[This post has been updated multiple times.]

A man who was tested for Ebola at New York’s Mount Sinai Hospital on Monday is “unlikely” to have the virus, the city’s health department said.

“After consultation with CDC and Mount Sinai, the Health Department has concluded that the patient is unlikely to have Ebola,” the New York City Department of Health and Mental Hygiene said in a statement early Monday evening. “Specimens are being tested for common causes of illness and to definitively exclude Ebola.”

The specimen was delivered to the Centers for Disease Control and Prevention in Atlanta, with test results expected within 24 to 48 hours, the hospital said in a statement Tuesday afternoon.

The male patient had come to the hospital’s emergency room early Monday morning with a high fever and gastrointestinal problems, according to the hospital. The man had recently visited a West African country where Ebola has been reported; he was “placed in strict isolation” and screened for the virus.

“The patient, who remains in isolation, was stable overnight and in good spirits,” the hospital said in its Tuesday statement. “No other patients have presented with similar symptoms and travel history to West Africa. We will continue to work closely with federal, state and city health officials to address and monitor this case, keep the community informed and provide the best quality care to all of our patients.”

Mount Sinai also knocked down a news report that a second person was being tested for Ebola at the Manhattan hospital. “Contrary to a recent report in the New York Post, there is only one patient currently at Mount Sinai being tested for the Ebola Virus Disease,” the hospital said in its statement.

Two Americans with Ebola have been transported to the United States from West Africa for treatment; the second patient — Nancy Writebol, a missionary from Charlotte, N.C. — arrived in Atlanta on Tuesday. Both Writebol and American doctor Kent Brantly are being treated at Emory University Hospital. The two patients have also received an experimental serum.

Hospitals in New York have been on high alert, said Ian Michaels, New York City Health and Hospitals Corp. spokesman.

Last week, Michaels said, a man returning from a West African country where Ebola has been reported was detained at John F. Kennedy International Airport for a minor law enforcement issue. During his detainment, the man got a sudden headache and fever and was taken to Bellevue Hospital, where he was placed in isolation for consideration of Ebola, Michaels said. But within 24 hours, the man improved and was released.

Mount Sinai is not part of the New York City Health and Hospitals Corporation system.

The worst Ebola outbreak in history continues to devastate West Africa — in particular, Liberia, Guinea and Sierra Leone. The World Health Organization has reported 887 deaths as of Aug. 1 and a total of 1,603 recorded cases. On Monday, Nigerian health officials announced a second case of Ebola in Lagos, the largest city in Africa.

The World Health Organization calls Ebola “one of the world’s most virulent diseases.”

Ebola is spread through direct contact with the blood or secretions of an infected person, or through exposure to objects such as needles that have been contaminated with such bodily fluids, according to the Centers for Disease Control and Prevention.

It can take up to 21 days for Ebola symptoms to show. Someone infected with the disease isn’t considered contagious until the symptoms surface, according to the World Health Organization.

Last week, the CDC issued a Level 3 alert in response to the outbreak, warning against all non-essential travel to Guinea, Sierra Leone and Liberia, where the outbreak is concentrated.