From April 1984 to March 1985, a Trypanosoma lewisi
prevalence of 21.7% was found in 429 Rattus norvegicus
trapped in Belo Horizonte, State of Minas Gerais, Brazil. The infection rates were higher in male and young rats and could be attributed to ecological and behavioral factors. T. lewisi
was observed in rats measuring between 60 and 250 mm. Data about monthly T. lewisi
infections throughout the year are presented for the first time in Brazil, with the highest prevalences observed in the warm-rainy season (October to March).