Global warming could lead to an explosion of malaria in population centers in Africa, South America, and other regions across the world, researchers revealed Thursday.

The mosquito-borne disease already disproportionately affects poor and rural communities in the global south, killing approximately 1.2 million people a year, hitting sub-Saharan Africa the hardest. Researchers from the London School of Hygiene & Tropical Medicine and University of Michigan report in the journal Science that they are the first to uncover evidence that changes in climate push this disease to higher elevations — an outcome that is not good for humans.

Analyzing records of malaria cases in the Antioquia region of western Colombia between 1990 to 2005, as well as from the Debre Zeit area of central Ethiopia from 1993 to 2005, researchers uncovered evidence that malaria moves to higher altitudes during warmer temperatures and lower altitudes during cooler temperatures. The researchers accounted for other factors, such as drug resistance, rain patterns, and mosquito control programs.

These higher elevation areas are more densely-populated, in part because many highland cities emerged to avoid malaria, according to Menno Bouma, a co-author and a lecturer at the London School of Hygiene & Tropical Medicine, referenced in Scientific American. In Ethiopia, for example, 43 percent of the population — approximately 37 million people — live at higher elevations between 1,600 and 2,400 meters.

The study "suggests that with progressive global warming, malaria will creep up the mountains and spread to new high-altitude areas," said Boum, according to Reuters. Due to the lower exposure of these population, people living at higher elevations have lower immunity, the study notes.

The findings are limited to Colombia and Ethiopia, and the researchers say that more areas must be studied before broad trends are identified. Yet the report authors argue that these local findings imply that malaria infections will rise as the global temperature does. Says Bouma, "If you have a [disease range] contraction due to temperature increases in the drier parts of the world and an increase in the cooler parts of the world, the population affected in the cooler ends of the malaria distribution would be larger."

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