ANTIBODIES ANTI BLOOD-STREAM AND CIRCUMSPOROZOITE ANTIGENS (PLASMODIUM-VIVAX AND PLASMODIUM-MALARIAE P-BRASILIANUM) IN AREAS OF VERY-LOW MALARIA ENDEMICITY IN BRAZIL

During 1992-1994, 33 malaria cases were reported in two regions in Bra zil where few sporadic atypical cases occur most of them in home owner s, who are weekenders, while home caretakers live there permanently. I ndirect Fluorescent Antibody Test (IFAT), with Plasmodium vivax, and E nzime Linked Immunosorbent Assay (ELISA) with repeat peptides of the c ircumsporozoite (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 negat ive. 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 1 the prevalence of IFAT positive sera was 73% and 28% among caretake rs, 18% and 9.6% among home owners. In Region 2 (3 localities) no dist inction was possible between caretakers and home owners, IFAT positivi ty being 38%, 28% and 7%. The relative percentage of positive anti-CS repeats ELISA, differed for each of the peptides among localities. Dwe llings are in the vicinity of woods, where monkeys are frequently seen . The origin of these malaria cases, geographical differences and high seropositivity is discussed.