BACKGROUND: Serum samples from 630 milk sheep, in 33 dairy flocks representative of the southern area of the
Tuscany region, were tested for the presence of antibodies to Toxoplasma gondii using an indirect
immunofluorescence antibody test (IFAT). Questionnaires exploring the management system were completed by
the veterinarian in charge of the flocks.
RESULTS: At least one seropositive animal was found in 32 of the 33 flocks tested (97.0%; 95% CI: 84.2%, 99.9%). In
the positive flocks, median seroprevalence was 29.4% (interquartile range: 15.9%-46.1%). Overall animal-level
seroprevalence, adjusted for sampling weights and test sensitivity and specificity, was 33.3% (95% CI: 24.8%, 42.7%).
In a multivariable negative binomial regression model the number of seropositive animals in a flock decreased with
increasing flock size (for >400 vs. <300 animals: count ratio (CR) = 0.62; 95% CI: 0.41, 0.95; P = 0.028) and was greater
on farms where stray cats had access to animals’ water (CR = 1.54; 95% CI: 1.05, 2.26; P = 0.027).
CONCLUSIONS: Small flock size and access of cats to water are potential risk factors for Toxoplasma infection in sheep
in the Grosseto district in Tuscany, Italy. Sheep could be an important source of T. gondii infection in humans, since
we estimate that between 25% and 43% of sheep in the district were seropositive. Toxoplasmosis is also likely to be
an important cause of abortion in sheep in the district. Control and prophylactic measures must be adopted to
improve the rearing system and the implementation of health promoting programmes in a joint effort between
sheep farmers, farmers’ associations and veterinarians to inform about the means of transmission of the infection
and for a better understanding of the disease.
Additional file 1: Audit form on rearing practices from 33 farms in
Grosseto district, Tuscany, Italy.
The study idea was conceived by BCG. BCG, PS and AC participated in the
design of the study. FV and IM participated in the acquisition of the
laboratory data. AC collected serum samples with the attending veterinarians
and helped administering the questionnaire. PT and VC provided previously
acquired reference data. BCG and PT carried out the statistical analysis. Data
interpretation was done by all authors. BCG and PT drafted the manuscript.
All authors contributed to the critical revision of the manuscript for
important intellectual content and have seen and approved the final draft.