(AP) A man who recently visited West Africa and had a high fever and gastrointestinal symptoms was placed in isolation at a New York hospital on Monday and was being tested for possible Ebola but likely didn't have it, health officials said.



"Odds are, this is not Ebola," said Dr. Jeremy Boal, chief medical officer at Mount Sinai Health System in Manhattan.



Boal said he expected a definitive answer about the man's condition within a day or two.



The man, who recently traveled to a country where Ebola has been reported, was ill when he arrived at Mount Sinai Medical Center early Monday.



The city's Department of Health echoed what Mount Sinai hospital officials said, that "the patient is unlikely to have Ebola." It said more testing was being done for common causes of illness and to definitively exclude Ebola.



The Centers for Disease Control and Prevention has said three Americans in the United States were tested for Ebola since the West African outbreak erupted this year and those results were negative.



Officials at U.S. airports are watching travelers from Africa for flu-like symptoms that could be tied to the recent Ebola outbreak there.



The Ebola virus causes a hemorrhagic fever that has sickened more than 1,600 people, killing nearly 900 mostly in Liberia, Guinea and Sierra Leone. It's spread through direct contact with bodily fluids. A person exposed to the virus can take up to 21 days to exhibit symptoms, making it possible for infected travelers to enter the U.S. without knowing they have it.



Over the weekend, an American physician infected with Ebola was brought to the United States from Africa. He was being treated in Atlanta. A second American aid worker diagnosed in West Africa arrived in the Atlanta area Tuesday for treatment.

Health officials say the threat to Americans at home remains relatively small. But border patrol agents at airports in New York and Washington have been told to ask travelers about possible exposure to the virus and to be on the lookout for anyone with a fever, a headache, achiness, a sore throat, diarrhea, vomiting, stomach pain, a rash or red eyes.



While the CDC says it is not screening passengers boarding planes at African airports - the job of local authorities there - it said it has encouraged vulnerable countries to follow certain precautions. Outbound passengers in the countries experiencing Ebola are being screened for fevers and with health questionnaires.