A Dallas hospital expects preliminary test results Tuesday that may confirm whether a patient there has Ebola.

Texas Health Presbyterian Hospital of Dallas placed the patient into "strict isolation" after the person's symptoms and recent travel history raised concerns, spokeswoman Candace White said in a written statement Monday.

The name and other details about the patient were not released.

The hospital said it is following Centers for Disease Control and Prevention recommendations to ensure the safety of patients, staff members and visitors.

No Ebola cases have been confirmed in the United States, though several aid workers who contracted the disease in West Africa have returned to the U.S. for treatment.

Last month, patients in Sacramento and New York City were isolated because of concerns they'd contracted the disease, but they tested negative for the virus.

Specimens from such patients are delivered to the CDC in Atlanta for testing that takes 24 to 48 hours.

There have been more than 6,500 cases of the disease in Africa and more than 3,000 deaths have been linked to it, according to the World Health Organization. Liberia, Sierra Leone and Guinea have been hit the hardest.

Ebola has killed up to 90 percent of those it has infected, but the death rate in this outbreak is closer to 60 percent because of early treatment.

The virus spreads through direct contact with blood, organs or other bodily fluids and with surfaces contaminated with the fluids.

Early signs of Ebola such as fever, diarrhea and vomiting can develop within two days of infection.

There is no specific treatment for Ebola, but doctors can provide fluids and pain relief before symptoms become severe. Death occurs from profuse internal and external bleeding that starves the organs of blood.

Dr. Kent Brantly, a Fort Worth physician who contracted the virus in July while doing relief work in Africa, was treated in an Atlanta hospital. He was discharged in August after nearly three weeks of treatment.

He and another American aid worker, Nancy Writebol, received an experimental treatment called ZMapp. It's unknown whether the drug helped or whether they improved on their own.

On Sunday, an American doctor who was exposed to the Ebola virus while volunteering in Sierra Leone was admitted to an isolation unit at a hospital at the National Institutes of Health near Washington D.C.

Another aid worker who contracted Ebola while volunteering in West Africa also remains hospitalized.

The World Health Organization was first notified of the latest Ebola outbreak in March, but investigations have revealed that it began in December 2013.

Outbreaks have occurred in Central Africa since the 1970s, but this is the first in West Africa and the largest outbreak in history.

Staff writers Claire Z. Cardona and Sherry Jacobson and The Associated Press contributed to this report.