Climate change is driving malaria-bearing mosquitoes to higher ground, endangering the health of people who live 1,200 meters above sea level.
Researchers from the London School of Hygiene and Tropical Medicine and the University of Michigan, in a study, have found that many areas and land masses that used to enjoy cool temperature are now experiencing a gradual but noticeable warming. This change in temperature is causing malaria's domain to expand.
The new study, published in the journal Science, studied all malaria cases in the Antioquia region of western Colombia from 1990 to 2005 and the Debre Zeit area of central Ethiopia from 1993 to 2005. Malaria outbreaks tracked in these areas were then compared with logs of temperatures to determine if there was a direct relationship between the number of malaria cases and temperature changes in the areas. They excluded other factors that might influence malaria cases, such as rainfall that leads to increase in mosquitoes, mosquito control programs which lead to fewer mosquitoes, and resistance to anti-malarial drugs which affect statistics pertaining to malaria cases.
They found that the media altitude of malaria cases shifted to higher elevations in warmer years and back to lower elevations in cooler years. There was indeed a direct link between climate change and malaria cases.
"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 study author Menno Bouma, honorary senior clinical lecturer at the London School of Hygiene & Tropical Medicine.
The Debre Zeit region of Ethiopia has an elevation range of between 5,380 feet and 7,920 feet. Half of its entire population, or 37 million people, live in this elevated rural region, which is experiencing a gradual rise in temperature. An additional 3 million children will contract malaria every year in the region if the temperature continues to rise at 1 degree Celsius per year.
Millions of people have chosen to live in higher altitudes in order to lower their risk of malaria, as previous data have shown that malaria-carrying mosquitoes do not thrive in those altitudes. However, this is no longer the case. Because of climate change, areas with temperatures that were formerly hostile to malaria-carrying mosquitoes are now experiencing temperatures that are more inviting to these insects.
Malaria is inflicted upon a human by a single-celled Plasmodium that is transmitted by the bite of a mosquito that carries the microbe. Both the Plasmodium and the malaria-carrying mosquitoes thrive in warmer temperatures and because of rising temperatures, they can now survive at higher altitudes that used to be malaria-free.
Malaria infects more than 300 people each year and kills 600,000 people. It is one of the most common and deadly infectious diseases of the world. The World Health Organization said that in 2012, there were 207 million cases of malaria and 627,000 of them have resulted in death.