Patterns of age-specific mortality in children in endemic areas of sub-Saharan Africa

Abstract

Understanding of the age- and season- dependence of malaria mortality is an important prerequisite for epidemiologic models of malaria immunity. However, most studies of malaria mortality have aggregated their results into broad age groups and across seasons, making it hard to predict the likely impact of interventions targeted at specific age groups of children. We present age-specific mortality rates for children aged < 15 years for the period of 2001-2005 in 7 demographic surveillance sites in areas of sub-Saharan Africa with stable endemic Plasmodium falciparum malaria. We use verbal autopsies (VAs) to estimate the proportion of deaths by age group due to malaria, and thus calculate malaria-specific mortality rates for each site, age-group, and month of the year. In all sites a substantial proportion of deaths (ranging from 20.1% in a Mozambican site to 46.2% in a site in Burkina Faso) were attributed to malaria. The overall age patterns of malaria mortality were similar in the different sites. Deaths in the youngest children (< 3 months old) were only rarely attributed to malaria, but in children over 1 year of age the proportion of deaths attributed to malaria was only weakly age-dependent. In most of the sites all-cause mortality rates peaked during the rainy season, but the strong seasonality in malaria transmission in these sites was not reflected in strong seasonality in the proportion of deaths attributed to malaria, except in the two sites in Burkina Faso. Improvement in the specificity of malaria verbal autopsies would make it easier to interpret the age and season patterns in such data.