What to know about measles on Long Island after child in Nassau tests positive

Measles cases in the United States are at their highest point in 20 years. Vaccination rates are dropping. And some experts believe the country’s hard-won measles elimination status, earned in 2000, is slipping away.

Cases on Long Island are still relatively rare but the news that an unvaccinated child under the age of 5 in Nassau County tested positive for the contagious viral illness has prompted public health officials to warn people about the danger of measles and the importance of vaccination.

In a statement, Nassau County Health Commissioner Dr. Irina Gelman reminded people that measles can "cause serious illness, with complications that may include pneumonia, encephalitis, and often results in hospitalization and sometimes death."

Here is what you need to know about measles on Long Island.

What do we know about the measles case in Nassau County?

Health officials said the child is under age 5 and not vaccinated. They had not attended daycare or school, but anyone who was in contact with the child is being identified and checked for possible exposure.

Citing privacy issues, officials wouldn’t say whether the child had traveled or been exposed to someone who traveled recently.

The Centers for Disease Control and Prevention said measles cases in the United States "often originate from unvaccinated international travelers" noting the disease is common in parts of Europe, the Middle East, Asia and Africa. But more local transmission is happening in states where there have been outbreaks such as South Carolina, Utah, Texas, Arizona and Florida.

What are the symptoms?

Symptoms include a rash, high fever, cough, runny nose and red, watery eyes. They usually appear about one or two weeks after being in contact with the virus.

"Measles spreads through airborne transmission, meaning an infected person spreads the virus by exhaling tiny particles that are then inhaled by a non-immune person," Dr. Andrew Handel, a pediatric infectious disease expert at Stony Brook Children’s Hospital, told Newsday in an email.

"These particles may remain in the air for up to 2 hours, resulting in transmission long after the infected person leaves an enclosed space," he said. "People with measles are typically diagnosed once they develop a distinct rash, but are actually contagious for four days before the rash begins. As a result, measles is among the most contagious infections that exist."

How common are measles cases on Long Island?

The current Nassau case is the only one in 2026 on Long Island. In 2025, Suffolk County reported a young, unvaccinated child had tested positive for measles. Nassau reported one case, also in a young, unvaccinated child, in 2024. Before that, the last cases on Long Island came in 2019 with three in Nassau and one in Suffolk.

Nationally, there were 2,288 measles cases in 2025 and 1,814 so far in 2026. Other than the 1,274 in 2019, the number of cases had not exceeded 1,000 since 1992.

"The epicenter keeps shifting," said Dr. Sunil Sood, director of pediatric infectious diseases at Cohen Children’s Medical Center. "It started with a huge outbreak in West Texas, followed by the very recent one in South Carolina and the latest in Utah. Sporadic cases continue to happen all around the country including in the tristate area."

How can I protect myself?

Get vaccinated, Sood said. The CDC recommends children receive their first dose of the measles, mumps and rubella vaccine (MMR) between 12 and 15 months and the second dose between 4 and 6.

State health department data shows 82.2% of children in Suffolk County and 82.3% in Nassau have received one dose of MMR by age 2. Between 92% and 94% of the population needs to be immune through vaccination or previous measles infection to limit the spread of measles in the community, according to the American Academy of Pediatrics.

Children younger than 12 months may be able to receive the vaccine earlier if they are traveling or in the midst of a community outbreak.

I thought the MMR was mandatory for children?

"A growing portion of families are refusing the vaccine until their child is old enough to attend school and therefore required to receive it, or are home-schooled and avoid MMR vaccine entirely," Handel said. "Also, many individuals have medical problems that prevent them from getting the vaccine, such as having an immunodeficiency or cancer."

Do parents really need to worry?

Sood, whose career includes time in the United States and abroad over several decades, said he had "seen everything that measles can do" including cause death.

"Measles can cause a really severe pneumonia, damage to the immune system for a long period of time, activate a latent tuberculosis that you could be harboring without knowing it," he said.

Some children may develop subacute sclerosing panencephalitis (SSPE) after a measles infection. It can lead to mental and physical deterioration and death.

"I am one of only two people I know around me who have seen it because I worked in India," Sood said. "This should be very, very scary to any parent."

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.