Animal trypanosome species of economical importance in South America include T. vivax and T. evansi. Both species are described in Brazil, Bolivia, Colombia, French Guyana, Peru, Suriname, and Venezuela. In Argentina and Guyana, only T. evansi and T. vivax are found, respectively. Our studies on T. vivax indicated that the parasite was spreading around 1.3 km per day in Bolivia. We found severe leukopenia in bovines from Pantanal (Brazil) and the Department of Santa Cruz (Bolivia). Because it can cause immunosupression, the importance of trypanosomiasis control in ensuring success of vaccination campaigns against foot and mouth disease (FMD) in the Pantanal and Bolivia should be considered. The use of one needle for several animals during FMD campaigns in Brazil and Bolivia could also contribute to the spread of T. vivax. The anticipated losses due to T. vivax could exceed $160 million, assuming there are 11 million head of cattle in the Brazilian Pantanal and Bolivian lowlands. International collaboration among research institutes is needed to deal with these diseases and parasites. Previous efforts using information technologies resulted in the creation of two discussion lists (Tryplink and Trypan), the edition of the on‐line version of Trypnews and Internet conferences.

Since little information is available on the epizootiological status of Trypanosoma evansi in SouthAmerica and particularly Brazil, we evaluated equine serum samples collected in 1993, 1994, 1995 and 1997

Trypanosoma vivax caused between 1995 and 1997 a devastating disease in Bolivian andBrazilian Pantanals. These regions are very important beef cattle breeding in Brazil andBolivia. The principal clinical signs of bovine trypanosomosis in livestock were anemia,severe leucopenia, and abortion. The purpose of the present study was to analyze the riskfactors of the natural bovine trypanosomosis in the Bolivian and Brazilian Pantanals. Weconcluded that the principal risk factors related to T. vivax transmission in the Bolivian andBrazilian Pantanals were the transportation by foot, because the conditions for acquisition ortransmission of T. vivax were greatest at the numerous resting places along the route, the useof contaminated needles during vaccinations, and transmission by tabanids during the rainyseason. The fauna contamination should be also considered.