The man placed in isolation Monday at Mount Sinai Hospital because it was suspected he might have the Ebola virus has tested negative for the virus, the hospital said late Wednesday.

"We would like to report that the Centers for Disease Control and Prevention have determined that the patient kept in isolation . . . has tested negative for Ebola Virus Disease (EVD). The patient is in stable condition, is improving, and remains in the care of our physicians and nurses," the hospital said in a statement.

It was not clear what disease he has or whether he remains in isolation.

The man, who had traveled recently to a West African country combating an Ebola virus outbreak, had been quarantined at the Manhattan hospital after he came to the emergency department early Monday with high fever and gastrointestinal symptoms.

From the beginning, hospital officials had emphasized that they were placing the man in isolation as a precaution. They stressed that it was more likely that the patient didn't have the Ebola virus and that people who had come into casual contact with him -- including those in the emergency department -- were not at risk of being infected.

New York City Health Commissioner Dr. Mary Bassett had said Tuesday that "looking at his history, we think it's highly unlikely that he has Ebola, but we're going to await the tests from the CDC."

So far no one has tested positive for the deadly and highly virulent virus in the United States. But the death toll from the virus in four West African countries continues to rise. As of Aug. 4, 932 have died, according to the World Health Organization.