An apparently paradoxical role for IFN-<FONT FACE="Symbol">g</font> in human Chagas' disease was observed when studying the pattern of cytokine production by peripheral blood mononuclear cells (PBMC) obtained from two groups of chagasic patients after specific stimulation with Trypanosoma cruzi-derived antigens. The groups studied were 1) patients treated with benznidazole during the acute phase of Trypanosoma cruzi infection and 2) chronically infected untreated patients. In the treated group, higher levels of IFN-<FONT FACE="Symbol">g</font> were produced by PBMC from individuals cured after treatment when compared to non-cured patients. In contrast, in the chronically infected group (not treated) higher levels of IFN-<FONT FACE="Symbol">g</font> were produced by PBMC from cardiac patients in comparison with asymptomatic (indeterminate) patients. This apparently paradoxical role for IFN-<FONT FACE="Symbol">g</font> in human Chagas' disease is discussed in terms of the possibility of a temporal difference in IFN-<FONT FACE="Symbol">g</font> production during the initial stages of the infection (acute phase) in the presence or absence of chemotherapy. The maintenance of an immune response with high levels of IFN-<FONT FACE="Symbol">g</font> production during the chronic phase of the infection may favor cure or influence the development of the cardiac form of the disease

Foi realizado um estudo sobre o T. sordida em ambiente silvestre em duas diferentes regiões do estado de Minas Gerais: Itapagipe (Triângulo), área de cerrado modificado para formação de campos de pastagem e agricultura, e Mato Verde (norte) uma área de transição entre a caatinga e o cerrado, profundamente desmatada nos últimos anos com a finalidade de expansão do cultivo de algodão. Em ambas as regiões, os principais ecotopos identificados corresponderam a buracos e cascas de árvores vivas ou mortas, onde a ocorrência de fontes de alimentação não é frequente. Neste ambiente, os triatomíneos utilizam-se de variadas fontes de alimentação; gambás parecem representar urna importante fonte de infecção. No norte de Minas, observou-se urna maior concentração de reservatórios e vetores em comparação com o Triângulo, o que pode explicar a maior taxa de infecção dos triatomíneos no norte. Maior atenção ao processo de domiciliação do T. sordida no norte de Minas Gerais é recomendada, onde, nos últimos anos, tem-se observado urna profunda intervenção do homem sobre o ambiente natural, paralelamente ao aumento da população deste triatomíneo nos peridomicílios.

A study was undertaken about T. sordida in the natural environment in two different regions of the state of Minas Gerais: Itapagipe (Triângulo), an area of cerrado modified by the formation of fields of pasture and agriculture, and Mato Verde (north) an area of transition between caatinga and cerrado with profound deforestation in the last years due to the expansion of cotton cultivation. In both regions the principal ecotopes identified were hollow trees and the bark of live or dead trees, where the occurrence of a food source is not frequent. In this environment, the triatomines utilize various food sources; opposums appear to represent an important source of infection. In the north of Minas, a greater concentration of reservoirs and vectors was observed than in the Triángulo which could explain the higher level of infection of the triatomines in the north. Close attention to the process of domiciliation of T. sordida in the north of Minas is recommended where an extensive intervention by man in the natural environment has occurred and where a rise in the population of triatomines in the peridomestic environment has been observed in recent years.

Em outubro de 1986, 7 a 22 dias após uma reunião em uma fazenda no estado da Paraíba, 26 pessoas apresentaram doença febril, associada a edema bipalpebral bilateral, e de membros inferiores, hepatoesplenomegalia leve, linfadenopatia e, mais raramente, a um exantema. Um menino de 11 anos apresentou arritmia atrial ao eletroeardiograma e um paciente de 74 anos desenvolveu insuficiência cardíaca aguda. Em 2 pacientes hospitalizados em São Paulo, foi estabelecido o diagnóstico de Doença de Chagas aguda por observação de T. cruzi em creme leucocitário. Em autópsia de um caso fatal foi demonstrada cardiomiopatia chagásica aguda. O xenodiagnóstico foi positivo em 9 de 14 pacientes testados. Anticorpos específicos de classe IgG foram encontrados em todos os pacientes e da classe IgM em 20 de 22 doentes examinados. Estudo epidemiológico revelou Triatoma brasiliensis nas vizinhanças desta fazenda, porem tal vetor não foi encontrado na casa onde a maioria dos hóspedes pernoitou. Observou-se alta taxa de gambás infectados por Trypanosoma cruzi. Essas observações, associadas as informações relativas aos alimentos consumidos, sugerem que a contaminação de alimentos tenha se originado de secreções de marsupiais naturalmente infectados ou de triatomíneos infectados, que poderiam ter sido esmagados durante o preparo do caldo de cana.

In October, 1986, 7 to 22 days after a meeting at a farm in Paraíba state, 26 individuals presented with a febrile illness associated with bilateral eyelid and lower limb edema, mild hepatosplenomegaly, lymphadenopathy and, occasionally a skin rash. A 11-year-old boy exhibited atrial premature complexes and a 74-year-old patient developed acute heart failure. In two patients hospitalized in São Paulo city, acute Chagas' disease was diagnosed by the demonstration of circulating Trypanosoma cruzi. At autopsy in a fatal case, acute Chagas' cardiomyopathy was demonstrated. Xenodiagnosis were positive in 9 out of 14 tested patients. A specific IgG immune response was found in all patients and specific IgM antibodies were identified in 20 out of 22 tested patients. A epidemiological survey showed the existence of Triatoma brasiliensis in the outbuildings of this farm, but none in the house where most of the guests stayed. A high rate of infection with Trypanosoma cruzi was found in opossums. These observations together with those related to the food consumed by the patients, lead the authors to suggest that the human infections resulted from oral contamination probably originating from naturally infected marsupials in the area or crushed infected bugs.