Seroprevalence of Toxoplasma gondii infection in cattle, sheep, goats and pigs from the North of Portugal for human consumption.

Prevalence of antibodies to Toxoplasma gondii and risk factors associated with infection were assessed in food animals from the North of Portugal for human consumption. Antibodies were assayed by means of the modified agglutination test with a cut-off titre of 100 for cattle, and 20 for sheep, goats, and pigs; 7.5% of 161 cattle, 33.6% of 119 sheep, 18.5% of 184 goats, and 9.8% of 254 pigs were seropositive. Among the risk factors examined animal age was an important risk factor for seropositivity to T. gondii. The consumption of raw or undercooked meat should be regarded as an important source of infection to people in the study area.