Matthew Hersh

Large numbers of dead or dying geese began turning up at parks around the state last month, prompting renewed concerns from local health officials and state wildlife biologists about the extent of a possible avian flu outbreak.

More than 1,100 dead or sick wild birds were reported to the state Department of Environmental Protection (DEP) between February 14 and 16, the weekend when reports began to spike. The New Jersey Department of Environmental Protection Fish & Wildlife and the U.S. Department of Agriculture are tracking incidences of suspected bird flu cases in wildlife around the state.

“Locally, we continue to monitor state notifications closely,” said Princeton Health Officer Jeffrey Grosser. The Princeton Health Department is notified by state agencies if local detections occur along with updates on any specimens the town submits to the state for testing.

Highly Pathogenic Avian Influenza (HPAI), or “bird flu,” is a respiratory disease of birds caused by influenza A viruses, according to DEP. Wild birds, such as ducks, gulls, and shorebirds, can carry and spread these viruses but may show no signs of illness. However, avian influenza can kill domestic poultry, such as chickens, turkeys, ducks, and geese.

Grosser said there are no documented cases of person-to-person spread in the U.S., and most human infections nationally have been mild and linked to direct unprotected exposure to infected animals. While local officials have indicated no widespread outbreak of bird flu cases in Mercer County, outbreaks have been documented in surrounding counties, including Monmouth, Burlington, and Somerset.

This season, there have been confirmed cases among wild birds, domestic poultry, domestic cats, and black bears, Grosser said. The virus has been present in wild bird populations in the region since 2022, with periodic increases in detections corresponding to seasonal migration patterns, particularly during fall and winter months when waterfowl movement increases. If a confirmed positive animal detection occurs in the area, Grosser said the state and Princeton Department of Health collaborate to avoid potential human exposure risks and conduct monitoring if necessary.

Between 2024 and 2025 there has been increased national attention due to detections in dairy cattle and sporadic human cases in other states, most of which were associated with occupational exposure. Locally, Grosser said H5N1 flu is currently widespread in wild birds globally and continues to cause outbreaks in poultry and dairy cattle in the U.S. At the municipal level, Princeton works in coordination with DEP. For smaller bird flu outbreaks, the municipality typically proceeds with disposal using strict biosecurity protocols, including personal protective equipment and proper disinfection procedures.

Human H5N1 infections are rare and typically occur after prolonged, direct, unprotected contact with infected animals or contaminated environments, Grosser said.

“The average resident going about daily activities, including walking in parks or spending time outdoors, is at low risk,” he said. Grosser and the Princeton Health Department are advising residents to avoid direct contact with sick or dead birds; keep pets, especially cats, indoors to prevent exposure; avoid feeding pets raw milk or raw meat; and practice good hand hygiene after outdoor activities.

Grosser said residents should avoid contact with any dead birds and to report it to the DEP at dep.nj.gov/njfw/highly-pathogenic-avian-influenza. If residents do handle dead birds, Grosser said not to touch it with bare hands, avoid exposure to children and pets, and to wash hands thoroughly after contact.