ABSTRACT
During 1992-1994, 33 malaria cases were reported in two regions in Brazil were few sporadic atypical cases occur, most of them in home owners, who are weekenders, while home caretakers live there permanently. Indirect Flurescent antibody Test (IFLAT), with Plasmodium vivax, and Enzime Linked Immunosorbent Assay (ELISA) with repeat peptides of the circumsporozoite (CS) proteins of the 3 known P. vivax variants and P. malarie/P. brasilianum, were performed on 277 sera, obtained within a 5 to 10 km range of malaria cases. Very rarely did any of these donors recall typical malaria episodes. Blood smears of all but 5 were negative. One of the 5 malaria cases included in our serology was of a home owner, 1 of a permanent resident, 3 from Superintendencia de Controle de Endemias employees who went there to capture mosquitoes. In region 1the prevalence of IFLAT positive sera was 73 per cent and 28 per cent among caretakers, 18 per cent and 9.6 per cent among home owners. In region 2 (3 localities) no distinction was possible between caretakers and home owners, IFAT positivity being 38 per cent, 28 per cent and 7 per cent. The relative percentage of positive anti-CS repeats ELISA, differed for each of the peptides among localities. Dwellings are in the vicinity of woods, where monkeys are frequently seen. The origin of these malaria cases, geographical differences and high seropositivity is discussed.