Detecção de parasitas do gênero Trypanosoma em pequenos ruminantes no norte maranhense, Brasil

Abstract

Animal trypanosomiasis represents a significant sanitary and economic challenge for tropical livestock production, causing severe anemia and systemic inflammation in ruminants. In Brazil, Trypanosoma vivax is the most clinically relevant species in goats and sheep, associated with high morbidity, mortality, and production losses, though infections may also occur asymptomatically. While T. evansi and T. theileri can infect small ruminants, their pathogenicity in these hosts is considered low. In Maranhão state, the complete absence of studies on trypanosomiasis in small ruminants represents a critical epidemiological gap, leaving herds vulnerable to undiagnosed outbreaks. This study aimed to detect Trypanosoma spp. in small ruminants across Maranhão using direct and indirect diagnostic methods. Blood samples were collected from 84 goats and 210 sheep across 14 farms in São Bento, Pinheiro, and Itapecuru-Mirim municipalities during both dry and rainy seasons. A structured questionnaire documented risk factors, and individual animal records included demographic and health data. Diagnostic approaches included direct microscopy of blood smears, indirect ELISA for anti-T. vivax antibodies, species-specific PCR targeting T. vivax, T. evansi, and T. theileri genomic fragments, sequencing and phylogenetic analysis of PCR-positive samples (BLAST against GenBank), and statistical analysis using Chi-square and Fisher's exact tests for risk factors. No trypanosomes were detected by microscopy. Seroprevalence reached 14.28% (42/294), with 30 (10.20%) goats and 12 (4.08%) sheep testing positive. Two samples (0.68%) were PCR-positive for T. vivax, showing 100% identity with Brazilian isolates from buffaloes, cattle, small ruminants, and donkeys in GenBank. Phylogenetic analysis confirmed homology with these T. vivax strains. All samples tested negative for T. evansi and T. theileri. Significant risk factors (p<0.05) included host species (higher in goats), recent animal acquisitions, veterinary care availability, farm infrastructure quality, and housing type. This study provides the first molecular evidence of T. vivax infection in Maranhão's small ruminants, highlighting the need for control measures. The findings expand understanding of animal trypanosomiasis in Brazil and underscore the vulnerability of small ruminant production systems to this neglected disease.