New research suggests global warming could be influencing the spread of malaria.
Malaria is carried by mosquitos and affects over 300 million people every year, a University of Michigan news release reported. The illness reaches higher elevations when the weather is warmer.
Researchers looked at records from the highland regions of Ethiopia and Colombia and concluded warming temperatures would increase the rate of malaria cases in Africa and South America.
"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," U-M theoretical ecologist Mercedes Pascual, senior author of the paper, said in the news release.
"This is indisputable evidence of a climate effect," Pascual, said. "The main implication is that with warmer temperatures, we expect to see a higher number of people exposed to the risk of malaria in tropical highland areas like these."
Over 20 years ago malaria was identified as a disease that would be heavily affected by climate change because both the Plasmodium parasites that cause the illness and the carrier mosquitos do well in higher temperatures.
In recent years some researchers have argued that "socioeconomic conditions and more aggressive mosquito-control efforts" would have a greater influence on the spread of malaria than climate change.
The researchers focused on the infection's "altitudinal response to year-to-year temperature " and found the malaria infection reached higher altitudes in warmer years than it did when the temperature was cooler.
"Our latest research suggests that with progressive global warming, malaria will creep up the mountains and spread to new high-altitude areas. And because these populations lack protective immunity, they will be particularly vulnerable to severe morbidity and mortality," said co-author Menno Bouma, honorary senior clinical lecturer at the London School of Hygiene & Tropical Medicine.
In a past study the researchers determined that if the global temperature warmed just one degree Celsius there would be an additional three million malaria cases annually in the under-15 population of Ethiopia every year.
"Our findings here underscore the size of the problem and emphasize the need for sustained intervention efforts in these regions, especially in Africa," Pascual said.
