Forest malaria in Bangladesh. I. Parasitology.

Malaria in the eastern forests of Bangladesh has never been controlled and has been the major source of the country-wide resurgence that has occurred since 1971. The malaria status of an isolated, forest-dwelling community was studied for 21 consecutive months. Blood examination, indirect hemagglutination testing, and detailed histories were used. Nearly 88% were found patent for Plasmodium falciparum and 70% for Plasmodium vivax at least once during the study. The population displayed characteristics of intense, annual transmission: asymptomatic patent infections, low trophozoite and gametocyte densities, and increasing antibody and decreasing parasite prevalence with advancing age. Prevalence and mean titer of antibody increased in each age group during the 7-month transmission season. Chloroquine-resistant P. falciparum was demonstrated epidemiologically.