterfowl; key reservoir species for many zoonotic diseases. All five genes showed remarkably low diversity at the individual-, population-, and species-level. Furthermore, there was widespread sharing of identical alleles across species divides. Thus, specific beta-defensin alleles were maintained not only spatially but also over long temporal scales, with many amino acid residues being fixed across all species investigated. Purifying selection to maintain individual, highly efficacious alleles was the primary evolutionary driver of these genes in waterfowl. However, we also found evidence for balancing selection acting on the most recently duplicated beta-defensin gene (AvBD3b). For this gene, we found that amino acid replacements were more likely to be radical changes, suggesting that duplication of beta-defensin genes allows exploration of wider functional space. Structural conservation to maintain function appears to be crucial for avian beta-defensin effector molecules, resulting in low tolerance for new allelic variants. This contrasts with other types of innate immune genes, such as receptor and signalling molecules, where balancing selection to maintain allelic diversity has been shown to be a strong evolutionary force.

  • 33.
    Chapman, Joanne R.
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    With Reference to Reference Genes: A Systematic Review of Endogenous Controls in Gene Expression Studies2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 11, article id e0141853Article, review/survey (Refereed)
    Abstract [en]

    The choice of reference genes that are stably expressed amongst treatment groups is a crucial step in real-time quantitative PCR gene expression studies. Recent guidelines have specified that a minimum of two validated reference genes should be used for normalisation. However, a quantitative review of the literature showed that the average number of reference genes used across all studies was 1.2. Thus, the vast majority of studies continue to use a single gene, with beta-actin (ACTB) and/or glyceraldehyde 3-phosphate dehydrogenase (GAPDH) being commonly selected in studies of vertebrate gene expression. Few studies (15%) tested a panel of potential reference genes for stability of expression before using them to normalise data. Amongst studies specifically testing reference gene stability, few found ACTB or GAPDH to be optimal, whereby these genes were significantly less likely to be chosen when larger panels of potential reference genes were screened. Fewer reference genes were tested for stability in non-model organisms, presumably owing to a dearth of available primers in less well characterised species. Furthermore, the experimental conditions under which real-time quantitative PCR analyses were conducted had a large influence on the choice of reference genes, whereby different studies of rat brain tissue showed different reference genes to be the most stable. These results highlight the importance of validating the choice of normalising reference genes before conducting gene expression studies.

  • 34. Christersson, Linus
    et al.
    Blomqvist, Maria
    Grannas, Karin
    Thollesson, Mikael
    Laroucau, Karine
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Eliasson, Ingvar
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Herrmann, Björn
    A novel Chlamydiaceae-like bacterium found in fecal specimens from sea birds from the Bering Sea.2010In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 2, no 4, p. 605-610Article in journal (Refereed)
    Abstract [en]

    The family Chlamydiaceae contains several bacterial pathogens of important human and veterinary medical concern, such as Chlamydia trachomatis and Chlamydophila psittaci. Within the order Chlamydiales there are also an increasing number of chlamydia-like bacteria whose biodiversity, host range and environmental spread seem to have been largely underestimated, and which are currently being investigated for their potential medical relevance. In this study we present 16S rRNA, rnpB and ompA gene sequence data congruently indicating a novel chlamydia-like bacterium found in faecal specimens from opportunistic fish-eating sea birds, belonging to the Laridae and Alcidae families, from the Bering Sea. This novel bacterium appears to be closer to the Chlamydiaceae than other chlamydia-like bacteria and is most likely a novel genus within the Chlamydiaceae family.

  • 35.
    Cody, Alison J.
    et al.
    Univ Oxford, UK.
    McCarthy, Noel D.
    Univ Oxford,UK;Hlth Protect Agcy, UK;Univ Warwick, UK;Univ Oxford, UK.
    Bray, James E.
    Univ Oxford, UK.
    Wimalarathna, Helen M. L.
    Univ Oxford, UK.
    Colles, Frances M.
    Univ Oxford, UK.
    van Rensburg, Melissa J. Jansen
    Univ Oxford, UK.
    Dingle, Kate E.
    Univ Oxford, UK.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Maiden, Martin C. J.
    Univ Oxford, UK.
    Wild bird-associated Campylobacter jejuni isolates are a consistent source of human disease, in Oxfordshire, United Kingdom2015In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 7, no 5, p. 782-788Article in journal (Refereed)
    Abstract [en]

    The contribution of wild birds as a source of human campylobacteriosis was investigated in Oxfordshire, United Kingdom (UK) over a 10 year period. The probable origin of human Campylobacter jejuni genotypes, as described by multilocus sequence typing, was estimated by comparison with reference populations of isolates from farm animals and five wild bird families, using the STRUCTURE algorithm. Wild bird-attributed isolates accounted for between 476 (2.1%) and 543 (3.5%) cases annually. This proportion did not vary significantly by study year (P=0.934) but varied seasonally, with wild bird-attributed genotypes comprising a greater proportion of isolates during warmer compared with cooler months (P=0.003). The highest proportion of wild bird-attributed illness occurred in August (P<0.001), with a significantly lower proportion in November (P=0.018). Among genotypes attributed to specific groups of wild birds, seasonality was most apparent for Turdidae-attributed isolates, which were absent during cooler, winter months. This study is consistent with some wild bird species representing a persistent source of campylobacteriosis, and contributing a distinctive seasonal pattern to disease burden. If Oxfordshire is representative of the UK as a whole in this respect, these data suggest that the national burden of wild bird-attributed isolates could be in the order of 10000 annually.

  • 36.
    Elfving, Karin
    et al.
    Uppsala University Hospital ; Falu Hospital.
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Uppsala University Hospital.
    Bergström, Sven
    Umeå University.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Uppsala University Hospital.
    Lundkvist, Åke
    Swedish Institute for Infectious Disease Control.
    Sjöstedt, Anders
    Umeå University Hospital.
    Mejlon, Hans
    Uppsala University.
    Nilsson, Kenneth
    Uppsala University Hospital ; Falu Hospital ; Uppsala University.
    Dissemination of Spotted Fever Rickettsia Agents in Europe by Migrating Birds2010In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, no 1, article id e8572Article in journal (Refereed)
    Abstract [en]

    Migratory birds are known to play a role as long-distance vectors for many microorganisms. To investigate whether this is true of rickettsial agents as well, we characterized tick infestation and gathered ticks from 13,260 migratory passerine birds in Sweden. A total of 1127 Ixodes spp. ticks were removed from these birds and the extracted DNA from 957 of them was available for analyses. The DNA was assayed for detection of Rickettsia spp. using real-time PCR, followed by DNA sequencing for species identification. Rickettsia spp. organisms were detected in 108 (11.3%) of the ticks. Rickettsia helvetica, a spotted fever rickettsia associated with human infections, was predominant among the PCR-positive samples. In 9 (0.8%) of the ticks, the partial sequences of 17kDa and ompB genes showed the greatest similarity to Rickettsia monacensis, an etiologic agent of Mediterranean spotted fever-like illness, previously described in southern Europe as well as to the Rickettsia sp. IrITA3 strain. For 15 (1.4%) of the ticks, the 17kDa, ompB, gltA and ompA genes showed the greatest similarity to Rickettsia sp. strain Davousti, Rickettsia japonica and Rickettsia heilongjiangensis, all closely phylogenetically related, the former previously found in Amblyomma tholloni ticks in Africa and previously not detected in Ixodes spp. ticks. The infestation prevalence of ticks infected with rickettsial organisms was four times higher among ground foraging birds than among other bird species, but the two groups were equally competent in transmitting Rickettsia species. The birds did not seem to serve as reservoir hosts for Rickettsia spp., but in one case it seems likely that the bird was rickettsiemic and that the ticks had acquired the bacteria from the blood of the bird. In conclusion, migratory passerine birds host epidemiologically important vector ticks and Rickettsia species and contribute to the geographic distribution of spotted fever rickettsial agents and their diseases.

  • 37.
    Ellström, Patrik
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Jourdain, Elsa
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Gunnarsson, Oskar
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The ”human influenza receptor” Neu5Ac alpha 2,6Gal is expressed among different taxa of wild birds2009In: Archives of Virology, ISSN 0304-8608, E-ISSN 1432-8798, Vol. 154, no 9, p. 1533-1537Article in journal (Refereed)
  • 38.
    Ellström, Patrik
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Latorre-Margalef, Neus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Griekspoor, Petra
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Olofsson, Jenny
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Wahlgren, John
    Ctr Microbiol Preparedness KCB, Swedish Inst Infect Dis Control SMI, SE-17182 Solna, Sweden.
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Sampling for low-pathogenic avian influenza A virus in wild Mallard ducks: Oropharyngeal versus cloacal swabbing2008In: Vaccine, ISSN 0264-410X, E-ISSN 1873-2518, Vol. 26, no 35, p. 4414-4416Article in journal (Refereed)
  • 39.
    Elmberg, Johan
    et al.
    Kristianstad University.
    Berg, Charlotte
    Swedish University of Agricultural Sciences.
    Lerner, Henrik
    Ersta Sköndal Bräcke University College.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hessel, Rebecca
    Kristianstad University.
    Potential disease transmission from wild geese and swans to livestock, poultry and humans: a review of the scientific literature from a One Health perspective2017In: Infection Ecology & Epidemiology, ISSN 2000-8686, E-ISSN 2000-8686, Vol. 7, no 1, p. 1-21, article id 1300450Article in journal (Refereed)
    Abstract [en]

    There are more herbivorous waterfowl (swans and geese) close to humans, livestock and poultry than ever before. This creates widespread conflict with agriculture and other human interests, but also debate about the role of swans and geese as potential vectors of disease of relevance for human and animal health. Using a One Health perspective, we provide the first comprehensive review of the scientific literature about the most relevant viral, bacterial, and unicellular pathogens occurring in wild geese and swans. Research thus far suggests that these birds may play a role in transmission of avian influenza virus, Salmonella, Campylobacter, and antibiotic resistance. On the other hand, at present there is no evidence that geese and swans play a role in transmission of Newcastle disease, duck plague, West Nile virus, Vibrio, Yersinia, Clostridium, Chlamydophila, and Borrelia. Finally, based on present knowledge it is not possible to say if geese and swans play a role in transmission of Escherichia coli, Pasteurella, Helicobacter, Brachyspira, Cryptosporidium, Giardia, and Microsporidia. This is largely due to changes in classification and taxonomy, rapid development of identification methods and lack of knowledge about host specificity. Previous research tends to overrate the role of geese and swans as disease vectors; we do not find any evidence that they are significant transmitters to humans or livestock of any of the pathogens considered in this review. Nevertheless, it is wise to keep poultry and livestock separated from small volume waters used by many wild waterfowl, but there is no need to discourage livestock grazing in nature reserves or pastures where geese and swans are present. Under some circumstances it is warranted to discourage swans and geese from using wastewater ponds, drinking water reservoirs, and public beaches. Intensified screening of swans and geese for AIV, West Nile virus and anatid herpesvirus is warranted.

  • 40.
    Eriksson, Per
    et al.
    Uppsala University.
    Lindskog, Cecilia
    Uppsala University.
    Engholm, Ebbe
    Univ Copenhagen, Denmark.
    Blixt, Ola
    Univ Copenhagen, Denmark.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Munster, Vincent
    NIAID, USA.
    Lundkvist, Åke
    Uppsala University.
    Olsen, Björn
    Uppsala University.
    Jourdain, Elsa
    INRA, France.
    Ellström, Patrik
    Uppsala University.
    Characterization of avian influenza virus attachment patterns to human and pig tissues2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 12215Article in journal (Refereed)
    Abstract [en]

    Wild birds of Anseriformes and Charadriiformes are natural reservoirs of influenza A viruses (IAVs). Occasionally, IAVs transmit and adapt to mammalian hosts, and are maintained as epidemic strains in their new hosts. Viral adaptions to mammalian hosts include altered receptor preference of host epithelial sialylated oligosaccharides from terminal alpha 2,3-linked sialic acid (SA) towards alpha 2,6-linked SA. However, alpha 2,3-linked SA has been found in human respiratory tract epithelium, and human infections by avian IAVs (AIVs) have been reported. To further explore the attachment properties of AIVs, four AIVs of different subtypes were investigated on human and pig tissues using virus histochemistry. Additionally, glycan array analysis was performed for further characterization of IAVs' receptor structure tropism. Generally, AIV attachment was more abundant to human tissues than to pig tissues. The attachment pattern was very strong to human conjunctiva and upper respiratory tract, but variable to the lower respiratory tract. AIVs mainly attached to alpha 2,3-linked SA, but also to combinations of alpha 2,3-and alpha 2,6-linked SA. The low attachment of these AIV isolates to pig tissues, but high attachment to human tissues, addresses the question whether AIVs in general require passage through pigs to obtain adaptions towards mammalian receptor structures.

  • 41.
    Eriksson, Per
    et al.
    Uppsala University, Sweden.
    Lindskog, Cecilia
    Uppsala University, Sweden.
    Lorente-Leal, Victor
    Uppsala University, Sweden.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Gonzalez-Acuna, Daniel
    Univ Concepcion, Chile.
    Jarhult, Josef D.
    Uppsala University, Sweden.
    Lundkvist, Åke
    Uppsala University, Sweden.
    Olsen, Björn
    Uppsala University, Sweden.
    Jourdain, Elsa
    INRA, France.
    Ellström, Patrik
    Uppsala University, Sweden.
    Attachment Patterns of Human and Avian Influenza Viruses to Trachea and Colon of 26 Bird Species - Support for the Community Concept2019In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 10, article id 815Article in journal (Refereed)
    Abstract [en]

    Avian influenza A viruses (AIVs) have a broad host range, but are most intimately associated with waterfowl (Anseriformes) and, in the case of the H13 and H16 subtypes, gulls (Charadriiformes). Host associations are multifactorial, but a key factor is the ability of the virus to bind host cell receptors and thereby initiate infection. The current study aims at investigating the tissue attachment pattern of a panel of AIVs, comprising H3N2, H6N1, H12N5, and H16N3, to avian trachea and colon tissue samples obtained from host species of different orders. Virus attachment was not restricted to the bird species or order from which the virus was isolated. Instead, extensive virus attachment was observed to several distantly related avian species. In general, more virus attachment and receptor expression were observed in trachea than in colon samples. Additionally, a human seasonal H3N2 virus was studied. Unlike the studied AIVs, this virus mainly attached to tracheae from Charadriiformes and a very limited set of avian cola. In conclusion, the reported results highlight the importance of AIV attachment to trachea in many avian species. Finally, the importance of chickens and mallards in AIVs dynamics was illustrated by the abundant AIV attachment observed.

  • 42. Frick, Jerker
    et al.
    Lindberg, Richard
    Tysklind, Mats
    Haemig, Paul
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Waldenström, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Wallensten, Anders
    Olsen, Björn
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Anitiviral Oseltamivir is not removed or degraded in normal sewage ater treatment: implications for the develoment of resitance by influenza A virus2007In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 2, no 10Article in journal (Refereed)
  • 43.
    Fuller, Trevon
    et al.
    University of California, USA.
    Bensch, Staffan
    Lund University.
    Müller, Inge
    Max Planck Institute for Ornithology, Germany.
    Novembre, John
    University of California, USA.
    Pérez-Tris, Javier
    Universidad Complutense de Madrid, Spain.
    Ricklefs, Robert E
    University of Missouri-St. Louis, USA.
    Smith, Thomas B
    University of California, USA.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The ecology of emerging infectious diseases in migratory birds: an assessment of the role of climate change and priorities for future research.2012In: EcoHealth, ISSN 1612-9202, E-ISSN 1612-9210, Vol. 9, no 1, p. 80-88Article in journal (Refereed)
    Abstract [en]

    Pathogens that are maintained by wild birds occasionally jump to human hosts, causing considerable loss of life and disruption to global commerce. Preliminary evidence suggests that climate change and human movements and commerce may have played a role in recent range expansions of avian pathogens. Since the magnitude of climate change in the coming decades is predicted to exceed climatic changes in the recent past, there is an urgent need to determine the extent to which climate change may drive the spread of disease by avian migrants. In this review, we recommend actions intended to mitigate the impact of emergent pathogens of migratory birds on biodiversity and public health. Increased surveillance that builds upon existing bird banding networks is required to conclusively establish a link between climate and avian pathogens and to prevent pathogens with migratory bird reservoirs from spilling over to humans.

  • 44.
    Gillman, Anna
    et al.
    Uppsala University.
    Muradrasoli, Shaman
    Swedish University of Agricultural Sciences.
    Söderstrom, Hanna
    Umeå University.
    Nordh, Johan
    Uppsala University.
    Bröjer, Caroline
    Swedish University of Agricultural Sciences.
    Lindberg, Richard H.
    Umeå University.
    Latorre-Margalef, Neus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Björn
    Uppsala University.
    Järhult, Josef D.
    Uppsala University.
    Resistance Mutation R292K Is Induced in Influenza A(H6N2) Virus by Exposure of Infected Mallards to Low Levels of Oseltamivir2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 8, article id e71230Article in journal (Refereed)
    Abstract [en]

    Resistance to neuraminidase inhibitors (NAIs) is problematic as these drugs constitute the major treatment option for severe influenza. Extensive use of the NAI oseltamivir (Tamiflu(R)) results in up to 865 ng/L of its active metabolite oseltamivir carboxylate (OC) in river water. There one of the natural reservoirs of influenza A, dabbling ducks, can be exposed. We previously demonstrated that an influenza A(H1N1) virus in mallards (Anas platyrhynchos) exposed to 1 mu g/L of OC developed oseltamivir resistance through the mutation H274Y (N2-numbering). In this study, we assessed the resistance development in an A(H6N2) virus, which belongs to the phylogenetic N2 group of neuraminidases with distinct functional and resistance characteristics. Mallards were infected with A(H6N2) while exposed to 120 ng/L, 1.2 mu g/L or 12 mu g/L of OC in their sole water source. After 4 days with 12 mu g/L of OC exposure, the resistance mutation R292K emerged and then persisted. Drug sensitivity was decreased approximate to 13,000-fold for OC and approximate to 7.8-fold for zanamivir. Viral shedding was similar when comparing R292K and wild-type virus indicating sustained replication and transmission. Reduced neuraminidase activity and decrease in recovered virus after propagation in embryonated hen eggs was observed in R292K viruses. The initial, but not the later R292K isolates reverted to wild-type during egg-propagation, suggesting a stabilization of the mutation, possibly through additional mutations in the neuraminidase (D113N or D141N) or hemagglutinin (E216K). Our results indicate a risk for OC resistance development also in a N2 group influenza virus and that exposure to one NAI can result in a decreased sensitivity to other NAIs as well. If established in influenza viruses circulating among wild birds, the resistance could spread to humans via re-assortment or direct transmission. This could potentially cause an oseltamivir-resistant pandemic; a serious health concern as preparedness plans rely heavily on oseltamivir before vaccines can be mass-produced.

  • 45.
    Gillman, Anna
    et al.
    Uppsala University.
    Muradrasoli, Shaman
    Uppsala University;Swedish University of Agricultural Sciences.
    Söderström, Hanna
    Umeå University.
    Holmberg, Fredrik
    Uppsala University.
    Latorre-Margalef, Neus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Tolf, Conny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Gunnarsson, Gunnar
    Kristianstad University.
    Olsen, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Uppsala University.
    Jarhult, Josef D.
    Uppsala University.
    Oseltamivir-Resistant Influenza A (H1N1) Virus Strain with an H274Y Mutation in Neuraminidase Persists without Drug Pressure in Infected Mallards2015In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 81, no 7, p. 2378-2383Article in journal (Refereed)
    Abstract [en]

    Influenza A virus (IAV) has its natural reservoir in wild waterfowl, and emerging human IAVs often contain gene segments from avian viruses. The active drug metabolite of oseltamivir (oseltamivir carboxylate [OC]), stockpiled as Tamiflu for influenza pandemic preparedness, is not removed by conventional sewage treatment and has been detected in river water. There, it may exert evolutionary pressure on avian IAV in waterfowl, resulting in the development of resistant viral variants. A resistant avian IAV can circulate among wild birds only if resistance does not restrict viral fitness and if the resistant virus can persist without continuous drug pressure. In this in vivo mallard (Anas platyrhynchos) study, we tested whether an OC-resistant avian IAV (H1N1) strain with an H274Y mutation in the neuraminidase (NA-H274Y) could retain resistance while drug pressure was gradually removed. Successively infected mallards were exposed to decreasing levels of OC, and fecal samples were analyzed for the neuraminidase sequence and phenotypic resistance. No reversion to wild-type virus was observed during the experiment, which included 17 days of viral transmission among 10 ducks exposed to OC concentrations below resistance induction levels. We conclude that resistance in avian IAV that is induced by exposure of the natural host to OC can persist in the absence of the drug. Thus, there is a risk that human-pathogenic IAVs that evolve from IAVs circulating among wild birds may contain resistance mutations. An oseltamivir-resistant pandemic IAV would pose a substantial public health threat. Therefore, our observations underscore the need for prudent oseltamivir use, upgraded sewage treatment, and surveillance for resistant IAVs in wild birds.

  • 46.
    Gillman, Anna
    et al.
    Uppsala University.
    Nykvist, Marie
    Uppsala University.
    Muradrasoli, Shaman
    Uppsala University;Swedish University of Agricultural Sciences.
    Söderström, Hanna
    Umeå University.
    Wille, Michelle
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Daggfeldt, Annika
    National Veterinary Institute.
    Brojer, Caroline
    National Veterinary Institute.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Björn
    Uppsala University.
    Jarhult, Josef D.
    Uppsala University.
    Influenza A(H7N9) Virus Acquires Resistance-Related Neuraminidase I222T Substitution When Infected Mallards Are Exposed to Low Levels of Oseltamivir in Water2015In: Antimicrobial Agents and Chemotherapy, ISSN 0066-4804, E-ISSN 1098-6596, Vol. 59, no 9, p. 5196-5202Article in journal (Refereed)
    Abstract [en]

    Influenza A virus (IAV) has its natural reservoir in wild waterfowl, and new human IAVs often contain gene segments originating from avian IAVs. Treatment options for severe human influenza are principally restricted to neuraminidase inhibitors (NAIs), among which oseltamivir is stockpiled in preparedness for influenza pandemics. There is evolutionary pressure in the environment for resistance development to oseltamivir in avian IAVs, as the active metabolite oseltamivir carboxylate (OC) passes largely undegraded through sewage treatment to river water where waterfowl reside. In an in vivo mallard (Anas platyrhynchos) model, we tested if low-pathogenic avian influenza A(H7N9) virus might become resistant if the host was exposed to low levels of OC. Ducks were experimentally infected, and OC was added to their water, after which infection and transmission were maintained by successive introductions of uninfected birds. Daily fecal samples were tested for IAV excretion, genotype, and phenotype. Following mallard exposure to 2.5 mu g/liter OC, the resistance-related neuraminidase (NA) I222T substitution, was detected within 2 days during the first passage and was found in all viruses sequenced from subsequently introduced ducks. The substitution generated 8-fold and 2.4-fold increases in the 50% inhibitory concentration (IC50) for OC (P < 0.001) and zanamivir (P = 0.016), respectively. We conclude that OC exposure of IAV hosts, in the same concentration magnitude as found in the environment, may result in amino acid substitutions, leading to changed antiviral sensitivity in an IAV subtype that can be highly pathogenic to humans. Prudent use of oseltamivir and resistance surveillance of IAVs in wild birds are warranted.

  • 47.
    Griekspoor, Petra
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Colles, Frances M.
    Mccarthy, Noel D.
    Hansbro, Philip M.
    Ashhurst-Smith, Chris
    Olsen, Björn
    Department of Medical Sciences, Uppsala University.
    Hasselquist, Dennis
    Maiden, Martin C. J.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Marked host specificity and lack of phylogeographic population structure of Campylobacter jejuni in wild birds2013In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 22, no 5, p. 1463-1472Article in journal (Refereed)
    Abstract [en]

    Zoonotic pathogens often infect several animal species, and gene flow among populations infecting different host species may affect the biological traits of the pathogen including host specificity, transmissibility and virulence. The bacterium Campylobacter jejuni is a widespread zoonotic multihost pathogen, which frequently causes gastroenteritis in humans. Poultry products are important transmission vehicles to humans, but the bacterium is common in other domestic and wild animals, particularly birds, which are a potential infection source. Population genetic studies of C. jejuni have mainly investigated isolates from humans and domestic animals, so to assess C. jejuni population structure more broadly and investigate host adaptation, 928 wild bird isolates from Europe and Australia were genotyped by multilocus sequencing and compared to the genotypes recovered from 1366 domestic animal and human isolates. Campylobacter jejuni populations from different wild bird species were distinct from each other and from those from domestic animals and humans, and the host species of wild bird was the major determinant of C. jejuni genotype, while geographic origin was of little importance. By comparison, C. jejuni differentiation was restricted between more phylogenetically diverse farm animals, indicating that domesticated animals may represent a novel niche for C. jejuni and thereby driving the evolution of those bacteria as they exploit this niche. Human disease is dominated by isolates from this novel domesticated animal niche.

  • 48.
    Griekspoor, Petra
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Engvall, Eva
    Olsen, Björn
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Multilocus sequence typing of Campylobacter jejuni from broilers2010In: Veterinary Microbiology, ISSN 0378-1135, E-ISSN 1873-2542, Vol. 140, p. 180-185Article in journal (Refereed)
    Abstract [en]

    Campylobacter jejuni isolates from a national Swedish Campylobacter monitoring in broilers were characterized by multilocus sequencing typing (MLST) in order to study the genetic diversity of this bacterial population. Isolates were initially characterized by pulsed-field gel electrophoresis (PFGE). One hundred were chosen for MLST genotyping. PFGE identified 69 distinct types compared to 44 different sequence types (STs) identified with MLST. Eighteen STs had not been described previously, while the remaining 26 STs were assigned to previously known clonal complexes. The majority of isolates were of genotypes noted in broilers and in humans in earlier studies. However, three clonal complexes, ST-206 complex, ST-677 complex and ST-1034 complex, previously associated with wild bird and environmental samples, were among the genotypes found. This study shows that most of the Swedish broiler isolates were of genotypes noted as common in broilers. However, it also highlights the potential influence of environmental sources on the broiler C jejuni genotypes.

  • 49.
    Griekspoor, Petra
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Hansbro, Philip M.
    University of Newcastle, Australia.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Uppsala University.
    Olsen, Björn
    Uppsala University.
    Campylobacter jejuni sequence types show remarkable spatial and temporal stability in Blackbirds2015In: Infection Ecology & Epidemiology, ISSN 2000-8686, E-ISSN 2000-8686, Vol. 5, article id 28383Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The zoonotic bacterium Campylobacter jejuni has a broad host range but is especially associated with birds, both domestic and wild. Earlier studies have indicated thrushes of the genus Turdus in Europe to be frequently colonized with C. jejuni, and predominately with host-associated specific genotypes. The European Blackbird Turdus merula has a large distribution in Europe, including some oceanic islands, and was also introduced to Australia by European immigrants in the 1850s.

    METHODS: The host specificity and temporal stability of European Blackbird C. jejuni was investigated with multilocus sequence typing in a set of isolates collected from Sweden, Australia, and The Azores.

    RESULTS: Remarkably, we found that the Swedish, Australian, and Azorean isolates were genetically highly similar, despite extensive spatial and temporal isolation. This indicates adaptation, exquisite specificity, and stability in time for European Blackbirds, which is in sharp contrast with the high levels of recombination and mutation found in poultry-related C. jejuni genotypes.

    CONCLUSION: The maintenance of host-specific signals in spatially and temporally separated C. jejuni populations suggests the existence of strong purifying selection for this bacterium in European Blackbirds.

  • 50.
    Griekspoor, Petra
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olofsson, Jenny
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Axelsson Olsson, Diana
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Olsen, Björn
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Multilocus Sequence Typing and FlaA Sequencing Reveal the Genetic Stability of Campylobacter jejuni Enrichment during Coculture with Acanthamoeba polyphaga2013In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 79, no 7, p. 2477-2479Article in journal (Refereed)
    Abstract [en]

    Low concentrations of Campylobacter jejuni cells in environmental samples make them difficult to study with conventional culture methods. Here, we show that enrichment by amoeba cocultures works well with low-concentration samples and that this method can be combined with molecular techniques without loss of genetic specificity.

1234 1 - 50 of 156
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf