| 1. |
- Ekstam, Börje, et al.
(författare)
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Predicting risk habitats for the transmission of the small liver fluke, Dicrocoelium dendriticum to grazing ruminants.
- 2011
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Ingår i: Geospatial Health. - Naples, Italy : Global Network for Geospatial Health. - 1827-1987 .- 1970-7096. ; 6:1, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- A multiple regression model was used to analyse if the structure of vegetation and soil patches in grazed units (pastures) can be used as explanatory variables to predict the prevalence of Dicrocoelium dendriticum, a common parasite of cattle and sheep, in grazing cattle stocks on the Baltic island of Öland in southern Sweden.The scale dependency was evaluated by comparing three levels of spatial resolution of patches. Prevalence data were obtained from slaughtered animals.Our models predict that the prevalence of D. dendriticum increases in grazed areas with woody vegetation, whereas moist and wet areas decrease parasite prevalence. The predictive power of the statistical models increased with increasing level of patch resolution. Approximately 42% of the variation in parasite prevalence (angular transformation) was explained by the areal proportion of vegetation types (4th-root-transformed).Based on the results obtained, we believe that our model strategy provides a rational and systematic tool to identify habitats that carry risk for D. dendriticum infection of ruminants, and that it can be applied to other parasites with similar life cycles such as Fasciola hepatica.
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| 2. |
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| 3. |
- Svanborg, Catharina, et al.
(författare)
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Adhesion, signal transduction and mucosal inflammation
- 2002
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Ingår i: Bacterial Adhesion to Host Tissues. - Cambridge : Cambridge University Press. - 9780521801072 - 0521801079 ; , s. 223-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Adel, Amany, et al.
(författare)
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Genetic Variations among Different Variants of G1-like Avian Influenza H9N2 Viruses and Their Pathogenicity in Chickens
- 2022
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Ingår i: Viruses. - : MDPI AG. - 1999-4915. ; 14:5
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Tidskriftsartikel (refereegranskat)abstract
- Since it was first discovered, the low pathogenic avian influenza (LPAI) H9N2 subtype has established linages infecting the poultry population globally and has become one of the most prevalent influenza subtypes in domestic poultry. Several different variants and genotypes of LPAI H9N2 viruses have been reported in Egypt, but little is known about their pathogenicity and how they have evolved. In this study, four different Egyptian LPAI H9N2 viruses were genetically and antigenically characterized and compared to representative H9N2 viruses from G1 lineage. Furthermore, the pathogenicity of three genetically distinct Egyptian LPAI H9N2 viruses was assessed by experimental infection in chickens. Whole-genome sequencing revealed that the H9N2 virus of the Egy-2 G1-B lineage (pigeon-like) has become the dominant circulating H9N2 genotype in Egypt since 2016. Considerable variation in virus shedding at day 7 post-infections was detected in infected chickens, but no significant difference in pathogenicity was found between the infected groups. The rapid spread and emergence of new genotypes of the influenza viruses pinpoint the importance of continuous surveillance for the detection of novel reassortant viruses, as well as monitoring the viral evolution.
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| 5. |
- Albinsson, Bo, et al.
(författare)
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Seroprevalence of tick-borne encephalitis virus and vaccination coverage of tick-borne encephalitis, Sweden, 2018 to 2019
- 2024
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Ingår i: Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin. - : European Centre for Disease Control and Prevention (ECDC). - 1560-7917 .- 1025-496X. ; 29:2
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn Sweden, information on seroprevalence of tick-borne encephalitis virus (TBEV) in the population, including vaccination coverage and infection, is scattered. This is largely due to the absence of a national tick-borne encephalitis (TBE) vaccination registry, scarcity of previous serological studies and use of serological methods not distinguishing between antibodies induced by vaccination and infection. Furthermore, the number of notified TBE cases in Sweden has continued to increase in recent years despite increased vaccination.AimThe aim was to estimate the TBEV seroprevalence in Sweden.MethodsIn 2018 and 2019, 2,700 serum samples from blood donors in nine Swedish regions were analysed using a serological method that can distinguish antibodies induced by vaccination from antibodies elicited by infection. The regions were chosen to reflect differences in notified TBE incidence.ResultsThe overall seroprevalence varied from 9.7% (95% confidence interval (CI): 6.6-13.6%) to 64.0% (95% CI: 58.3-69.4%) between regions. The proportion of vaccinated individuals ranged from 8.7% (95% CI: 5.8-12.6) to 57.0% (95% CI: 51.2-62.6) and of infected from 1.0% (95% CI: 0.2-3.0) to 7.0% (95% CI: 4.5-10.7). Thus, more than 160,000 and 1,600,000 individuals could have been infected by TBEV and vaccinated against TBE, respectively. The mean manifestation index was 3.1%.ConclusionA difference was observed between low- and high-incidence TBE regions, on the overall TBEV seroprevalence and when separated into vaccinated and infected individuals. The estimated incidence and manifestation index argue that a large proportion of TBEV infections are not diagnosed.
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| 6. |
- Atterby, Clara, et al.
(författare)
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The Potential of Isolation Source to Predict Colonization in Avian Hosts : A Case Study in Campylobacter jejuni Strains From Three Bird Species
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 7. |
- Axelsson Olsson, Diana, et al.
(författare)
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A simple method for long-term storage Acanthamoeba species
- 2009
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Ingår i: Parasitology Research. - : Springer Science and Business Media LLC. - 0932-0113 .- 1432-1955. ; 104:4, s. 935-937
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Axelsson Olsson, Diana, et al.
(författare)
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Acanthamoeba-Campylobacter coculture as a novel method for enrichment of Campylobacter species
- 2007
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 73:21, s. 6864-6869
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Axelsson Olsson, Diana, et al.
(författare)
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Amoebae and algae can prolong the survival of Campylobacter species in co-culture
- 2010
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Ingår i: Experimental parasitology. - : Elsevier BV. - 0014-4894 .- 1090-2449. ; 126:1, s. 59-64
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 10. |
- Axelsson Olsson, Diana, et al.
(författare)
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Campylobacter jejuni acid tolerance increases when co-incubated with amoebae
- 2009
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Konferensbidrag (refereegranskat)abstract
- 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.
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