Those at high risk include pregnant women and infants under age 1 who may have come in contact with the 8-month-old boy, who arrived at Newark-Liberty Airport from Israel on April 2.
The baby, who was not identified, is doing well, health officials said.
Officials in Nassau County said Monday they learned the baby apparently had been at the Fortunoff Source Mall in Westbury, as well as in several stores in Cedarhurst, last Thursday between 1 p.m. and midnight, and may have exposed thousands to the disease.
On Tuesday, health officials in neighboring Suffolk County on eastern Long Island issued a similar advisory for any of its residents who may have come in contact with the boy.
Measles can be spread by coughing, sneezing and through the air, meaning anyone in a room with someone infected can potentially get the disease. It can result in severe complications, including encephalitis, pneumonia, and death. Because the symptoms are so debilitating, those sickened often go to hospital emergency rooms or clinics, where they can infect large numbers of people.
Also Tuesday, New York City health officials advised residents traveling abroad, especially to Europe and to Israel, to make sure they are vaccinated against measles.
"Vaccinations are the safest and most effective way to protect yourself and others, whether you are traveling to Europe or to a developing country," said Dr. Jane R. Zucker, the Health Department's assistant commissioner for immunization.
Ten measles cases have been identified so far in the city in 2008. Last year, the city Health Department investigated 36 suspected measles cases, and five were confirmed.
According to the Centers for Disease Control and Prevention's National Center for Immunization and Respiratory Diseases, 24 measles cases have been reported nationwide this year.
The Nassau County Department of Health will be providing vaccine to those high risk individuals who have been exposed. This will be provided at the Health Department building, 106 Charles Lindbergh Blvd., Uniondale, South entrance to the building, between 5:30 and 8:30 p.m..tonight, April 7 through April 9.
Individuals should call the888-844-8657 number to register and get directions.
