Researchers at the London School of Hygiene, and Tropical Medicine, and at the University of Michigan concluded that people living at higher elevations experienced more malaria infections in warmer years than they do in cooler years.

Each year, more than 300 million individuals are infected with malaria, a life-threatening blood disease. The symptoms of malaria include fever, chills, and flu-like illness. The mosquitoes that transmit the malaria-causing parasites, Plasmodium falciparum and Plasmodium vivax, flourish in warmer temperatures. 

The new study, published in Science, used an analysis of records from high altitudes in Ethiopia and Colombia ecologists. They say the mosquitoes tend to migrate back down to lower altitudes when temperatures decrease and that unless close monitoring occurs, then the number of individuals infected with significantly increase in the near future.

"We saw an upward expansion of malaria cases to higher altitudes in warmer years, which is a clear signal of a response by highland malaria to changes in climate," Mercedes Pascual, University of Michigan theoretical ecologist said. 

The researchers studied case records from the Antioquia region of western Colombia from 1990 to 2005 and the Debre Zeit area of central Ethiopia from 1993 to 2005. Variables like mosquito-control programs, changes in rainfall amounts and anti-malarial drug resistance was excluded. This helped the study to focus more on the response to yearly temperature changes in high altitudes.     

The researchers found that the median altitude for malaria cases changed to higher elevations in warmer years and to lower elevations in cooler years. 

"Our latest research suggests that with progressive global warming, malaria will creep up the mountains and spread to new high-altitude areas," co-author Menno Bouma, senior clinical lecturer at the London School of Hygiene & Tropical Medicine said. "And because these populations lack protective immunity, they will be particularly vulnerable to severe morbidity and mortality.”

This study was to add awareness to the 3.3 billion people who are at risk of malaria, due to the increased temperatures.

Additional Resource:

Altitudinal Changes in Malaria Incidence in Highlands of Ethiopia and Colombia