In an endemic rural area of southeast Brazil, surveys confirmed that dogs serve as peridomestic reservoirs of Leishmania infantum. It is likely that the lack of efficient control is because presently used diagnostic tests miss positive dogs. Overall, 57% of the dogs had specific antibodies, but the canine infection was not uniformly fatal and many seropositive dogs remained asymptomatic or even spontaneously recovered. Furthermore, 42% of the human residents became leishmanin-positive reactors and 47% had positive serology at the initial survey, but our estimates also point at a high recovery rate among the infected population with time. The delayed-type hypersensitivity (DTH) reaction to Leishmania was a good indicator of resistance to infection in this particular epidemiologic situation. The lack of any significant differences in infection rates by gender or age indicate that all of the population was at an equal risk of infection and most people were infected in the peridomestic setting.