Diagnosis of Trypanosoma cruzi infection in opossums, naturally infected, using indirect immunofluorescence reaction

One hundred and sixteen opossums captured in Bambuí, MG State, had an indirect fluorescent antibody test (IFAT) to detect circulating Trypanosoma cruzi antibodies. Forty-four of them (37.9%) reacted to T. cruzi, showing, titres ranging from 1:10 to 1:320. The parasite was demonstrated by parasitological examinations in 43 (97.7%) of these opossums. The IFAT presented co-positivity (97.7%) co-negativity (98.6%) and agreement (98.3%) rates when compared to xenodiagnosis and hemoculture. Considering the dilution 1:20 to discriminate reactions from the nonreactive ones, the IFAT is indicated as a diagnostic method, opossums. The IFAT on dry filter paper presented low rates of co-positivity (78.2%), agreement (76.0%) and consistent disagreement related to the non-reactive results.