Global warming may be bad news for us, but it’s good news for disease-carrying mice, rats and insects. Warm-weather insects like ticks and mosquitoes used to be restricted to tropical areas and were killed off in the winter, but they’re now living longer and migrating farther north. As these insects spread, they’re exposing large populations of people to diseases they’re unprepared to combat.
Dengue fever, a disease that causes internal bleeding and has no vaccine, has spread to Florida. Ticks carrying Lyme disease have spread to the coastlines of Scandinavia, an area that was previously too cold for them to survive. Cholera appeared in the newly warmed waters of South America for the first time in 1991. And West Nile virus, once confined to countries along the equator, is now found as far north as Canada and has infected more than 21,000 people in the United States.