Saisonal patterns in overall and malaria mortality
Project team: Heiko Becher, Eveline Otte in Kampe, Heribert Ramroth, Gabriele Stieglbauer
Collaborators within the department: Olaf Müller
External collaborators: Ali Sié, CRSN, Nouna, Burkina Faso
Funding: DFG (SFB 544), Project Z2, Eigenmittel
Funding period: 2008 - ongoing
Previous studies from Burkina Faso and The Gambia have shown that overall mortality differs by season, possibly reflecting the effect of different malaria transmission rates. We evaluated seasonal patterns of malaria and all-cause mortality. Data from the aforementioned Nouna Demographic Surveillance System were analyzed for the period 1999 to 2003. Cause of death was ascertained by verbal autopsy.
Age-specific death rates by month of death were calculated by age group. Under five and infant mortality was 31.9 (95% Confidence Interval 30.4-33.5) and 60.6 (56.2-65.3) by 1000, respectively. For malaria the corresponding rates were 13.3 (12.3-14.3) and 23.4 (20.7-26.4). Both, infants and under five children had a significantly higher mortality in the main malaria transmission period August-October. In infants, the relative rate (RR) in the month with highest risk was 1.72 (1.4-2.1) in August for all causes and 2.44 (1.8-3.3) also in August for malaria. The corresponding results for children under five were 1.49 (1.3-1.7) in November for all causes and 1.98 (1.6-2.4) in August for malaria.
For other causes of death the highest risk was 1.65 (1.2-2.1) in November for both groups. In contrast, older people had highest rates in April (hot dry season) with RR 1.37 (1.0-1.8) for other causes and highest rates also in April with RR 1.50 (0.9-2.3) for malaria. The results showed that the increased mortality towards the end of the rainy season in children can to a large extent be attributed to malaria.