Story highlights Dr. Alan Jamison says he volunteered in the Liberian capital of Monrovia

He returned to the United States on July 25

He plans to be in isolation for 21 days

Two American medical workers have been infected with Ebola in West Africa

A retired American doctor who was working with Ebola patients in West Africa returned to the United States -- and put himself in quarantine.

Dr. Alan Jamison volunteered in the Liberian capital of Monrovia this month as part of an international medical group. He returned to the United States on July 25, according to Medical Teams International, the organization he worked with.

MTI declined to discuss details of how Jamison traveled back to the United States, including whether he was on a commercial flight.

Jamison, 69, said he's had no symptoms of the deadly virus, but has been in seclusion since he returned to his hometown of Morristown, Tennessee.

He plans to be in isolation for 21 days, which is the incubation period for the disease -- or the time between infection and onset of symptoms.

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"My last encounter with a patient who had Ebola was on July 19," he said. "I contacted the Centers for Disease Control and Prevention on my arrival ... and informed them I had been in West Africa and my history."

The father of three said his daughter picked him up from the airport and dropped him at home, where he's quarantined himself and has had no contact with anyone since.

"I'm feeling normal and doing the typical things a person would do in their home," he said. " I have my family who can bring me food if I need anything, and they would not enter the house. They can leave items outside the home."

Ebola spreads through contact with organs and bodily fluids such as blood, saliva, urine and other secretions of infected people.

Patients are only contagious when they show symptoms, not during the incubation period, according to the World Health Organization.

"I was not concerned that I was contagious when I left Africa, and not concerned at this time because I have no symptoms of the disease," Jamison said.

The retired pediatrician said he was volunteering with Medical Teams International.

"It was very stressful and emotional to see these things in Liberia," Jamison said.

Liberia is one of three nations battling an outbreak of Ebola. The World Health Organization says Ebola has been confirmed or suspected to have infected more than 1,300 people, with more than 700 deaths in West Africa this year.

So far, the disease has been confined to Liberia, Sierra Leone and Guinea. One man died in quarantine in Nigeria after leaving Liberia.

Two American medical workers infected in West Africa will receive treatment in Atlanta.

Dr. Kent Brantly arrived in Georgia on Saturday aboard a specially equipped plane and was taken to Emory University Hospital.

The plane is headed to Liberia to retrieve the other American, fellow missionary Nancy Writebol

The treatment of the patients will be conducted under strict safety protocols, U.S. officials said.

There's no cure for Ebola. The most common approach is to support organ functions and keep up bodily fluids such as blood and water long enough for the body to fight off the infection.

Despite the risks, Jamison said he'd return to West Africa to help combat Ebola.