Possible Long Island case of rare mosquito-borne chikungunya virus being investigated by New York State

The New York State Department of Health is investigating a possible case of a rare mosquito-borne virus locally transmitted to a person in Nassau County, officials confirmed Thursday.

Health officials said they have submitted samples to a state lab to confirm the case of chikungunya, a debilitating virus transmitted by mosquitoes that can cause joint pain and fever. If confirmed, it would be the first locally acquired case in state history, according to state health officials.

The New York Times reported the case was a 60-year-old woman who lives in the Town of Hempstead, who wanted to remain anonymous. Health officials would not give details about the person.

If the case is confirmed, state health officials said they will look at whether the person caught the virus locally or was infected abroad and then returned to the United States. The mosquito-borne illness is more commonly seen in tropical parts of South America, the Caribbean, Southeast Asia and Africa.

The name of the virus means "bends you up" or "stooped walk," according to the Mayo Clinic, due to its symptoms. Symptoms can appear two to seven days after a mosquito bite and can last for several weeks. They can linger for several months and while there is a vaccine against the virus, there is no treatment beyond supportive care, the clinic said. 

Nassau County has done routine mosquito testing and surveillance, and the virus has not been detected in mosquito pools, health officials said.

There were no cases of chikungunya reported in Suffolk this year, county health officials said.

State health officials issued a warning about the rarely fatal virus in August and have reported two upstate residents had confirmed cases of chikungunya after traveling abroad this year.

New York State last reported 26 cases in 2023, including two in Nassau. There were eight cases in 2022, including two in Suffolk and one in Nassau. All of the cases were transmitted from foreign travel.

"The risk to the public remains very low," state Health Department spokeswoman Danielle DeSouza said in a statement. "Routine mosquito testing has not detected chikungunya, and mosquito activity is already declining as the season ends."

If it is confirmed to be a locally transmitted case, it would be one of the first in the nation in several years, said Scott Weaver, director of the Global Virus Network Center of Excellence at the University of Texas Medical Branch and co-chair of the international chikungunya task force.

He said local transmission can occur when a person is likely first infected overseas and then may be bit by a local mosquito, which then carries the virus to another person. The last local transmission was a decade ago in Texas and Florida. 

The virus is not spread quickly, because it takes up to 10 days to incubate in an infected person, Weaver said.

"It should draw concern because it’s not often fatal, but it is very debilitating," Weaver said. "It's definitely a disease you don’t want to have."

Also, unlike mosquitoes carrying West Nile virus that tend to bite in early morning and evening, mosquitoes carrying chikungunya can bite all day, Weaver said. The mosquitoes can still transmit when temperatures are near the 80s, like on Long Island last week.

"It doesn’t mean huge outbreaks on Long Island or anyone else, but there are plenty of susceptible people to mosquitoes," Weaver said. "The risk to anyone on Long Island is very low, and people shouldn’t be panicking, but should still be protecting from mosquito bites."

Newsday's Lisa Colangelo contributed to this story

By John Asbury

john.asbury@newsday.comJohnAsbury

John Asbury is a breaking news and general assignment reporter. He has been with Newsday since 2014 and previously worked at The Press-Enterprise in Riverside, California.