Longitudinal study of naturally acquired humoral immune responses against the merozoite surface protein 1 of plasmodium vivax in patients from rondonia, brazil - Mertens, F; Levitus, G; Camargo, Luís Marcelo Aranha; Ferreira, Marcelo Urbano; Dutra, A P; Del Portillo, Hernando Antonio (American Journal of Tropical Medicine and Hygiene, 1993)