Peace Corps is pulling volunteers out of three African nations over Ebola fears. 

At least two U.S. Peace Corps volunteers in Liberia have been exposed to Ebola and are being isolated and monitored, CBS News reports.

They are not showing signs of sickness.

The incubation period for Ebola is up to 21 days.

Here is the Peace Corps statement:

Peace Corps Removing Volunteers in Liberia, Sierra Leone and Guinea

WASHINGTON, D.C., July 30, 2014 - The Peace Corps today announced that it is temporarily removing its volunteers from Liberia, Sierra Leone and Guinea due to the increasing spread of the Ebola virus. The agency has been and will continue to closely monitor the outbreak of the virus in collaboration with leading experts from the Centers for Disease Control and Prevention (CDC) and the U.S. Department of State.

The Peace Corps has enjoyed long partnerships with the government and people of Liberia, Sierra Leone and Guinea and is committed to continuing volunteers' work there. A determination on when volunteers can return will be made at a later date. 

In recent months, the Peace Corps has provided volunteers in adjacent areas of Liberia, Sierra Leone and Guinea with guidance to ensure they take the utmost precautions to protect their health. Transmission of Ebola virus requires direct contact with bodily fluids from a sick, infected individual, and individuals who are infected but not yet sick are not considered contagious. For more information on the Ebola virus, please visit www.cdc.gov.

There are currently 102 volunteers in Guinea working in the areas of education, agriculture and health; and 108 volunteers in Liberia and 130 volunteers in Sierra Leone working in education. All Peace Corps programs have emergency action plans specific to that country in place, and staff and volunteers are trained and prepared to respond in situations like this one.