Increase in West Nile Virus Cases Reported in NYC

Nearly 20 people in New York City have been diagnosed with West Nile Virus this year, based on data from the city’s health department.

The 23 confirmed cases are spread across various boroughs: three in the Bronx, seven in Brooklyn, two in Manhattan, three in Queens, and another three on Staten Island.

This number exceeds the 18 cases confirmed throughout all of 2025, although that year had lower figures compared to previous years. For reference, there were 36 cases in 2024, 32 in 2023, and 46 in 2022.

The virus is mainly transmitted via bites from infected mosquitoes and is not contagious from person to person. Symptoms can range from mild to severe. Most individuals who contract the virus don’t show any symptoms. Some may experience mild flu-like effects, such as fever and body aches, while others might develop more serious complications involving the central nervous system, leading to muscle weakness and brain swelling, according to officials.

Out of 23 confirmed cases in the city, 18 are classified as having West Nile neuroinvasive disease, which is a more serious form of the illness. The remaining five cases were categorized as West Nile fever without central nervous system involvement.

Sally Slavinski, the director of the city’s health department’s Zoonotic and Vector-Borne Disease Unit, explained that the higher number of neuroinvasive cases suggests that many infected individuals do not get sick enough to seek medical attention. “Young, healthy individuals may not realize they’re infected or may only experience mild illness. These are not necessarily the people who get tested,” she noted. “The ones who do get tested are typically the ones who are severely ill and require hospitalization.”

The health department estimates that one in 150 people who contract the virus will experience severe illness, implying that for every serious case recorded, there could be up to 149 others who are asymptomatic or experience mild symptoms.

In addition to tracking human cases, city health officials are also testing for the virus in mosquito populations throughout the boroughs. This year, over 1,600 mosquito pools have tested positive for West Nile Virus, marking a record high, as mentioned by Slavinski. She attributes this increase partly to climate change, which allows mosquitoes to thrive in warmer and longer summers, thereby boosting transmission rates.

“Warmer temperatures can accelerate the mosquito life cycle and enhance viral replication,” she remarked. “This leads to a quicker transition from an infected mosquito to transmission. Moreover, increased rainfall and humidity support mosquito populations, which, combined with longer warm seasons, creates more opportunities for the virus to spread.”

Slavinski urged New Yorkers to be cognizant of the risks associated with West Nile Virus, particularly for those aged 65 and older, who are three times more likely to develop neurological illnesses compared to younger individuals. People with chronic health issues like cancer, diabetes, hypertension, or kidney disease, as well as those with compromised immune systems, are also at greater risk.

To minimize exposure to mosquito bites, health officials recommend that New Yorkers limit outdoor activities during dawn and dusk when mosquitoes are most active, use EPA-approved insect repellents that contain DEET, picaridin, IR3535, or oil of lemon eucalyptus, and dress in long-sleeved clothing and pants. Additionally, it’s important to eliminate standing water in places like buckets and flower pots at least weekly, and to maintain cleanliness and coverage for swimming pools, hot tubs, and ponds when not in use, as per the health department’s guidance.