Aspectos ecológicos da tripanossomose americana: I - observações sôbre o Panstrongylus megistus e suas relações com focos naturais da infecção, em área urbana da cidade de São Paulo, Brasil

Abstract

RESUMO -São relatadas as investigações que levaram a efeito o encontro de foco natural da Tripanossomose Americana, na área ocupada pelo bairro denominado Chácara Flora, na cidade de São Paulo. Esse foco conta com o concurso do triatomíneo Panstrongylus megistus, de gambás Didelphis marsupialis e de ratos domésticos da espécie Rattus norvegicus. A presença destes últimos permite admitir maior aproximação da infecção no sentido do ambiente humano. O encontro de um espécimen adulto fêmea de P. megistus sugando ativamente o homem dentro da habitação, aliado à revisão da literatura, permite supor que não se trata de subespécie ecológica. A presença de diferenças essenciais de comportamento no norte e sul do Brasil, no estado atual dos conhecimentos, seria resultante, preponderantemente, da ação de fatôres ambientais, entre os quais, as condições climáticas. INTRODUÇÃOComo é conhecido, a distribuição do Panstrongylus megistus obedece a padrão que alia, à área geográfica, a ocupação de biótopos naturais ou artificiais. O primeiro caso, inclui ambiente essencialmente florestal, enquanto que o segundo, compreende aquele constituído pelas habitações humanas e seus anexos.Recebido para publicação em 25-2-1970.(1) Apresentado na sessão de 4-3-1970 do

Monitoring the domiciliary and peridomiciliary invasion process of Triatoma rubrovaria in the State of Rio Grande do Sul, Brazil

“…Active domestic invasion by fly- Atlantic Ocean ing adults of P. megistus is also common elsewhere in southern Brazil in the warmer months, but does not characterize domiciliation, which can only be considered after the finding of other developmental stages of the insects (eggs and nymphs) inside the houses (Forattini et al 1970). Salvatella et al (1995) emphasize that in Uruguay, adults of T. rubrovaria were only collected in the warmer months from October to March, so that the occurrence of nymphs and eggs in houses would be enough to suspect incipient domiciliation in this species.…”

Chagas' disease: the rural environment and vector control in the state of São Paulo, Brazil

“…Studies on the domiciliarity of the triatomine vectors of Chagas' disease in Brazil show that this process has been associated with the distribution of open spaces (Forattini et al, 1970 (Forattini, 1980). Studies involving the reconstruction of historical patterns of forestation in the state of São Paulo, carried out by the Conselho Estadual do Meio Ambiente (Consema, 1985), estimate that originally 81.8% of the state's total area was under forest cover, whereas this figure has now been reduced to 5%.…”

“…During this period -or, more specifically, in 1970 - Forattini et al (1970) commenced their studies, to be published in the series "Aspectos ecológicos da tripanossomíase americana" (Ecological aspects of American trypanosomiasis), including 21 articles and finished in 1984. Designed to increase scientific understanding of the role played by secondary vector species in the bioenvironment of Chagas' disease, these studies answered many of the questions raised during the course of the control program: could the interruption of natural transmission be reversed, with the secondary species T. sordida and P. megistus filling the ecological niche previously occupied by T. infestans, but now empty, thus leading to reinfestation of the old areas ?…”

“…Leaving aside the potential risks of transmission posed by these triatomines, was it acceptable for the rural population to carry on living side by side with blood-sucking insects? Forattini et al (1970) carried out studies on the mechanisms of triatomine adaptation to the human environment, using artificial ecotopes (experimental chicken coops) erected in several locations in the state of São Paulo. The chosen locations represented a range of different levels of landscape modification by humans, and were characterized by varying degress and types of triatomine distribution.…”

First report of Panstrongylus megistus sylvatic focus in municipality of Bambuí, state of Minas Gerais, Brazil

“…We conclude that an active surveillance program is necessary to contain household infestations. (Leal et al 1961, Schlempler-Jr et al 1985, Grisard et al 2000; 3: state of São Paulo (hollow trees, anfractuosities, bromeliads, palms and rock shelters) (Barretto et al 1964, Barretto 1967, Forattini et al 1970, 1977; 4: state of Rio de Janeiro (hollow trees) (Miles et al 1982); 5: state of Minas Gerais (hollow trees, tree holes, palms and burrows in the floor) (Barretto et al 1978, Neves 1979, Santos-Júnior et al 2011, the present paper).…”