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.

Avaliação de Hb A2 e Hb F em doadores de sangue de região malarígena da Amazônia Oriental brasileira por HPLC / Evaluation of Hb A2 and Hb F by HPLC in blood donors from the malaria endemic region of Eastern Amazon of Brazil

In malaria endemic regions of Africa, resistance to infection by Plasmodium has been observed in under 6-month-old children, when there are higher fetal hemoglobin (Hb F) levels. Research performed in the São José do Rio Preto region, central-east Brazil, reported increased levels of Hb F in blood donors. The purpose of this work was to evaluate the A2 hemoglobin (Hb A2) and Hb F concentrations in blood donors deriving from the Brazilian malaria endemic region. Forty-five blood donor samples from Macapá, from patients with varying genders, ages and ethnic origins, were collected by venous puncture after informed consent was obtained. The samples were analyzed by High Performance Liquid Chromatography (HPLC) - System Variant (Bio-Rad). The HPLC demonstrated sensitivity and rapidity in the identification and measurement of the hemoglobins and gave precise results. Moreover, it provided measurement of hemoglobin variants, even when they were present in small amounts, providing a diagnosis of hemoglobinopathies. Hb F levels above the normal were observed in 33.3 percent of the analyzed samples. The presence of increased Hb F can suggest resistance to infection by Plasmodium falciparum, as there have been reports that infected red blood cells interfere in the development of the parasite.

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.