Malaria moving to higher altitudes due to climate change

Rising temperatures and climate change could put people living in the tropics at risk of contracting the mosquito-borne malaria, according to scientists who have spent two decades monitoring the deadly disease within two densely populated mountainous regions in South America and Africa.

Those residing in higher altitudes have typically not been at risk from the disease, as mosquitoes carrying the malaria parasite find it difficult to survive in the cooler air.

Professor Mercedes Pascual University of Michigan, who led the research, says: “The risk of the disease decreases with altitude and this is why historically people have settled in these higher regions.”

Health experts have spent years arguing if malaria will move because of climate change, and this is one of the only studies of its kind that demonstrates how malaria can migrate higher with a temperature increase. This puts millions of people at risk, who historically have been benefiting from living in malaria-free areas in the high-altitude tropics.

The study involved an analysis of the densely populated areas in the highlands of Colombia and Ethiopia as there were comprehensive records kept for the two of both temperature and malaria cases from the 1990s to 2005.

It was discovered that during warmer years, malaria managed to transmit into the mountains and for the years when the temperatures were cooler, the disease was restricted to lower altitudes.

“We have identified that malaria does indeed move up and down and that the movement is temperature dependent. It’s been difficult to prove and people have been questioning it now for 20 years,” said Menno Bouma of the London School of Hygiene and Tropical Medicine, who was involved in the research.

“The implications are that if this is true, and that a global warming is occurring leading to an increase in temperatures, then malaria will increase at higher altitudes where many people live. The high altitude areas in the tropics are particularly highly populated,” Dr Bouma added.

Dr Bouma says that those in the higher altitudes do not have any protective immunity as they are not exposed to malaria, meaning they could be susceptible to potentially even more serious and fatal cases of the disease.

Around half of Ethiopia’s population live at an altitude between 1,600m (5,250ft) and 2,400m, and the scientists estimate there could be a surge in malaria cases. They predict even just a 1C increase in average local temperatures will mean there will be three million children more children who will contract malaria annually.

“We have estimated that, based on the distribution of malaria with altitude, a 1C rise in temperature could lead to an additional three million cases in under-15-year-olds per year,” says Professor Pascual.

The most recent figures released by the World Health Organization show an estimated 207 million cases of malaria in 2012, resulting in about 627,000 deaths. The majority of these deaths occur among children in Africa. Clearly more work needs to be done into control efforts of the disease, getting malaria treatment and prevention methods to the millions who need them.

In addition, if you are travelling to particularly at-risk countries, The NHS Malaria Fit For Travel website offers advice about antimalarials such as Malarone and includes a map to show what other diseases are common in certain regions.