Laboratory colonization of Anopheles aquasalis (Diptera: Culicidae) in Belém, Pará, Brazil.

Anopheles aquasalis Curry, a coastal malaria vector with a Neotropical distribution, was collected from Belém, Pará state, Brazil, and 500 adults per cage were maintained at the Instituto Evandro Chagas insectary at 26 -30 degrees C and 80 -90% RH, where they fed on a 10% domestic sugar solution and blood from white mice. Oviposition of the parental generation (P) occurred in fresh water in dark cups introduced into mosquito cages. After eclosion, 100 larvae per pan were reared in artesian well water (salinity 0.04 g liter(-10) and fed ground fish food until pupation. After force mating in the F1 generation, the eight subsequent generations were free mating. Mean larval mortality was < 1%, and the mean developmental time from eclosion to emergence was 7.7 d (F1), 7.6 d (F2), 8 d (F3), and 7.5 d (F4). The maximum daily production of pupae (from the fourth generation on) occurred on day 6 postoviposition.

Malaria vectors, epidemiology, and the re-emergence of Anopheles darlingi in Belém, Pará, Brazil.

An evaluation of malaria transmission and epidemiology in the Amazonian city of Belém over the last 70 years shows that (1) Anopheles darlingi, reported to be eradicated in 1968, reappeared in the mid 1990s, with a marked increase in abundance between 1997 to 1999 in two of three districts sampled; (2) An. darlingi and An. aquasalis are each implicated in current malaria transmission in different districts of the city; (3) mosquito species diversity (in Anopheles subgenus Nyssorhynchus) has increased from two in the 1930s to six in the 1940s to 10 in the 1990s; (4) there is no overall correlation between malaria case incidence and human population size from 1940 to 1996 in Belém; (5) however, the total number of malaria cases has increased significantly since the late 1970s and over the short term from 1993 to 1999; and (6) interestingly, the short term increases are due solely to cases of Plasmodium vivax infection; cases of P. falciparum malaria are declining (significantly for Pará state only). The reappearance of An. darlingi may be a result of the continued expansion of Belém into the surrounding forest in the 1990s. In the absence of preventative measures, we predict an increase in local outbreaks of malaria in the DAENT and DAICO districts where the population sizes of An. darlingi are increasing.

Susceptibility of Anopheles aquasalis and an. darlingi to Plasmodium vivax VK210 and VK247.

The susceptibility of Anopheles aquasalis (F3 generation) and An. darlingi (F1 generation) to Plasmodium vivax circumsporozoite protein phenotypes from a limited number of blood samples of malaria patients in Belém, state of Pará, Brazil, was examined A polymerase chain reaction was used to determine the P. vivax phenotypes in blood samples and the blood-fed infected mosquitoes were dissected and tested by ELISA. In all patient infections, more infected An. aquasalis and An. darlingi were positive for VK210 compared with VK247.

Susceptibility of Anopheles aquasalis and An. darlingi to Plasmodium vivax VK210 and VK247

The susceptibility of Anopheles aquasalis (F3 generation) and An. darlingi (F1 generation) to Plasmodium vivax circumsporozoite protein phenotypes from a limited number of blood samples of malaria patients in Belém, state of Pará, Brazil, was examined. A polymerase chain reaction was used to determine the P. vivax phenotypes in blood samples and the blood-fed infected mosquitoes were dissected and tested by ELISA. In all patient infections, more infected An. aquasalis and An. darlingi were positive for VK210 compared with VK247.

Malaria transmission

No Brasil, a malária está restrita à regiäo amazônica, onde ocorre mais de 95 por cento dos casos registrados no país. Somente as fêmeas de mosquitos do gênero Anopheles säo capazes de transmitir os parasitos da malária humana. Treze espécies de anofelinos do Brasil foram encontradas naturalmente infectadas com Plasmodium, mas somente poucas estäo envolvidas na transmissäo. Anopheles darlingi é o principal vetor de malária nas ecorregiões de savana e floresta plana enquanto que o A. aquasalis é responsável pela transmissäo desta infecçäo na área costeira. Todavia, A. deaneorum, A. oswaldoi e A. marajoara tem sido incriminados como vetores locais de malária. Controlar a transmissäo de malária na regisäo Amazônica é uma tarefa muito difícil por causa de suas características ecológicas, ambientais, sociais e econômicas. Nos últimos 10 anos, os assentamentos desordenados (invasões) têm sido uma das principais causas de disseminaçäo de malária humana nos grandes centros urbanos, como é o caso da cidade de Manaus e Belém.

A influ�ncia da salinidade no desenvolvimento e na susceptibilidade do Anopheles Aquasalis (Diptera: Culicidae) ao Plasmodium Falciparum

O An.aquasalis � o principal vetor na �rea litor�nea do Brasil. O objetivo deste estudo foi avaliar a influ�ncia da salinidade no desenvolvimento e susceptibilidade desta esp�cie ao P.falciparum. Para isso, foram realizados experimentos com �gua doce e dilui��es de �gua do mar (10. 20, 25, 50 e 100 porcento) utilizando ovos, larvas, pupas e adultos. Tanto ovos quanto larvas se desenvolveram melhor na dilui��o at� 50 porcento e pupas evolu�ram a adultos em todas as concentra��es. Os adultos provenientes das dilui��es salinas foram maiores que a �gua doce. As f�meas desta esp�cie n�o selecionaram o local de oviposi��o, pois n�o houve correla��o do npumero de ovos postos e teor de salinidade. Para avaliar a susceptibilidade, esp�cimes de An.aquasalis (desenvolvidos em �gua doce e dilui��o de 10 porcento da �gua do mar) e An.darlingi (esp�cie controle) foram colocados para alimentar em pacientes portadores de infec��o por P.falciparum. Para detec��o de oocistos e esporozo�tos foi realizada t�cnica de disseca��o de intestino e gl�ndulas salivares, respectivamente. Ambas esp�cies foram sucept�veis ao P.falciparum. Durante o estudo foram coletados 488 mosquitos que foram testados pelo ELISA. Foram encontrados naturalmente infectados An.aquasalis (4,0 porcento), An.darlingi (0,8 porcento) e An. galvaoi (0,6 porcento). Os esp�cimes de An.aquasalis foram positivos para as tr�s esp�cies de plasm�dio humano, enquanto que os de An.darlingi e An.galvaoi foram positivas apenas para P.vivax variante VK210. O An.aquasalis e An.darlingi continuam tendo papel importante na transmiss�o de mal�ria em Bel�m (AU)