[CAPE TOWN] Climate change could reduce the population of malaria -transmitting mosquitoes in Africa by half in 2050, a modelling study suggests.

According to the study published in Malaria Journal this month (3 June), Anopheles arabiensis — a common vector of malaria in Africa — can survive in a wide range of climatic conditions.

Using data on malaria risk collected from all African countries between 1956 and 1996, researchers created a distribution model of the bug.

They estimated the distribution of A. arabiensis based on three different climate change scenarios for the year 2050 — a future with rapid population growth, uneven and slow technological change, or an improved environmental sustainability.

“In future, if we see that malaria is declining in some places, it may be due to our interventions or what is going on naturally in mosquito vectors that transmit the parasite because of changes in climatic conditions.”



John Drake, University of Georgia, United States

“Our model predicts that if any of these three climate change scenarios is realised, the result will be significant reductions in the total land area hospitable to A. arabiensis,” the researches note in the journal.

The researchers found that the distribution of A. arabiensis is expected to drop between 48 and 61 per cent by 2050 as a result of changes in temperature and rainfall.

John Drake, the study’s lead author and an ecologist from the US-based University of Georgia, says the findings offer a benchmark for interpreting diseases patterns.

“In future, if we see that malaria is declining in some places, it may be due to our interventions or what is going on naturally in mosquito vectors that transmit the parasite because of changes in climatic conditions,” Drake says.

According to the study, there would be reduced habitats for mosquitoes in West and Central Africa, and parts of Botswana, Kenya, Nami

bia, Somalia and Sudan, but the East African Rift Valley would continue to be habitable to the malaria vector.

Modest rise of mosquito population is predicted in Angola, South Africa and South Sudan.

Robert Crane, a professor of geography at the Pennsylvania State University, United States, says although all three climate scenarios produced the same predictions, caution should be used when interpreting the results.

“The relationship between climate and malaria is complex and projecting climate change in Central and West Africa is particularly difficult,” he says.

Leo Braack, a specialist in mosquito ecology at the University of Pretoria, South Africa, who was not involved in the study, says the findings may influence future antimalarial efforts.

“Our current strategy for fighting malaria deals with outdoor biting mosquitos. By focusing on diminishing those species, we are ensuring the likely vector in the future is the outdoor species,” he says.

Braack adds: “We need to strengthen our research to understand how these vectors and other disease-transmitting organisms are responding to environmental changes that are happening already”.

Link to full paper in Malaria Journal