The epidemiology of malaria in southern Sierra Leone.

The epidemiology of malaria was investigated in a high rainfall, forested area of southern Sierra Leone. The prevalence rates of P. falciparum, P. malariae and P. ovale in 0-7 year old children, during two surveys conducted over a 12-month period, averaged 61%, 12% and 1% respectively. Groups of febrile children had higher prevalence rates than afebrile groups. Overall, gametocyte rates were approximately one fifth of the trophozoite rates. Malaria accounted for 27% of deaths, as did malnutrition, although no malaria associated deaths occurred in 0-12 month olds. Spleen rates were similar to P. falciparum prevalence rates, and the size did not appear to be related to parasite load at the time of the surveys. Packed cell volumes had normal distributions, with a lower mode after the peak prevalence period. Chloroquine usage increased during the post-rains period compared to the pre-rains period.