The epidemiology of Plasmodium falciparum malaria in two Cameroonian villages: Simbok and Etoa

In support of ongoing immunologic studies on immunity to Plasmodium falcipa rum, demographic, entomologic. parasitologic, and clinical studies were con ducted in two Cameroonian villages located 3 km apart. Simbok (population = 907) has pools of water present year round that provide breeding sites for Anopheles gambiae, whereas Etoa (population = 485) has swampy areas that d ry up annually in which A. funestus breed. Results showed that individuals in Simbok receive an estimated 1.9 and 1.2 infectious bites per night in th e wet and dry season, respectively, whereas individuals in Etoa receive 2.4 and 0.4 infectious bites per night, respectively. Although transmission pa tterns differ, the rate of acquisition of immunity to malaria appears to be similar in both villages. A prevalence of 50-75% was found in children <10 years old, variable levels in children 11-15 years old, and 31% in adults. Thus, as reported in other parts of Africa, individuals exposed to continu ous transmission of P. falciparum slowly acquired significant, but not comp lete, immunity.