The burden of malaria in Sudan: incidence, mortality and disability--adjusted life--years

Abstract

Background: Estimating the burden of malaria in Sudan is important for evidence-based planning of malaria control. Estimates of malaria burden in terms of DALYs (Disability Adjusted Life Years) were not developed locally. This study synthesized information from different sources to calculate malaria incidence, mortality and DALYs lost in Sudan in 2002.

Methods: A search for local studies and reports providing epidemiological data on malaria in Sudan was conducted. Preliminary estimates of incidence rate, case fatality rate and mortality rate were developed from the data found. The preliminary estimates were processed in the disease modelling computer software, DisMod II, to produce internally consistent mortality and incidence rates, which were used to calculate DALYs lost due to malaria.

Results: Malaria incidence in Sudan was estimated to be about 9 million episodes in 2002 and the number of deaths due to malaria was about 44,000. 2,877,000 DALYs were lost in Sudan in 2002 due to malaria mortality, episodes, anaemia and neurological sequelae. Children under five years of age had the highest burden. Males had the highest incidence and mortality, but females lost more DALYs.

Conclusion: Formal health system data underestimated malaria burden. The burden estimates can be useful in informing decision making, although uncertainty around them needs to be quantified. Epidemiological research is needed to fill data gaps and update the estimates.

Figure 1

Malaria incidence calculation model. Malaria underreporting ratio was calculated using reported episodes in 2000 and results of MICS (Multiple Indicators Cluster Survey) 2000. The number of reported episodes of presumptive malaria in 2002 in northern and southern Sudan was corrected for underreporting, and adjusted downwards to calculate true malaria incidence in each region. Age-sex ratios were used to disaggregate the overall incidence in each region and the incidence in each age-sex group was pooled to estimate the age-sex specific incidence in all Sudan.

Figure 2

Malaria case fatality and mortality calculation model. Overall case fatality ratio of severe malaria reported in a mesoendemic area was used to extrapolate the case fatality ratio in hypoendemic and hyperendemic areas, after adjusting for differences in cerebral malaria proportions between the different endemicity areas. The overall ratios were disaggregated by age and pooled for all areas in each age group. The age specific number of deaths was used to calculate age specific mortality rates and was combined with the number of malaria episodes to calculate age specific case fatality ratios and rates of malaria.

Figure 3

DALYs lost per 1000 population due to malaria in Sudan in 2002 by age and sex. In both males and females, the greatest loss of DALYs due to malaria was in children below 5 years. The burden dropped considerably in older ages. Females had a higher burden than males in all age groups.