Malaria and urbanization in central Africa: the example of Brazzaville. Part V: Pernicious attacks and mortality.

The current incidence of pernicious attacks and of mortality due to malaria were studied in Brazzaville. The results of this study, which concerned all the medical units of the town, were analysed in terms of previous studies on the epidemiology of malaria transmission in the various districts of the town. It was estimated that the annual incidence of pernicious attacks in children in Brazzaville is 1.15 per thousand between 0 and 4 years, 0.25 per thousand between 5 and 9 years and 0.05 per thousand between 10 and 14 years. The annual mortality due to malaria was estimated at 0.43 per thousand between 0 and 4 years and 0.08 per thousand between 5 and 9 years. These values are about 30 times lower than those expected from the results of previous studies of the mortality due to malaria in intertropical Africa. Whereas considerable differences in intensity of malaria transmission exist in the different districts of Brazzaville, the incidence of pernicious attacks and the resulting mortality are remarkably unvarying whatever the level of transmission. In particular, similar results were observed for the sector Mfilou-Ngamaba-Ngangouoni, where malaria is holoendemic with over 100 infective bites per person per year and a parasite rate of 80.95% in schoolchildren, and the central sector of Poto-Poto-Ouenze-Moungali, where malaria is hypoendemic with less than one infective bite per person every three years and a parasite rate of less than 4% in schoolchildren. These results are discussed in terms of previous observations in urban and surrounding rural areas.(ABSTRACT TRUNCATED AT 250 WORDS)