Another patient has been transferred to Emory University Hospital in Atlanta for treatment of Ebola, as confirmed by CNN News.

It has been less than a month since the first two American patients to contract the disease, Dr. Kent Brantley and Nancy Writebol, were discharged from Emory University Hospital. Yet, American patients who carry the deadly virus continue to be transferred to isolation units and medical centers in the United States.

A male U.S. citizen arrived at Emory University Hospital from West Africa on Sept. 9to begin treatment, according to CNN. This will be the fourth Ebola patient to receive treatment in the U.S.

According to the Los Angeles Times, another American doctor, Dr. Rick Sacra, arrived in the United States on Sept. 5 from Liberia after testing positive for Ebola. He is currently under treatment at Nebraska Medical Center in Omaha.

Three out of the four American citizens with the disease  tested positive while working in West African Ebola treatment centers. CNN reports Sacra was delivering babies in Liberia when he contracted the disease.

The outbreak has mainly affected regions in Western Africa, including Liberia, Guinea and Sierra Leone. Other reports have popped up in Nigeria and Senegal as well. Most cases are a result of contact with bodily fluids from those infected with the virus.

According to the World Health Organization, more than 4,200 cases of Ebola have been reported since December, and over 2,000 of those cases have resulted in fatalities. Symptoms of Ebola usually appear anywhere within two to 21 days, and include a high fever of 101.5°F or above, muscle pain, severe headache, diarrhea, vomiting and abdominal pain.

Visit www.who.int for more information from the World Health Organization on Ebola, and to stay alert about the epidemic.