New York confirms first locally acquired Chikungunya case in US since 2019

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By Mrinalika Roy

(Reuters) -The New York State Department of Health has confirmed a locally acquired case of Chikungunya on Long Island, the first such case of the mosquito-borne infection reported in the United States since 2019.

Laboratory testing at the department’s Wadsworth Center confirmed the case in Nassau County, the agency said in a statement released on Tuesday.

While the infection is classified as “locally acquired” based on current information, health officials said the exact source of exposure remains unclear.

Chikungunya is a viral disease that causes fever, intense joint pain, headache, muscle aches, rashes, nausea, and fatigue, per the World Health Organization.

An HHS spokesman declined to comment on the case and referred back to the New York health department’s release.

So far in 2025, Chikungunya has remained largely an imported disease in the U.S., with 88 travel-associated cases reported among residents as of September 30, according to the Centers for Disease Control and Prevention.

“The case is interesting because the source of exposure for this individual is unclear,” said Dr Amesh Adalja, an infectious disease expert and senior scholar at the Johns Hopkins University Center for Health Security.

“My understanding is that pools of mosquitoes in the patient’s area have not tested positive. However, it could be that specific pools that are not part of the sample harbor the virus.”

He said that the types of mosquitoes that carry the virus do exist in the area, “so all it takes is an infected traveler to seed local mosquitoes, as has happened in Florida and Texas in years prior.”

Newborns, seniors over 65, and people with chronic illnesses face higher risk of severe symptoms, the New York Health Department said.

Officials urged residents to take precautions against mosquito bites, but stressed that the risk of infection in New York is very low given the cooler fall temperatures.

(Reporting by Mrinalika Roy in Bengaluru and Julie Steenhuysen in Chicago; Editing by Shinjini Ganguli)