Landscape, herd management and within-herd seroprevalence of Toxoplasma gondii in beef cattle herds from Champagne-Ardenne, France

Toxoplasmosis is the most common parasitic zoonosis worldwide. Its prevalence and impact on human health are highly variable geographically. Humans may be infected by ingesting oocysts from the environment, or bradyzoits contained in meat products from various domestic species, thus data on the dynamics of toxoplasmosis in domestic herds is needed. However, few information is available on the factors that determine the level of infection of cattle herds. In this study, we aimed to estimate within-herd seroprevalence of toxoplasmosis in bovine herds and analyze its variability in relation with environmental characteristics and herd management. We tested the presence of anti Toxoplasma gondii antibodies in 1329 cattle from 24 beef herds in the Champagne-Ardenne region, using the Modified Agglutination Test. Information on herds was collected using a questionnaire. After describing the relationships between explanatory variables, we built a multivariate model using logistic Generalized Linear Models (GLMs) and estimated parameters with a Generalized Estimating Equations (GEE) procedure. The crude seroprevalence at threshold 1:24 equalled 7.8%, which is low, however positive individuals were found in 21 out of 24 herds. The final multivariate model showed that within-herd seroprevalence was highest in herds that were both small and isolated. The presence of cats modified the age-prevalence relationship: maximal seroprevalence was observed in oldest cows in farms without cats, and in youngest individuals in farms with cats. Finally, using a natural water point on pastures was associated to a high within-herd seroprevalence (Odds-Ratio: 1.93). Cows are often exposed to toxoplasmosis, however landscape characteristics (water point, isolation) and herd management (herd size, cats) may affect seroprevalence. Our results may help to find ways of reducing T. gondii prevalence in cattle.