Mosquito Season Getting Longer

By Climate Central

Since the 1970s, temperatures across the U.S. have been rising, due in part to rising global greenhouse gas emissions. In addition, much of the country has seen an increase in humidity. Together, these warmer, more humid environments are increasing the amount of mosquito friendly habitats.

These insects have a high mortality rate at temperatures outside the range of 50°F to 95°F or at relative humidity below 42 percent. So while a few parts of the country are becoming too hot to be favorable for mosquito habitats, for most of the U.S., the number of days with suitable conditions has risen. To understand future increases, the National Climate Assessment studied the Asian Tiger Mosquito, which can transmit West Nile and other diseases. For the Northeast, their projections suggest that the current 5 percent of suitable land for these mosquitoes will rise to 16 percent by 2035, possibly 49 percent by 2100.

Expansion of mosquito populations are a concern for health as well as comfort. With conditions becoming more conducive for mosquitoes, the chance of disease transmission goes up. After an unseasonably warm late spring, summer, and early winter in 2012, the U.S. experienced a West Nile Virus outbreak from the Asian Tiger Mosquito, resulting in the infection of over 5,600 people. The CDC suggests that this outbreak was connected to those higher temperatures, which may have led to larger mosquito populations. West Nile is only one of several mosquito-borne diseases that present an increasing threat to the U.S.; others include dengue fever and chikungunya.

And while many people think of malaria as a disease that doesn’t affect the U.S., travelers that have been infected abroad can pass the virus to local mosquitoes if bitten. In reality, malaria is not that distant. This month, the CDC has received multiple reports of malaria among U.S. travelers returning from the Dominican Republic, and Puerto Rican authorities have confirmed 14 cases of malaria, all from people returning from the Dominican Republic.