Yale Climate Connections West Nile sickened hundreds in the most affluent residential area in Dallas in 2012. Chicago, Los Angeles, and Sacramento suffer from hot spots, too. What’s helping it thrive in cities? Each summer, as mosquitoes begin to buzz, the risk of West Nile virus quietly rises — and cities aren’t immune.
In 2012, it burned through the Park Cities, two wealthy municipalities surrounded by the city of Dallas, causing 225 cases of West Nile fever, 173 cases of the more serious neuroinvasive form of the disease, and 19 deaths.
In the U.S., the West Nile virus is most frequently spread by Culex mosquito species, such as Culex pipiens and Culex quinquefasciatus. About 80% percent of people infected with West Nile virus don’t develop any symptoms. But about one in five will develop a fever with flu-like symptoms, and about one in 150 people will develop a severe neurological illness such as encephalitis or meningitis, which can lead to paralysis and death.
Although many people may think of mosquito-borne illnesses as a concern in tropical regions or rural landscapes, cases of West Nile virus have been identified in every state in the U.S., with the highest infection rates in the Great Plains states. And major cities like Los Angeles, Chicago, and Dallas-Fort Worth see the most total cases, according to the National Oceanic and Atmospheric Administration.