A Liberian passenger who flew into New Jersey on Tuesday was taken to hospital over fears he had been exposed to Ebola, media reported.
The man, who had flown from Liberia to Brussels and then caught a connecting flight to Newark, had a fever, NBC New York reported, citing unnamed officials.
The passenger was "identified as reporting symptoms or having a potential exposure to Ebola," a spokeswoman for the US Centers for Disease Control and Prevention (CDC) told the network. The CDC was not immediately available for comment.
Liberia, Sierra Leone and Guinea are at the epicentre of the world's worst reported epidemic of the hemorrhagic fever that has killed more than 4,500 people.
Three Ebola cases have been confirmed in the United States: Liberian Thomas Eric Duncan, who died on Oct. 8 at Texas Health Presbyterian Hospital in Dallas, and two nurses who treated him.
The United States ratcheted up its safeguards against Ebola on Tuesday, requiring travellers from the three West African countries to fly into one of five major airports conducting enhanced screening for the virus.