Two patients are in isolation in U.S. hospitals while officials wait for test results to determine if they have been infected with the Ebola virus.

Officials believe that a woman in New Mexico and an unidentified patient in California are unlikely to have the deadly virus, but the two individuals are being isolated and tested out of an abundance of caution.

The New Mexico patient recently returned from Sierra Leone, where she worked as a teacher and began showing symptoms sometimes associated with the virus, including a fever, sore throat, body aches and headaches. Sierra Leone is one of four West African countries hit by the outbreak that has claimed more than 1,200 lives.

The 30-year-old patient is being treated in an isolation unit at the University of New Mexico Hospital; officials said she was in stable condition as of Monday.

"People who have to go to UNM Hospital, should keep their appointments and go there with full confidence that they will be safe," said New Mexico Department of Health Secretary Retta Ward in a statement.

A second patient in Sacramento, Calif., was admitted to the Kaiser Permanente South Sacramento Medical Center and is being treated in a negative pressure room by trained staff, the hospital said.

A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. (Reuters)

In a statement, the California Department of Public health called the case "low-risk" and said the person is being tested out of an abundance of caution according to guidelines established by the Centers for Disease Control and Prevention.

Blood samples from both patients are being sent to the CDC to rule out the presence of Ebola.

Other than two Ebola patients who were flown from West Africa to Atlanta, Ga., for treatment, there have been no confirmed cases of Ebola in the United States.

People infected with Ebola are only contagious once symptoms begin to appear, which can take as long as 21 days. Ebola is contracted through direct contact with the bodily fluids of an infected person, and the World Health Organization has said that unlike other infectious diseases -- such as the flu-- Ebola is not transmitted through the air. There is little risk of infection through air travel.

As the worst Ebola outbreak in history unfolds in West Africa, The Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)