Toxoplasma seroprevalence in a rural population in France: detection of a household effect

<p>Abstract</p> <p>Background</p> <p><it>Toxoplasma gondii</it>, the agent of toxoplasmosis, has a complex life cycle. In humans, the parasite may be acquired either through ingestion of contaminated meat or through oocysts present in the environment. The importance of each source of contamination varies locally according to the environment characteristics and to differences concerning human eating habits and the presence of cats; thus, the risk factors may be determined through fine-scale studies. Here, we searched for factors associated with seropositivity in the population of two adjacent villages in Lorraine region, France.</p> <p>Methods</p> <p>All voluntary inhabitants filled out a questionnaire and gave a blood sample. The seroprevalence was estimated globally and according to the inhabitants' ages using a cubic spline regression. A mixed logistic regression model was used to quantify the effect of individual and household factors on the probability of seropositivity.</p> <p>Results</p> <p>Based on serological results from 273 persons, we estimated seroprevalence to be 47% (95% confidence interval: 41 to 53%). That seroprevalence increased with age: the slope was the steepest up to the age of 40 years (OR = 2.48 per 10-year increment, 95% credibility interval: [1.29 to 5.09]), but that increase was not significant afterwards. The probability of seropositivity tended to be higher in men than in women (OR = 2.01, 95% credibility interval: [0.92 to 4.72]) and in subjects eating raw vegetables at least once a week than in the others (OR = 8.4, 95% credibility interval: [0.93 to 72.1]). These effects were close to statistical significance. The multivariable analysis highlighted a significant seroprevalence heterogeneity among households. That seroprevalence varied between 6 and 91% (5^thand 95^thpercentile of the household seropositivity distribution).</p> <p>Conclusion</p> <p>The major finding is the household effect, with a strong heterogeneity of seroprevalence among households. This effect may be explained by common exposures of household members to local risk factors. Future work will quantify the link between the presence of oocysts in the soil and the seroprevalence of exposed households using a spatial analysis.</p

Local meteorological conditions, dynamics of seroconversion to Toxoplasma gondii in cats Felis catus and oocyst burden in a rural environment

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Toxoplasmosis in prey species and consequences for prevalence in feral cats: not all prey species are equal.

International audienceToxoplasma gondii is largely transmitted to definitive felid hosts through predation. Not all prey species represent identical risks of infection for cats because of differences in prey susceptibility, exposure and/or lifespan. Previously published studies have shown that prevalence in rodent and lagomorph species is positively correlated with body mass. We tested the hypothesis that different prey species have different infection risks by comparing infection dynamics of feral cats at 4 sites in the sub-Antarctic Kerguelen archipelago which differed in prey availability. Cats were trapped from 1994 to 2004 and anti-T. gondii IgG antibodies were detected using the modified agglutination test (> or =1:40). Overall seroprevalence was 51.09%. Antibody prevalence differed between sites, depending on diet and also on sex, after taking into account the effect of age. Males were more often infected than females and the difference between the sexes tended to be more pronounced in the site where more prey species were available. A difference in predation efficiency between male and female cats may explain this result. Overall, our results suggest that the composition of prey items in cat diet influences the risk of T. gondii infection. Prey compositon should therefore be considered important in any understanding of infection dynamics of T. gondii

Bovine tuberculosis in \textquotedblleftEurasian\textquotedblright badgers (Meles meles) in France

International audienceIn France, several surveillance programmeshave been carried out to monitor the presence of bovinetuberculosis (bTB) in badgers in regions where cattle orwildlife show high bTB prevalence (Seine-Maritime, Côted’Or, Dordogne/Charente). Diagnostic methods includepost-mortem examination, polymerase chain reaction(PCR) and/or microbiological culture. The frequency ofvisible lesions was significantly higher in Dordogne/Charente (14/283, 4.9 %) than in Côte d’Or (19/1146,1.7 %) and Seine-Maritime (2/160, 1.25 %) (Fisher’sexact test, p<0.001). Lesions were mainly located incephalic and thoracic lymph nodes with one badgershowing generalised tuberculosis. Near infected cattlefarms or pastures, Mycobacterium bovis was detectedusing the culture method in roughly 1 % (1/103) of thebadgers sampled in Seine-Maritime and in 5.6 % (49/878) of the badgers sampled in Côte d’Or. In Dordogne/Charente, the prevalence determined by PCR was 13.3 %(29/218). M. bovis was not found in badgers trapped inareas where there are no infected cattle. Spoligotypingand multiple locus variable number tandem repeat analysisshowed that all M. bovis strains isolated from badgerswere of the same genotype as those isolated from cattlein the vicinity, demonstrating an epidemiological linkbetween both species. These are the first cases of bTBin badgers reported in France. Further surveys and researchare needed to investigate the role badgers play i

Bouquetins du Bargy et infection brucellique : que nous révèle la génétique ?

National audiencePour comprendre les modalités d’infection d’une population naturelle par un agent pathogène et de transmission en son sein, il est nécessaire de connaître les caractéristiques génétiques et immunogénétiques de cette population. En effet, la diversité génétique est essentielle pour que les populations puissent s’adapter aux risques multi-parasitaires auxquels elles sont continuellement exposées. Or la diversité génétique d’une population est le reflet de son histoire démographique et évolutive. Lors de la réintroduction de bouquetins dans les Alpes, les populations ont subi plusieurs goulots d’étranglements successifs qui ont considérablement érodé leur variabilité génétique adaptative. Nous avons testé l’hypothèse que la sensibilité intrinsèque de la population de bouquetins (Capra ibex) du Bargy à la brucellose est liée à une forte consanguinité et une faible diversité génétique, notamment des gènes de l’immunité. Afin d’évaluer les risques de diffusion de l’agent pathogène, nous avons également mesuré les flux de gènes historiques et contemporains entre les différentes unités socio-spatiales du massif du Bargy et avec les populations des massifs alentours de Leschaux-Andey et des Aravis. Nos résultats suggèrent une très faible diversité génétique neutre et adaptative mais très comparable à celle observée dans un grand nombre de populations restaurées des Alpes et des populations sources. Par contre, sa taille efficace limitée (NE~50 individus) présage une forte diminution de la diversité génétique à moyen terme en l’absence de renforcement/migration. Dans l’ensemble, les gènes de l’immunité étudiés sont très peu polymorphes, mais certains variants rares dans la population (du gène SLC11A1 et dans une moindre mesure Tlr1) sont associés à une plus faible prévalence de brucellose, suggérant une résistance des animaux concernés. Enfin, les flux de gènes entre la population de Bargy et les populations voisines sont historiquement limités, mais nous avons détecté de nombreux mouvements contemporains entre Bargy et Aravis qui indiquent un risque de propagation de la maladie. Mot-clés : Brucella melitensis, diversité génétique, immunogénétique, SLC11A1

Male roe deer trade their immune system for secondary sexual character in the wild

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