Perinatal infection with Trypanosoma vivax in a calf in Venezuela.

A case of perinatal infection by Trypanosoma vivax is reported in a 5-hr-old Carora local dairy breed calf. The levels of parasitemia were followed during 15 mo in the infected animal. Similarly, its immune response was monitored during 4 mo by the indirect fluorescent assay. Trypanosoma vivax was observed in Giemsa-stained blood films collected during the first 4 mo of life from the infected calf. Positivity was detected on days 0, 35, 80, and 125 after first sampling. Antibodies against T. vivax were detected each time the indirect fluorescent assay was performed, showing low titers (1:80-1:160). The importance of a congenital route of transmission for this Trypanosoma species in cattle herds, on a continent where Glossina spp. flies are absent, is discussed.