Diseases Resurfacing Thanks to Global Warming

There are visible signs of the consequences of global warming everywhere you look—ice caps melting, weather patterns becoming increasingly erratic, and animals migrating because of climate changes. One slightly less visible, though just as nerve-wracking, sign is in the form of an annoying little mosquito buzzing around your ear.

Mosquitoes and other insects have long been harbingers of disease, but global warming is allowing them to venture into the newly warmer areas and spread once uncommon ailments to unfamiliar locations. The following are five diseases that, much like Al Gore’s career, have had a comeback thanks to global warming.

Dengue Fever
The Aedes mosquito, which transmits the dengue fever virus, lives primarily in tropical and subtropical climates. Frost kills mosquito larvae and adults, effectively limiting the temperature range in which it can survive. However, with warming temperatures, the mosquitoes and the disease have expanded their range.

Aedes has been detected as far north as the Netherlands. In 1995, a town in Texas experienced a small outbreak of dengue. Chikungunya, a disease with symptoms similar to dengue and carried by Aedes mosquitoes, recently caused a 300-person outbreak in a small town in Italy. According to the World Health Organization (WHO), this is the first time a disease only seen in the tropics was found in modern Europe.

As higher altitudes become warmer, the dengue-carrying mosquito is also moving to higher ground. Normally limited to elevations of 3,300 feet, in the past three decades, the mosquito has been found at 5,600 feet in Mexico and at 7,260 feet in the Andes.

Since mosquitoes thrive in stagnant water, rainstorms and flooding, induced by climate change, have caused epidemics of mosquito and water-borne diseases. When three feet of rain fell on Mumbai in one day in 2005, the flooding caused epidemics of dengue fever and malaria, as well as cholera. 

Malaria
As is the case for dengue and chikungunya, rising temperatures have expanded the range of the Anopheles mosquito that carries malaria. Malaria is now found in highland regions in Africa, where it had previously not been detected; a WHO report found that warming caused malaria outbreaks in Rwanda and Tanzania and caused the disease to expand its range in Kenya. According to a report issued by the Harvard Medical School, malaria is not only circulating at higher altitudes; it is also maturing at a faster rate. At 68° F, the malarial protozoa take twenty-six days to incubate; at 77° F, they take half that time. Since Anopheles live only several weeks, warmer temperatures mean greater replication and transmission of the parasite.