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Anophelines collected indoors and in the peri-domiciliary area in 3 localities in the Amazon region, state of Acre, Brazil, from August 1990 to January 1991 were examined by enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies directed against the repeats of the circumsporozoite proteins of Plasmodium falciparum, P. vivax, P. vivax V247, and P. malariae. Of the 3056 specimens collected, 2610 were Anopheles oswaldoi, 362 A. deaneorum, 60 A. triannulatus and 24 were A. darlingi. The infection rates of A. oswaldoi were 3.41% for P. falciparum, 2.26% for P. vivax, 1.22 for P. vivax VK247, and 0.42% for P. malariae. For A. deaneorum, the infection rates were 2.76% for P. falciparum, 0.55% for P. vivax, and 0.82% for P. vivax VK247. All samples of the other 2 species collected (A. triannulatus and A. darlingi) were negative in the ELISA. There were certain differences in the anopheline distribution and infection rates between these localities, and in one only A. oswaldoi was found to be infected. These results strongly point to A. oswaldoi as the main malaria vector in the region. No difference was found between the potential vectors of P. vivax and P. vivax VK247. The significance of these findings for malaria control is discussed.

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Antibodies against the Plasmodium vivax-like/P. simiovale malaria parasite circumsporozoite repeat peptide (APGANQEGGAA)3 were determined by enzyme-linked immunosorbent assay (ELISA) in 120 sera randomly collected in 1994 from adults in 3 localities of the malaria endemic area in the State of Acre, Brazil; antibody was detected in 18 (15%). A 'sandwich' ELISA using monoclonal antibody (mab) Pam 172, directed against the same peptide, was carried out on 1207 Anopheles oswaldoi, 12 of which (1.0%) were positive, and 168 A. deaneorum, 2 of which (1.2%) were positive. This is the first report of serological detection of the P. vivax-like parasite in anophelines and the first report linking anopheline to human serology for this parasite in the same geographical area. It is an additional indication that A. oswaldoi is a malaria vector in Acre.

The aim of the present work was to establish appropriate criteria for screening of donor blood from regions with distinct Malaria epidemiological characteristics. Three locations with different screening criteria were studied: São Paulo, SP (with no vectorial transmission), Belém, PA (with low active transmission) and Matupá and Peixoto de Azevedo, MT (with high active transmission). The Malaria parasite--Plasmodium sp--was searched for by "thick film", QBC Test and antigen Immunofluorescence test, and was not detected in any of the samples. There was, however, a great variation in the positivity of anti-plasmodial antibodies, as determined by IIF-IgG anti-P. vivax and -P. falciparum, between accepted donors in the 3 studied locations and between rejected and accepted donors in São Paulo (1.98% accepted, 22.3% rejected--p < 0.01) and Belém (17.2% accepted, 58.3% rejected--p < 0.01). These data endorse the use of the applied clinical and epidemiological screening. In Matupá and Peixoto de Azevedo, where there was no rejected donor, the serological positivity was 80.6%. We, therefore, consider that the Malaria screening in blood banks should follow clinical and epidemiological criteria suitable to each region. The laboratorial screening techniques should then detect either the parasites (thick film/QBC Test or the parasite antigens.

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