During 1992-1994, 33 malaria cases were reported in two regions in Brazil
where few sporadic atypical cases occur, most of them in home owners, who
are weekenders, while home caretakers live there permanently. Indirect
Fluorescent Antibody Test (IFAT), 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 1 the prevalence
of IFAT positive sera was 73% and 28% among caretakers, 18% and 9.6% among
home owners. In Region 2 (3 localities) no distinction was possible between
caretakers and home owners, IFAT positivity being 38%, 28% and 7%. 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.
