Climate drivers of malaria seasonality and their relative importance in
Sub-Saharan Africa
Abstract
A new database of the Entomological Inoculation Rate (EIR) is used to
directly link the risk of infectious mosquito bites to climate in
Sub-Saharan Africa. Applying a statistical mixed model framework to
high-quality monthly EIR measurements collected from field campaigns in
Sub-Saharan Africa, we analyzed the impact of rainfall and temperature
seasonality on EIR seasonality and determined important climate drivers
of malaria seasonality across varied climate settings in the region. We
observed that seasonal malaria transmission requires a temperature
window of 15-40 degrees Celsius and is sustained if average temperature
is well above the minimum or below the maximum temperature threshold.
Our study also observed that monthly maximum rainfall for seasonal
malaria transmission should not exceed 600 mm in west Central Africa,
and 400 mm in the Sahel, Guinea Savannah and East Africa. Based on a
multi-regression model approach, rainfall and temperature seasonality
were significantly associated with malaria seasonality in most parts of
Sub-Saharan Africa except in west Central Africa. However, areas
characterized by significant elevations such as East Africa, topography
has a significant influence on which climate variable is an important
determinant of malaria seasonality. Malaria seasonality lags behind
rainfall seasonality only at markedly seasonal rainfall areas such as
Sahel and East Africa; elsewhere, malaria transmission is year-round.
The study’s outcome is important for the improvement and validation of
weather-driven dynamical malaria models that directly simulate EIR. It
can contribute to the development of malaria models fit-for-purpose to
support health decision-making towards malaria control or elimination in
Sub-Saharan Africa.