Malaria mortality in Africa and Asia: evidence from INDEPTH health and demographic surveillance system sites

Abstract

Background: Malaria continues to be a major cause of infectious disease mortality in tropical regions. However, deaths from malaria are most often not individually documented, and as a result overall understanding of malaria epidemiology is inadequate. INDEPTH Network members maintain population surveillance in Health and Demographic Surveillance System sites across Africa and Asia, in which individual deaths are followed up with verbal autopsies.

Objective: To present patterns of malaria mortality determined by verbal autopsy from INDEPTH sites across Africa and Asia, comparing these findings with other relevant information on malaria in the same regions.

Design: From a database covering 111,910 deaths over 12,204,043 person-years in 22 sites, in which verbal autopsy data were handled according to the WHO 2012 standard and processed using the InterVA-4 model, over 6,000 deaths were attributed to malaria. The overall period covered was 1992-2012, but two-thirds of the observations related to 2006-2012. These deaths were analysed by site, time period, age group and sex to investigate epidemiological differences in malaria mortality.

Results: Rates of malaria mortality varied by 1:10,000 across the sites, with generally low rates in Asia (one site recording no malaria deaths over 0.5 million person-years) and some of the highest rates in West Africa (Nouna, Burkina Faso: 2.47 per 1,000 person-years). Childhood malaria mortality rates were strongly correlated with Malaria Atlas Project estimates of Plasmodium falciparum parasite rates for the same locations. Adult malaria mortality rates, while lower than corresponding childhood rates, were strongly correlated with childhood rates at the site level.

Conclusions: The wide variations observed in malaria mortality, which were nevertheless consistent with various other estimates, suggest that population-based registration of deaths using verbal autopsy is a useful approach to understanding the details of malaria epidemiology.

Keywords: Africa; Asia; INDEPTH Network; InterVA; malaria; mortality; verbal autopsy.

Fig. 1

Map showing participating sites, with age–sex–time standardised cause-specific mortality fractions and mortality rates for malaria.

Fig. 2

Malaria mortality rates by site, age group and period at 20 INDEPTH Network sites.

Fig. 3

Sensitivity analysis showing the effect of choosing the ‘wrong’ malaria endemicity setting (‘high’ and ‘low’ reversed) in processing VA data using the InterVA-4 model, by site.

Fig. 4

Scatter plot of age–sex–time standardised InterVA malaria mortality rates per 1,000 person-years for children aged 1–14 years versus Plasmodium falciparum parasite rate data for children aged 2–10 years, for 14 INDEPTH HDSS sites reporting malaria mortality which also had geo-referenced parasite rate data for 2010 in the Malaria Atlas Project (15). Line shows correlation, R ²=0.56. (1. Africa Centre, South Africa; 2. Agincourt, South Africa; 3. Nairobi, Kenya; 4. Purworejo, Indonesia; 5. Bandarban, Bangladesh; 6. Kilifi, Kenya; 7. Dodowa, Ghana; 8. Navrongo, Ghana; 9. Farafenni, The Gambia; 10. Ouagadougou, Burkina Faso; 11. Niakhar, Senegal; 12. Taabo, Côte d’Ivoire; 13. Kisumu, Kenya; 14. Nouna, Burkina Faso).

Fig. 5

Scatter plot of age–sex–time standardised malaria mortality rates per 1,000 person-years for adults (15 years and over) and children (under 15 years), for 17 INDEPTH HDSS sites reporting malaria mortality among adults and children. Line shows correlation, R ²=0.65.