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During the last twenty years, several adults of Triatoma tibiamaculata infected with Trypanosoma cruzi have been spontaneously caught by inhabitants, inside their houses in the new habitational district of Pitua¿u of Salvador, Bahia. In this communication the authors call attention to the necessity of studies about the possibility of occurrence of new human cases of Chagas disease, to clarify the obscure origin of some positive blood donors in Salvador.

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From July to September of 1998, 152 fleas were collected from 18 specimens of the fox Cerdocyon thous captured in the visceral leishmaniasis endemic area of Jacobina, State of Bahia, Brazil. The fleas were identified as: 136 Rhopalopsyllus lutzi lutzi, 11 Pulex irritans, 2 Ctenocephalides canis, 1 Ctenocephalides felis felis and 2 Xenopsylla cheopis.

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The laboratory and field observations summarized in this paper on visceral leishmaniasis ecology in the State of Bahia, Brazil are based on the author's observations over the past 35 years in a number of state's foci, public health records and literature citations. The disease is endemic with epidemic outbreaks occurring every ten years and its geographical distribution is expanding rapidly in the last years. Leishmania chagasi is the main ethiologic agent of the visceral leishmaniasis but Le. amazonensis s. lato was the only leishmania isolated by other authors from some visceral leishmaniasis human cases in the state. Lutzomyia longipalpis (with one or two spots on tergites III and IV and two sized different populations) was epidemiologically incriminated as the main vector. It was found naturally infected with promastigotes, and it was infected with four species of leishmanias in the laboratory. Although the experimental transmission of Le. amazonensis by the bite of Lu. longipalpis to hamsters was performed, the author was not successful in transmitting Le. chagasi in the same way. The dog is the most important domestic source for infection of the vector, however it is not a primary reservoir. The opossum Didelphis albiventris was found naturally infected with Le. chagasi but its role as reservoir is unknown. Foxes and rodents were not found infected with leishmanias in Bahia.

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Preliminary data of a project about the ecology of the Phlebotominae (sandflies) in a tegumentary leishmaniasis area of coconut plantation in the south of the State of Bahia, Brazil are presented. There are 60 dwellings far of one another, where existed 31 dogs and 229 inhabitants. Among them 41.5% were Montenegro positive; 37.5% from these had scars of healed ulcers and 8.8% had active ulcers. 53% of the house had dogs from which 22% were seropositive; from the 7 dogs with ulcers only 3 were seropositive. 14% of the inspected house harboured sandflies inside them. During two years of observations 72 sentinels hamsters were maintened at houses of patients with leishmaniasis ulcers, but they did not get the infection. During two years of observation, monthly collectings of sandflies were made inside house, chicken pen, curral, tree trunks and open field around a house with a patient with leishmaniasis. The following results were already obtained about the vectors: 5,614 specimens were identified as belonging to fourteen different species of sandflies. Among them Lutzomyia whitmani (92%) and Lutzomyia intermedia (4.8%) were the most abundant species. They are very anthropophilic and can be found inside houses and at peridomestic sites. Probably they are the principal vectors of the disease at domestic places. The other twelve species were less frequent and more found at sylvatic places in inspite they also bite the man. Generally the biting activity of most of the species of the area begins at 5 p.m. in the dusk and reaches its peak at 0 hour a.m., when begins declining until disapear at 7 a.m. L. whitmani was similarly collected with the same density in all lunar phases while L. intermedia was more abundant during the new moon phase. Most of the hundreds sandflies collected during the second year of observations, remains preserved in liquid nitrogen, watching for the adjustment of PCR molecular techniques to be processed for determination of the vector natural infection rates with leishmanias. Final results on all the project will be published as soon as the examination of such material has been processed.

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Durante os anos de 1982 a 1986, a investigaçäo sobre mamíferos comensais e silvestres, da periferia da cidade de Jacobina, Bahia, mostrou, ao lado do escasso número de exemplares, uma reduzida variedade específica dessa fauna. Capturou-se apenas 11 espécies, entre as quais, predominou o Didelphis a albiventris, que abrangeu 44% dos 213 espécimes capturados Didelphis albiventris, que abrangeu 44% dos 213 espécimes captura capturados. Entre os 193 com exames já concluídos, 84 eram exemplares de D. albiventris e 2 estavam infectados pela Leishmania donovani senso lato, 1 por L. mexicana amazonensis, 1 por L. braziliensis, subespécie e 3 por Trypanosoma cruzi. Também foram observadas formas suspeitas de serem amastigotas de leismanics, nos esfregaços de órgäos de 3 exemplares de Dasyprocta aguti, 1 Cercomys cunicularius-e 1 Oryzomys eliurus. O restante dos exemplares, inclusive 14 de Lycalopex vetulus, estava negativo para flagelados. Apesar de reforçado por outros indicadores epidemiológicos, como a predominância específica, a freqüência domiciliar, a atratividade para a vetora Lutzomya longipalpis, e a concomitância com casos humanos nos mesmos locais, o índice de 2,3% de infecçäo natural do Didelphis albiventris, näo autoriza a conclusäo definitiva de ser o marupial o mais importante reservatório natural da leishmaniose visceral em Jacobina

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Foi usado um teste imunoenzimático competitivo para investigar a presença de anticorpos anticomponente 5 nos soros de sariguês, cäes, coelhos e ratos infectados com o Trypanosoma cruzi. Neste teste, foi utilizado um anticorpo monoclonal contra o antígeno 5 que é específico do T. cruzi. Também foram testados os soros de 51 pacientes venezuelanos com doença de Chagas. Apesar desses anticorpos näo serem detectados nos soros de cäes, ratos e sariguês infectados com o T. cruzi, alguns soros de coelhos infectados apresentaram resultados positivos porém em níveis próximos aos do limite de positividade do teste. Esses achados surgerem que a resposta imune em animais naturalmente ou experimentalmente infectados com o T. cruzi é diferente daquela que é observada na doença de Chagas humana

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An outbreak of 20 cases of acute Chagas' disease followed the movement of Triatoma infestans into the county of Riacho de Santana, Bahia, Brazil. The outbreak was unusual in that the majority of cases occurred in adults. Vector control measures were implemented. Three years after the outbreak, a rural community was examined to determine the extent of human infection and disease due to Trypanosoma cruzi. Ninety of 440 residents (20.5%) had serologic evidence of infection, but rates of electrocardiographic (EKG) abnormalities were low. Comparison of age-specific rates of seropositivity and EKG abnormalities with rates from areas with endemic Chagas' disease supported the hypothesis of a recent epidemic. Control measures appear to have interrupted transmission in the region.

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Ectoparasites collected from wild mammals of Ilha Grande, state of Rio de Janeiro, Brazil, are listed. The most frequent species of mammal was Proechimys dimidiatus (Gunther, 1877); Gigantolaelaps oudemansi Fonseca, 1939 and Polygenis lakoi Guimarães, 1948 were the predominant species of acari and fleas, respectively.

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We studied the association between human incidence of Trypanosoma cruzi infection and household infestation density of Panstrongylus megistus in Castro Alves, Bahia, Brazil. During a 9-year period, 19 persons seroconverted; 17 were children, 17 lived in nonplastered houses, and 13 lived in houses infested with triatomines. Although 6 seroconverting persons lived in houses where triatomines could not be found, the risk of seroconversion was significantly greater in infested houses and 16 times greater in densely infested houses (greater than 15 bugs/person-hour of search). The highest rate of seroconversion (6/100 person-years exposure) occurred in houses containing the greatest number of bugs infected with T. cruzi (greater than 6 infected bugs/person-hour). These observations suggest that vector control measures could have a dramatic impact on transmission of T. cruzi by P. megistus.

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Adult triatomine insects, Panstrongylus megistus, naturally infected with the protozoa, Trypanosoma cruzi, contained significantly more metacyclic trypomastigote forms in their digestive tracts than did P. megistus nymphs. Metacyclics were scarce in all stages of triatomines fed once on infected mammalian hosts and subsequently starved. In contrast, triatomines fed repeatedly on infected mammalian hosts developed prolific T. cruzi infections. Repeatedly fed adults contained 14 X more metacyclics than similarly fed nymphs. Nutritional factors appear to play a key role in regulating metacyclogenesis. Control campaigns designed to alter the age structure of populations of triatomines must take notice of the high transmission potential of the adult stage.

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An opossum, Didelphis albiventris, from Jacobina, Bahia State, was found naturally infected with Leishmania donovani, being the first non-canid wild mammal to be detected with the agent of kala-azar in the New World.

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The relationship of symptoms and radiographic abnormalities suggestive of esophageal motility disorders with electrocardiographic (ECG) alterations and seroreactivity to Trypanosoma cruzi was studied in a defined population in a rural area endemic for Chagas' disease in Bahia, Brazil. Between January and June 1981, 680 individuals 5 years of age or older were examined with serologic tests, ECGs and questionnaires for esophageal motility disorder. Of these, 39.9% were seropositive for Chagas' disease. Symptoms of dysphagia occurred 2.5 times more frequently among seropositive individuals than among seronegative individuals. Radiographic esophageal abnormalities were 3.6 times more frequent among seropositive individuals than among seronegative individuals in the symptomatic group. Symptoms and radiographic abnormalities were more common in men than in women although this was not statistically significant. Among seropositive individuals the percentage with symptoms of dysphagia increased with age, with a peak prevalence rate of 23.9% in the 45- to 64-year-old age group. Also, in the seropositive group, 41.7% with X-ray abnormalities of the esophagus and 26.3% with symptoms of dysphagia presented an abnormal ECG.

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Foram comparados quatro metodos para detectar a infestacao dos domicilios por triatomineos: 1)coleta manual; 2) coleta manual apos a aplicacao de piretro; 3)procura de ovos viaveis; 4)caixas de GomezNunez. A coleta manual foi o metodo mais sensivel (23% de infestacao), seguido da aplicacao de piretro (21%), das caixas de Gomez-Nunez(15%) e finalmente dos ovos via veis (12%). Cerca de 10% das casas infestadas foram exclusivamente positivas no teste das caixas de Gomez-Nunez.Ainda mais 6 das 7 casas positivas exclusivamente pelo metodo de Gomez-Nunez estavam localizadas numa area recentemente borrifada, onde a densidade de Panstrongylus megistus era muito baixa. A inspecao das caixas de Gomez-Nunez 12 semanas apos a aplicacao de inseticida foi duas vezes mais efetiva do que a inspecao 6 semanas apos a aplicacao de inseticida. As manchas de fezes eram as evidencias mais comuns para indicar a presenca de P. Megistus dentro da caixa de Gomez-Nunez. A caixa de Gomez-Nunez e um complemento util da coleta manual para detectar a infestacao domiciliar pelo P. megistus, especialmente nas areas onde a den sidade de triatomineos e baixa. Contudo, a utilidade das caixas de Gomez-Nunez deve ser levada em consideracao com referencia ao tempo e trabalho que requerem

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Experimentamos o novo inseticida bendiocarb para o combate ao Panstrongylus megitus, principal vetor da doenca de Chagas, em uma area endemica do Estado da Bahia, Brasil. Uma das partes da experiencia constou da aplicacao de 0,4 g/m2 de bendiocarb a 80% pelas equipes de guardas borrifadores oficiais. A taxa de infestacao das casas foi reduzida de 18% para 7%, seis meses apos a aplicacao do inseticida, e a densidade de P. megistus caiu de 7 para 1,5 exemplares por hora. A outra parte constou da utilizacao da mao-de-obra dos habitantes na inspecao de suas casas para triatomineos, da aplicacao por meio de uma pequena bomba manual, de bendiocarb a 20% sempre que observassem triatomineos. A taxa de infestacao das casas foi reduzida de 48% para 14% e a densidade de P. megistus caiu de 12 para menos de 1 exemplar por hora. Apesar da concentracao mais fraca, o bendiocarb aplicado com a colaboracao da populacao, apresentou resultados mais eficientes, provavelmente devido a constante vigilancia com que ficou a area, havendo consequentemente, maior frequencia na aplicacao do inseticida. O metodo de combate aos vetores com a participacao da populacao mostrou-se mais eficiente e menos dipendioso. Dessa forma, se adotado pelos servicos de combate as endemias no Brasil, talvez venha a ser a solucao para o descontinuidade das campanhas contra a doenca de Chagas

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