This year, as many as 40,000 Americans have been infected with the virus, and hundreds of others have died.
The Centers for Disease Control and Prevention has officially tallied 50,000 cases of West Nile virus in the United States so far this year. According to the agency, 49,499 people have been infected; 20,467 of them have been hospitalized.
But the CDC’s estimates are likely an underestimate, as the agency never counts cases from public health emergency declarations. A number of states, including Florida, Texas, New York, and New Jersey, have declared the virus a public health emergency this year. In New York, the number of West Nile cases has rocketed to 1,800 so far this year.
Why it’s spreading
This year’s West Nile outbreak is partly caused by the mosquito that spreads the virus: Aedes aegypti. Its usual territory is part of the eastern United States, but the West Nile virus has been successfully transmitted to Dallas, Texas, and Missouri this year. New Jersey is still on the list of states without an active case.
Other factors: The current weather patterns, warm temperatures, and a combination of factors, including air conditioning, that allow the mosquito to survive outside all summer long.
Are there any vaccines or medications?
The CDC already recommends that people limit their exposure to mosquitoes and wear clothing that covers as much skin as possible.
Plenty of drugs and vaccines have been created to treat and prevent other viruses, like Zika, dengue and Dengue-Shigella. But researchers have yet to develop a vaccine or medicine that can help protect people from all of the variety of viruses that can be spread by mosquitos.