Importância da repetição do xenodiagnóstico para avaliação da parasitemia na fase crônica da doença de Chagas

Abstract

Selecionam os em M a m b a í (GO) 303 chagásicos com sorologia reagenle, para estu do da parasitem ia, realizada através de três xenodiagnósticos fe ito s com D ipetalogaster m axim us e Triatom a infestans. D uzentos e dez (69,3% )pessoas apresentaram xenodiag nósticos positivos. O prim eiro exa m e detectou parasitem ia em 125 (41,2% )

Xenodiagnosis

“…Particularly interesting is the post mortem artificial XD performed in blood collected from corpses during autopsy, with a preliminary 30% positivity in individuals whose serological tests for Chagas disease -performed previously to XD -were positive (Lopes et al 1986); (e) technique for obtaining the substratum to be examined: abdominal compression (Schenone et al 1968a, 1969, 1974, Pereira JB et al 1989, Pereira VL et al 1989, Coura et al 1991; intestine dissection, grinding and homogenization (Perlowagora-Szumlewicz et al 1982, Bronfen et al 1989, Bronfen & Alvarenga 1991, Menezes, 1992; liquefaction of the whole insect, filtration of resultant material through cotton, and centrifugalization (Maekelt, 1964, Rohwedder et al 1970, Cedillos et al 1982a); examination of contents:individual (Cedillos et al 1982a, Pereira JB et al 1989, Bronfen & Alvarenga 1991, Coura et al 1991, Menezes et al 1992) and pooled (Schenone et al 1968a, Bronfen et al 1989); (f) apparently sensitivity of XD can be improved by the so-called xenoculture which consists in sowing the intestinal contents of the triatomine nymphs used in it in a modified LIT medium (Bronfen et al 1989); (g) reading: must be done by well trained and skilled personnel. It is highly advisable to have in mind the eventual finding of T. rangeli and/ or Blastocrithidia triatomae in the intestinal contents of triatomines (Cerisola et al 1971a, Cedillos et al 1982a); (h) interpretation of results: a positive XD in a suspected individual (clinical picture, positive serology and/or epidemiological antecedents) means T. cruzi infection and may confirm a chagasic etiology, but a negative XD no necessarily indicates abscence of the parasite and the need of repeating the exam (Freitas 1952, Castro et al 1983). …”

“…Determination of parasitemia in pre-treatment trials of chronic chagasic patients permits quantification and estimates of its levels in different clinical situations and the changes through the years (Castro et al 1983, Contreras et al 1988, Bronfen et al 1989, Bronfen & Alvarenga 1991, Menezes et al 1992, Medeiros et al 1994, Schenone et al 1995. XD also makes possible the isolation of T.cruzi strains from different infected patients (Bronfen et al 1989, Miranda et al 1994).…”

Chagas disease: criteria of cure and prognosis

“…Criteria in treated patients are problematic due to the absence of routine methods to discriminate between those who have been cured and those who have not. Indirect parasitologic tests like xenodiagnosis and hemoculture detect circulating parasites in 50-70% of cases (Cerisola et al 1972, Castro et al 1983, Chiari et al 1989, Luz et al 1994. Conventional serology (CS) tests detect antibodies directed against internal or surface components of intact T. cruzi or its extracts.…”

Comportamento da parasitemia pelo Trypanosoma cruzi em chagásicos crônicos durante 13 anos

“…Castro et al 3 realizaram três xenodiagnósticos em um grupo de chagásicos durante dois anos e Schenone et al 21 aplicaram xenodiagnósticos em um paciente durante 15 meses. O estudo mais longo da parasitemia ocorreu em um lapso de mais de 50 anos 7 17 18 mas, envolveu um único paciente.…”