NORTHERN, N.J. — New Jersey health officials are alerting residents after measles virus was detected in a wastewater sample in northern New Jersey, though no confirmed cases have been identified.
The state Department of Health said the virus was found in a sample collected March 20 from an Essex County treatment plant that serves parts of Bergen, Passaic, Hudson, Union and Essex counties. A follow-up sample taken March 23 tested negative.
Officials said wastewater surveillance can act as an early warning system and that a single detection does not indicate an outbreak. No clinical cases have been reported in the region, and the last confirmed measles case in a New Jersey resident was recorded in October 2025.
Health officials said the test detected wild-type measles virus, meaning it did not come from a vaccine strain and may indicate that someone with a recent or current infection was present in the area. That individual could have been a resident, worker or traveler passing through, including via Newark Liberty International Airport.
The virus spreads through the air and close contact with an infected person but is not known to spread through wastewater.
The detection was reported by WastewaterSCAN, a national monitoring program. Additional testing is planned by both state and private laboratories.
Officials are urging residents to ensure they are up to date on the measles, mumps and rubella vaccine, particularly as travel and large gatherings increase during the spring and summer months.
Health officials also advised anyone experiencing symptoms such as high fever, cough, runny nose, red eyes or rash to contact a health care provider or local health department before seeking in-person care to prevent potential spread.
