Frequência de anticorpos anti-Toxoplasma gondii em suínos abatidos sem inspeção em Belém / Serologic diagnosis of Toxoplasma gondii in swines slaughtered without inspection in Northern Brazil

To survey the occurrence of IgM and IgG anti-T. gondii antibodies in pigs slaughtered without inspection, 110 serum samples from different localities were submitted to indirect hemaglutination test. A frequency of 50.0% (confidence interval 40.7% /.../ 59.3%, 95% significance) of positive sera was detected, with a distribution of frequency of 1.83% and 1.83%, 6.36% and 15.45%, 20.0% and 25.4%, 17.3% and 7.3%, and 4.5% and 0.0% for IgM and IgG antibodies, respectively in 1:16, 1:64, 1:256, 1:1024, and 1:2048 serum dilutions. The toxoplasmic infection was present among pigs in the city of Belém.