West Nile Virus Detected in New Yorkers for the First Time This Year
West Nile virus has been detected in mosquitoes in all five boroughs; four people with West Nile virus disease have been reported
The Health Department is treating parts of the city with mosquito activity; there have been 10 completed adulticiding spray operations, three aerial larvicidings, two rounds of catch basin larviciding and 1,634 ground-based larvicidings to date
August 19, 2024 — The Health Department today announced that West Nile virus disease has been reported in four people living in New York City and the virus has been detected in mosquito pools across all five boroughs. Mosquitoes infected with West Nile virus are typically present in New York City from May through October, with peak activity during August and September. Infected mosquitoes can spread West Nile Virus to people through a bite. The four people with West Nile virus disease reside in Queens and Manhattan; one was diagnosed with West Nile fever and three were hospitalized with neuroinvasive disease, beginning in late July. In addition, the virus was detected in blood donations from three people who reside in Brooklyn, Queens and Manhattan. Reports of two people with possible West Nile virus disease from the Bronx are also under investigation.
“The Health Department is actively working to prevent West Nile through public education, treating marshy areas and spraying for mosquitoes,” said Health Commissioner Dr. Ashwin Vasan. “We all have a role to play to protect ourselves and each other. Using an EPA-registered insect repellent is one very important tool, especially when outside at dusk and dawn, when the types of mosquitoes that transmit West Nile virus are most active. You can also stop mosquitoes from laying eggs and reproducing in the water by emptying outdoor containers that hold water or calling 311 if you see standing water that you cannot empty.”
The Health Department routinely traps and tests mosquitoes from across New York City. Once trapped, up to 50 mosquitoes are batched together and tested as a single pooled sample or “pool.” As of Friday, August 16, there have been a total of 1,286 positive mosquito pools across the five boroughs, far exceeding the 569 positive pools detected at this time last year.
Most people infected with West Nile virus have no symptoms though some may develop fever, headache, muscle aches, rash and extreme fatigue. While the majority of patients infected with West Nile virus disease go on to fully recover from their illness, some continue to have problems months after infection. In addition, some people (about 1 in 150), especially those 60 years and older or with a weakened immune system, can develop a serious and potentially fatal illness of the brain and spinal cord called West Nile neuroinvasive disease, leading to changes in mental status and muscle weakness requiring hospitalization. New Yorkers, especially those at risk for West Nile neuroinvasive disease, should use an EPA registered mosquito repellent when outdoors to prevent mosquito bites. People with certain medical conditions or treatments that cause severe immunosuppression, such as chemotherapy and organ transplantation, are at greater risk of West Nile neuroinvasive disease and should consider avoiding going outdoors during dusk and dawn when mosquitoes that carry West Nile virus are active and bite. If a person has symptoms of West Nile virus, they should contact their health care provider.
West Nile virus was first detected in New York more than 20 years ago. Over the past decade, an average of 17 people have been diagnosed with West Nile neuroinvasive disease per year in New York City; their median age was 62 years (ages ranging from 22 to 95 years) and the case fatality rate was 10 percent (18 deaths).
New York City has more than 40 species of mosquitoes, but West Nile virus is transmitted primarily by several Culex species, including Culex pipiens and Culex salinarius.
Reducing Exposure to Mosquitoes
- Use an approved insect repellent containing picaridin, DEET, oil of lemon eucalyptus (not for children under three), or products that contain the active ingredient IR3535. Visit the EPA site to search by product and duration of effectiveness.
- People with severely compromised immune systems should avoid going outdoors during dusk and dawn when mosquitoes that carry West Nile virus are active and bite.
- Make sure windows have screens. Repair or replace screens that have tears or holes.
- Eliminate any standing water from your property and dispose of containers that can collect water. Standing water is a violation of the New York City Health Code.
- Make sure roof gutters are clean and drained properly.
- Clean and chlorinate swimming pools, outdoor saunas and hot tubs. Keep them empty or covered if not in use. Drain water that collects in pool covers.
For more information about West Nile virus or to report standing water, visit NYC Health: West Nile Virus or call 311.
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MEDIA CONTACT: Patrick Gallahue / Shari Logan
PressOffice@health.nyc.gov