The connection between climate change and malaria

On September 23, United Nations Secretary-General Ban Ki-moon will convene global leaders from governments, businesses, and non-governmental groups for a Climate Summit to spur action to address the climate challenge.

Is there a connection between climate change and malaria? This is an extremely complex question and we do not yet understand it completely. What we do know is that malaria is climate sensitive. There is an important balance of temperature, rainfall, and humidity that creates ideal conditions for mosquitoes to breed and to transmit malaria parasites. This is much of the reason why we see malaria thrive in tropical climates and not in deserts or arctic areas.

Temperature affects how long mosquitoes live, how quickly they mature to adulthood, how often they bite, and ultimately how many mosquitoes are around. It also affects how quickly the malaria parasite inside of a mosquito becomes mature enough to infect humans.

Rainfall creates pools of water which are essential to mosquito breeding as mosquito eggs must be laid in water and mosquito larva mature in water. In places where the burden of malaria is the greatest, the rainy season is also known as the malaria season.

Humidity, which is related to rainfall, increases the lifespan of mosquitoes, giving them more opportunities to carry malaria infections from one person to another.

While we know that climate can affect malaria transmission, the impact of climate change on regional and global malaria cases and deaths is even less understood. Some studies have shown that an increase in temperature has allowed the introduction of malaria into higher altitude areas in Kenya, Colombia, and Ethiopia, where it was previously too cold for the disease to thrive. This has put millions of people at risk for the disease.

On the other hand, a study of malaria and climate showed that despite significant increases in temperature during the 20th century, malaria rates actually decreased. But the decrease in malaria rates was mainly due to concentrated efforts by the global community to control and eliminate the disease.

So despite improved conditions for malaria transmission, mankind has managed to put up a good fight against the disease thus far. As we work to accelerate the fight against malaria, we need all of the help we can get. Reversing the effects of climate change could help us make even more progress.

While we don’t fully understand the relationship between malaria and climate change, we do know that extreme changes in temperature, rainfall, and humidity will require us to adapt our strategies to combat malaria. This will put even more pressure on already under-resourced malaria control programs. It’s time for us all to start taking climate action – and ultimately it could aid us in ending malaria for good.