Deltamethrin impregnated bednets for the control of urban malaria in Kumba Town, South-West Province of Cameroon.

ABSTRACT

PIP: In 1992, in Cameroon, 40 households in two neighborhoods of Kumba, located in the rain forest region of the South-West Province, were randomly allocated to either the group that received deltamethrin impregnated bednets or the group who received no bednets. Each group had about 240 persons aged 15 years or under. The neighborhoods were Kossala (high malaria prevalence) and Mbonge Road (low prevalence). Parasitological, entomological, and clinical studies were conducted longitudinally so researchers could determine whether deltamethrin impregnated bednets would cause a reduction in malaria morbidity and parasitic indices. The geometric mean parasite density (GMPD) decreased with age, especially for 11-15 year olds, suggesting acquired immunity. The deltamethrin group was more likely than the control group to have lower malaria prevalence (29% vs. 41%; p = 0.002), spleen rates (18.5% vs. 30.4%; p = 0.009), and spleen sizes (p = 0.0002). GMPD was also lower, but not significantly so (764 vs. 1081/mcl). During the rainy season (April, June, and August), malaria prevalence was not statistically significant between the test and control groups. In Kossala, children aged 6-10 years had a higher malaria prevalence rate than other age groups. The deltamethrin impregnated bednets afforded better protection in Mbong Road than in Kossala, suggesting that they are most effective in areas of low malaria endemicity. The significant reductions in human/vector contact were relatively low when compared with earlier studies mainly conducted in rural areas. Parents and children in urban areas such as Kumba tend to stay up late (e.g., watching TV) and probably receive many mosquito bites while awake. Impregnated window curtains may improve protection in malaria endemic urban areas.