A group of 13 passengers were taken to hospital after arriving in Boston on an American Airlines flight from Miami.
In all, 16 students and their chaperones traveling together complained of illness, according to Boston Emergency Medical Services.
Massachusetts Port Authority spokeswoman Samantha Decker said symptoms indicated a non-serious condition and the airline said no other passengers or crew members complained of feeling ill.
American suggested the cause was likely food poisoning.
All members of the group had eaten together in Ecuador the night before returning to the US, and began falling ill on the journey home.
The 16 were part of a larger group of about 40 people, American said.
"No other passengers were ill. American requested paramedics to meet the aircraft upon arrival in Boston," the carrier said.
Of the 13 hospitalised, several were treated and released after a few hours.
All were aged 15-17 years old, Boston Emergency Medical Services said.
