Chikungunya virus case confirmed in Nassau resident is first ever locally-acquired case in NY state, health officials say
A Nassau County resident has tested positive for chikungunya, marking the first locally acquired case of the rarely fatal mosquito-borne illness in New York State, health officials announced Tuesday.
While the transmission occurred within the state, the exact source of the infection remains unknown, the New York State Department of Health said in a news release Tuesday.
Three additional cases of the illness, all linked to foreign travel, have been found in New York this year, state health officials said. The state last reported 26 cases of chikungunya, including infections of two Nassau residents, in 2023. Those infections occurred during travel outside the country.
Transmission of the virus in the continental United States was unheard of until occurrences in both Florida and Texas in 2014, according to the Centers for Decease Control and Prevention. Tuesday’s announcement marked the first locally acquired case of chikungunya in the United States and its territories since 2019, the state said.
Local and state health officials said the risk of further transmission this late in mosquito season remains low.
“Given the much colder nighttime temperatures, the current risk in New York is very low,” state Health Commissioner Dr. James McDonald said in a statement.
The state health department investigation “suggests that the individual likely contracted the virus following a bite from an infected mosquito,” such as the Aedes albopictus mosquito, which is present in New York and is known to transmit chikungunya, the release reads.
Local transmission of the virus, which causes fever and joint pain, can occur when a local mosquito bites an infected traveler who returned with the infection from overseas. That insect then becomes infected and transmits the virus to another human via bite, the department said.
The infected individual “had history of traveling outside of Nassau County during the period of inoculation, but did not report traveling abroad,” reads a Nassau County Department of Health news release issued Tuesday. The individual — whom county and state health officials did not identify — began experiencing symptoms of the virus in August.
Weekly testing of mosquitoes acquired from dozens of traps throughout the county did not reveal the chikungunya virus, the county health department said. Similar statewide testing had the same results,the state health department said.
“There is no evidence of ongoing transmission of the virus and the risk to the general public remains low,” the Nassau Health Department release reads.
Last month, the New York State Department of Health launched an investigation to determine whether a Nassau County resident who tested positive for the debilitating virus in a preliminary screening was infected within the county, Newsday reported. It was unclear whether that resident is the same one whose case was confirmed Tuesday.
In humans, the virus “can be severe and disabling,” the Nassau County health department release reads. While most infected individuals recover within a week, newborns, senior citizens and people with chronic conditions are at a higher risk for a severe infection, according to the state health department.
The virus’ name, which translates to “bends you up” or “stooped walk,” is derived from its symptoms of severe joint pain, according to the Mayo Clinic. The mosquitoes which carry the infection and human cases are more commonly seen in the tropical areas of Africa, the Caribbean, South America and Southeast Asia.
Mosquitoes found on Long Island have transmitted other viruses, most notably West Nile virus, to humans. While these human infections are rare, they “can cause serious health complications in vulnerable populations,” the Nassau Health Department said. Health experts previously told Newsday chikungunya is a less lethal and less serious infection compared with West Nile.
Nassau County residents are advised to cover their skin with long clothing or use EPA-approved bug repellent on exposed skin if they are outdoors where mosquitoes remain present, health officials said. Stagnant water pools should be eliminated.
“Mosquito bites are more than just a nuisance, they can sometimes spread illnesses that affect both people and animals,” Nassau County Commissioner of Health Dr. Irina Gelman said in a statement Tuesday. “While the 2025 mosquito season is essentially over with cooler weather in Nassau County, this case serves as a reminder to take precautions against mosquito bites during the season and when traveling to areas where mosquito-borne illnesses are present.”
Nicholas Grasso covers breaking news for Newsday. A Long Island native, he previously worked at several community newspapers and lifestyle magazines based on the East End.
