Seasonal variations in child mortality during the 2014-2015 Ebola epidemic in Sierra Leone

Under-five mortality is a key indicator of child health, and a measure of the quality of healthcare in a country. Seasonality affecting under-five deaths is not well understood. We reviewed seasonal variations of mortality among infants under one year, children under five years, and stillbirths in Sierra Leone using data collected continuously during the 2014-2015 Ebola outbreak in Sierra Leone.

We used Ebola and non-Ebola death data from the 117 Call Centers, laboratory testing records, burial team records, and the Viral Hemorrhagic Fever module divided into dry and rainy seasons. Difference by sex was assessed by the Cochran-Mantel-Haenszel test. All trends were verified by the Joinpoint Regression Program, and the seasonal differences in monthly number of deaths were evaluated using Student's t-test.

The percentage of EVD-positive deaths significantly decreased from about 35 % in November-December 2014 to less than 2 % in April-June 2015 among children under five years, and from 47 % in January to less than 2 % in May 2015 among children under one year. Less than 5 % of EVD-positive deaths occurred during the rainy season. Our analysis showed a significant increase in non-Ebola deaths during the rainy season. About 60 % of deaths among children under one year and under five years, and 68 % of stillbirths, occurred during the rainy season. The trend analysis of monthly aggregated percentages showed an increase from about 5 % in months of November 2014 through February 2015 to more than 10 % in each month from May through August 2015. Seasonal differences in the monthly number of deaths records for children under one year were statistically significant in each data source.

Compared to the dry season, more child deaths and stillbirths occurred during the rainy season. This finding suggests the need to strengthen the healthcare system for children in consideration of the effects of seasonality on child mortality. Targeted interventions, such as improved healthcare access, seasonal malaria chemoprevention, and strengthening vaccination programs, may assist with efforts to mitigate the health effects of the rainy season in Sierra Leone.