A new study found that the malaria disease can now reach areas with higher altitudes during warmer years.

According to the World Health Organization (WHO), almost half of the global population is at risk of malaria. In 2010, they were able to record 219 million cases with 660,000 deaths. Ninety percent of the death cases were from the African region.

Researchers from the University of Michigan, led by Professor Mercedes Pascual, found out that malaria is now entering regions it has not reached before. It was previously believed that the cool air surrounding the areas with higher altitudes makes it hard for the malaria parasite and mosquito carrier to survive. However, this is not the case anymore. They discovered that during warmers years, malaria moved higher into the mountains and stayed low during colder years.

"The risk of the disease decreases with altitude and this is why historically people have settled in these higher regions," Prof. Pascual told BBC News.

Scientists looked at densely populated areas in the highlands of Colombia and Ethiopia. Both areas have detailed records of both temperature and malaria cases from the 1990s to 2005.

They believe that residents of Africa and South America's highlands have higher risks of catching the disease particularly Ethiopia where nearly half of the population settles on lands with altitudes between 1,600m (5,250ft) and 2,400m.

With the looming temperature rise in the future, scientists expect millions of additional cases in some areas.

"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," said Prof Pascual to BBC.

The study suggests that the government should shift its focus on vulnerable areas and bring more effort to control the spread there than in previously affected areas.

This study was published in the March 7 issue of Science.