Image copyright Science Photo Library Image caption Malaria parasites - seen here infecting red blood cells - and mosquitoes do not like cold temperatures 
 
 Warmer temperatures are causing malaria to spread to higher altitudes, a study suggests. 
 
 Researchers have found that people living in the highlands of Africa and South America are at an increased risk of catching the mosquito-borne disease during hotter years. 
 
 They believe that temperature rises in the future could result in millions of additional cases in some areas. 
 
 The research is published in the journal Science. 
 
 Prof Mercedes Pascual, from the University of Michigan in the US, who carried out the research, said: "The impact in terms of increasing the risk of exposure to disease is very large." 
 
 Vulnerable to disease 
 
 Areas at higher altitudes have traditionally provided a haven from this devastating disease. 
 
 This expansion could in a sense account for a substantial part of the increase of cases we have already observed in these areas Professor Mercedes Pascual, University of Michigan 
 
 Both the malaria parasite and the mosquito that carries it struggle to cope with the cooler air. 
 
 Prof Pascual said: "The risk of the disease decreases with altitude and this is why historically people have settled in these higher regions." 
 
 But the scientists say the disease is entering new regions that had previously been malaria-free. 
 
 To investigate, scientists looked at densely populated areas in the highlands of Colombia and Ethiopia, where there are detailed records of both temperature and malaria cases from the 1990s to 2005. 
 
 They found that in warmer years, malaria shifted higher into the mountains, while in cooler years it was limited to lower elevations. 
 
 "This expansion could in a sense account for a substantial part of the increase of cases we have already observed in these areas," said Prof Pascual. 
 
 Image copyright Science Photo Library Image caption The highlands of Ethiopia could be more vulnerable to malaria if temperatures rise 
 
 The team believes that rising temperatures could cause a further spread. 
 
 In Ethiopia, where nearly half of the population live at an altitude of between 1,600m (5,250ft) and 2,400m, the scientists believe there could be many more cases. 
 
 "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. 
 
 The team believes that because people living in areas that have never been exposed to malaria are particularly vulnerable to the disease, attempts to stop the spread should be focused on areas at the edge of the spread. The disease is easier to control there than at lower altitudes where it has already established. 
 
 According to the latest estimates from the World Health Organization, there were about 207 million cases of malaria in 2012 and an estimated 627,000 deaths. Most deaths occur among children living in Africa. ||||| Malaria is one of the most common—and deadly—infectious diseases in the world, sickening more than 300 million people a year and killing over 600,000 people . But because it's a mosquito-borne disease—the parasite that causes malaria is passed to human beings by mosquito bites—its range has been limited to warmer tropical areas, the so-called "malaria belt." And even within tropical countries, altitude matters: the disease is much less common in tropical highlands, where colder temperatures slow down both the mosquito and the development of the parasite within it. It's not for nothing that 19th century British colonists would build hill stations in malaria-prone countries like India, to escape both heat and disease. 
 
 So it's not surprising either that scientists have been trying to find out for years whether climate change might expand the range of malaria, putting millions of people who live in tropical highlands at risk. Warmer temperatures should mean more malaria, but in recent years the number of cases has actually fallen dramatically , largely because of renewed efforts to fight the disease. But now a new study in Science makes a strong case that as the climate warms, malaria will indeed be on the march, expanding its range to previously safe high-altitude territory, putting even more pressure on prevention campaigns—and if those fail, leading to more deaths. 
 
 Researchers from the London School of Hygiene and Tropical Medicine and the University of Michigan sifted through regional records in Ethiopia and Colombia, two tropical countries with highland territory, looking at malaria cases from 1990 to 2005 in Colombia and 1993 to 2005 in Ethiopia. They corrected for other factors that might influence malaria cases—mosquito control programs, for example, which lead to fewer of the insects; and rainfall, which leads to more—and found that the median altitude of malaria cases moved higher in warm years, and lower during cooler yields. All else being equal, as the planet warms, it seems likely that malaria will become more dangerous to more people. 
 
 "This is indisputable evidence of a climate effect," said Mercedes Pascual, a disease ecologist at Michigan and one of authors of the Science paper. "Our findings here underscore the size of the problem and emphasize the need for sustained intervention efforts in these regions, especially in Africa." 
 
 One thing that will make the problem worse is that people who live in tropical highlands tend to be much more vulnerable to malaria parasites to begin with because they've never been infected before. In an earlier paper, the Science researchers estimated that a 1° C (1.8° F) temperature increase could lead to an additional 3 million malaria cases in Ethiopian children, assuming control methods weren't strengthened. And that's the key point. While global warming will put more people around the world at risk for malaria and other tropical diseases, climate is far from the only factor at work. Developed cities like Singapore are well within the malaria belt, but the disease has been virtually eradicated there thanks to stringent control methods. Malaria was rampant in U.S. states like Georgia as late as the 1920s, but it's long gone now , eliminated by control efforts that led to the creation of the Centers for Disease Control. And even in Africa, malaria incidences have fallen by 31% since 2000— as the climate has warmed—and globally 3.3 million malaria deaths have been avoided thanks to the work of institutions like the Gates Foundation . Malaria, like many infectious diseases, is first and foremost a problem of development and poverty—and when those are addressed, infections fall. 
 
 But by expanding the range of malaria, climate change will make a tough challenge all the more difficult. It's just one more way carbon can kill.
– Efforts to eradicate malaria are going to be hit hard by rising temperatures that open up new altitudes to the mosquitoes that carry the disease, researchers warn. Both mosquitoes and the malaria parasite struggle in chillier temperatures, and a new study has found that the disease climbs to higher elevations in warmer years, the BBC reports. In areas like the highlands of Colombia and Ethiopia, people have never been exposed to malaria, making them especially vulnerable to the spread of the disease. "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," one of the researchers warns. Malaria infects more than 200 million people per year and kills around 600,000 of them, mainly children in Africa. But climate isn't the only factor at work in its spread, with the biggest advances in malaria control coming alongside efforts to combat poverty, Time notes.