Seroepidemiology of Toxoplasma gondii infection and parasite DNA in free-range chickens in Aguascalientes, Mexico.

The objectives of the study were to estimate the prevalence of anti-Toxoplasma gondii antibodies in free-range chickens in Aguascalientes, Mexico, its association with certain risk factors, and the frequency of parasite DNA in the heart. Eighty-one small rural family farms were included, and blood and heart samples were taken from 150 clinically healthy, adult, free-range chickens. Serum samples were processed by indirect immunofluorescence antibody test considering a dilution of 1:16 as a positive reaction, while the DNA detection was done by PCR. The correlation between the presence of antibodies and the potential risk factors was estimated with logistic regression. The overall seroprevalence in the examined populations was 67%, with a range from 33% to 100% among municipalities, and 78% of the farms having at least one seropositive bird. The PCR test identified the presence of parasite DNA for one case only. Among the variables, the presence of cats and the presence of other animal species on the farm were the ones that had the highest values, while the presence of feral cats and the presence of noxious fauna were also identified as potential risk factors. The results indicate high soil contamination by T. gondii oocysts, which implies the active role of cats living on the farms.