BOVINE TRYPANOSOMIASIS CAUSED BY *TRYPANOSOMA VIVAX* IN A DAIRY HERD IN WESTERN PARANÁ: CASE REPORT

Abstract

Bovine trypanosomiasis caused by Trypanosoma vivax is a hemoparasitic disease of sanitary and economic importance in cattle production, particularly in dairy herds. This study reports an outbreak of bovine trypanosomiasis in a high-producing Holstein herd maintained under a confined production system in the municipality of São Pedro do Iguaçu, western Paraná, Brazil, in April 2026. Of the 26 animals evaluated, 17 presented clinical signs compatible with the disease, including fever, apathy, anorexia, dehydration, weight loss, pale mucous membranes, and a reduction in milk production from 32 to 12 liters per cow per day. Affected animals presented hematocrit values ranging from 13 to 16%, characterizing severe anemia. The diagnosis was confirmed by a rapid test specific for T. vivax and complemented by a qualitative qPCR positive for Trypanosoma spp. Two animals died and presented findings compatible with severe anemia and systemic compromise at necropsy. The epidemiological investigation indicated a possible association with the introduction of cattle from eastern Paraná without prior sanitary screening. Treatment included specific therapy against T. vivax, combined with antimicrobial therapy and supportive measures, including fluid therapy, supplementation, and blood transfusion in animals with severe anemia. The estimated economic loss was R$45,000.00. This case demonstrates the importance of early diagnosis, clinical monitoring, and the adoption of biosecurity measures for the prevention and control of trypanosomiasis in dairy herds.