Studies on vectors of Trypanosoma cruzi in Trinidad, West Indies.

Studies on vectors of Trypanosoma cruzi Chagas were conducted during 1982-85 as part of an investigation on the epidemiological status of American Trypanosomiasis in Trinidad, West Indies. A total of 148 reduviid bugs were collected from caves, armadillo nests and at light traps, comprising four sylvatic species and totalling 120 Panstrongylus geniculatus (Latreille), two P. rufotuberculatus (Champion), twelve Rhodnius pictipes Stal and fourteen Eratyrus mucronatus Stal. A significantly higher level of infection with T. cruzi was recorded for P. geniculatus (42.5%) compared to R. pictipes (8.3%). The other two bug species were not found to be infected. P. geniculatus seems to be the most important vector in the sylvatic cycle of transmission of T. cruzi in Trinidad.

Isozyme variability and differentiation between Rhodnius prolixus, R.robustus and R.pictipes, vectors of Chagas disease in Venezuela.

Enzyme polymorphism in triatomine bugs of the genus Rhodnius (Hemiptera: Reduviidae), vectors of Chagas disease, is analysed using both starch and polyacrylamide gel electrophoresis. Out of forty-five enzymes assayed, the electromorphs of seventeen of them: AO, CA, DIA, ES, ES-A, FH, GPD, G6PD, GPI, MDH, ME, 6PGD, PGM, ACON, ACPH, LAP and SOD, involving twenty-two putative structural loci, were scorable. These gene-enzyme systems were therefore selected for routine characterization of R.prolixus Stal adults from different strains. The first thirteen enzymes, involving sixteen structural loci, were also analysed in first instar nymphs of the three species, R.prolixus, R.robustus Larrousse and R.pictipes Stal. Allelic frequencies were calculated for three R.prolixus strains: three to five loci appeared to be polymorphic. The proportion of polymorphic loci (22%) and the average heterozygosity (0.06) indicated low genetic variability, with significant differences between the strains at individual loci. Rhodnius prolixus and R.robustus were found to have identical isozymic patterns. R.pictipes was genetically well differentiated, with twelve diagnostic loci.

Resumos de comunicaçöes da 11a. Reuniäo Anual de Pesquisa Básica em Doenças de Chagas

Através de busca passiva para controle de malária foi detectado o primeiro caso autóctone de Tripanossomíase americana no Estado do Acre. A investigaçäo demonstrou ausência de domiciliaçäo triatomínea e a existência de biocenose silvestre. Foram isoladas duas cepas de Trypanosoma cruzi, uma do caso humano chamada Acre-Humana (AH), e outra de Rhodnius robustus coletados em palmeira uricuri (Attalea sp.) nas proximidades da casa, chamada Acre-Silvestre (AS). Destas foram feitos estudos visando a verificaçäo da existência de correlaçäo. Ambas mostraram-se patogênica para camundongos, infectandos 100% dos animais, quer com formas metacíclicas de triatomíneos quer com formas sanguícolas de doadores em fase aguda. As formas sanguícolas medem: 25,48u (AH), 27,90u (AS), de comprimento total médio e tem índice nuclear médio de 1,00u (AH) e 1,09u (AS). A infecçäo dos camundongos nas duas amostras é grave, com curto período pre-patente, parasitemia e altíssimaa taxa de letalidade. Em ambas cepas em fase aguda, ninhos de amastigotas säo abundantes, principalmente no coraçäo e fígado. As amostras AH e AS conferem aos animais que sobrevivem boa resistência contra infecçöes pela amostra Y. Cultivam-se em meios líquidos e semi-sólidos e infectam várias espécies de triatomíneos. Os resultados obtidos apresentaram existência de correlaçäo entre caracteres morfobiológicos e patogênicos das duas amostras estudadas