Kids from all over the world attend the EF International Language School to get a better education, never dreaming they might also get sick.
There's concern anyone who attended a social gathering inside Rita Hall on Friday may have been exposed to the Measles.
Officials from the Westchester County Department of Health declined to go on camera, but experts at Westchester Medical Center did talk with Eyewitness News about the virus.
"It's very contagious spread from person to person through the air, coughing and sneezing, if you are in the same room can breath in the droplets," said Dr. Jose Munoz, who specializes in Pediatric Infectious Diseases at the Westchester Medical Center.
About 200 high school students from abroad were at the school event.
A chaperon later tested positive for the measles and was hospitalized, but has recovered.
Now officials are retracing that person's steps.
The male adult checked in the Westchester Marriott Friday evening, checked out the next day.
More than 900 other guests were staying there at the same time.
Symptoms usually occur in 2 stages, first a runny nose, cough, slight fever, your eyes may become red and sensitive to light.
During phase two, your fever will rise; you'll get a red blotchy rash and white spots inside your mouth.
Officials say it's rare they only see about 100 cases of the measles each year in the US.
"We see very few cases because we live in a highly immunized society, the key is immunization," Dr. Munoz said.
There are two other locations officials are concerned about, Ruth's Chris Steak House and Eva's Hair Salon.
Both are located inside the Marriott.
Although the infected person did not go into either business, both share the same ventilation system with the hotel.
Experts say if you've been exposed to the Measles the best thing to do is call your doctor.