Santo Inácio revisited: protozoan diseases in an isolated village in northeastern Brazil after twenty years.

The northeastern highlands of Brazil are endemic for several tropical diseases, especially American trypanosomiasis (Chagas' disease) and schistosomiasis. Twenty years ago, we measured the seroprevalence of protozoan diseases in Santo Inácio, a village of approximately 1,000 inhabitants located 1,000 m above sea level. We detected small numbers of sera with antibodies against Trypanosoma cruzi and Toxoplasma gondii, and the area had a low prevalence both of American trypanosomiasis (3.54%) and toxoplasmosis (27.43%) compared with nearby Brazilian areas. This was attributed to a specific triatomine vector and local housing conditions. Twenty years later, we again determined the prevalences of both diseases and compared these results with those from Iraquara, a larger town with the same ethnic and social background but with a higher prevalence of rural activities. The incidence of Chagas' disease in San Inácio showed the same low level, i.e., 3.78% (5 of 132) with only adult males affected in contrast with Iraquara, which had an incidence of 34.5%, but a low prevalence of only one of 22 among children up to 14 years of age. Santo Inácio maintained a low (25.8%) seroprevalence for toxoplasmosis. Housewives presented a higher incidence of toxoplasmosis during both periods, probably due to related risk factors. Cats were found less frequently in Santo Inácio than in Iraquara, which showed an incidence of 65.5% seropositivity for Toxoplasma gondii. These results suggest that the environmental conditions of Santo Inácio were preserved after 20 years, with a low incidence of these selected protozoan diseases.

Experimental toxoplasmosis, and immunosuppression (parasite evaluation and histological alterations)

With the purpose of studying immunosuppressant drug action on parasites, the effect of Cyclosporine and cortisone in experimental toxoplasma evaluation, a highly virulent strain of Toxoplasma gondii (RH strain) was used. The animals were divided in two groups: control and immunosuppressed. Two animals from each group were sacrificed daily. Evaluation was based on parasitemia and parasitism of peritoneal exsudate and presence of the parasite in heart, lung, liver, spleen, small bowel, brain, cerebellum, spinal cord and eyes. Parasite infestation in peritoneal exsudate was 10 times greater than parasitemia. Red spots were observed after the second day; after the fourth day, focal necrosis with softening and fluidification of brain tissue spattered throughout the nervous tissue with enhanced vascularization. Capillaries obstructed by Toxoplasmas gondii were found, causing infarction and necrosis due to toxic or enzymatic substances. Images suggestive of cells an "owl-eye", Cytomegalovirus-like were found, with T. gondii, both in the brain, as well as in the tear glands and small bowel. Blood stream parasite infestation was observed, no histopathological lesions were found in the remaining tissue, possibly due to lack of time, for all animals died within a week's observation. We conclude that immunosuppression has worsened the outcome, anticipating the disease in 24 hours.