A US air marshal was attacked with a syringe at the airport in Lagos, Nigeria and had been hospitalised, the FBI said Monday.
It was not known what was in the syringe when it was injected Sunday into the on-duty marshal, whose name has not been given and is in hospital in Houston.
The incident raised fears the syringe could have carried some form of the Ebola virus because Nigeria is one of the African countries where the deadly epidemic has spread.
The FBI said authorities were taking every precaution, but that initial signs were that the victim was not a danger to others and was not showing any symptoms.
"Out of an abundance of caution, the Centers for Disease Control and Prevention conducted an on-scene screening of the victim when United Flight 143 landed in Houston early Monday morning," the statement said.
"The victim did not exhibit any signs of illness during the flight and was transported to a hospital upon landing for further testing. None of the testing conducted has indicated a danger to other passengers."
The incident came as the House announced that the US would devote more money tp fighting the Ebola outbreak.
President Barack Obama made the pledge in a telephone conversation Monday with UN Secretary-General Ban Ki-moon.
Obama has said previously that the deadly outbreak is a U.S. national security priority and that the American military will help set up isolation units and equipment in West Africa and provide security for public health workers.
Both leaders also agreed on the need for a broad coalition to counter the threat posed by the Islamic State group and to continue humanitarian assistance to civilians under threat in Iraq.
The White House said the leaders also discussed monitoring the cease-fire in eastern Ukraine and reviewed goals for the upcoming UN General Assembly.