VOINJAMA, Liberia (CNN) -

Two more medical workers have survived Ebola.

Dr. Senga Omeonga and physician assistant Kynda Kobbah were discharged from a Liberian treatment center on Saturday after recovering from the virus, according to the World Health Organization.

They were given ZMapp -- the experimental drug that's credited with saving the lives of two Americans infected with Ebola.

Officials said that early treatment was key to the recovery of the Liberian medical workers. Both indicated that they will return to work soon.

The WHO says that they were received by Liberia's president after being discharged. A third person who was infected and treated with ZMapp died last Sunday.

The lethal virus has spread to five countries in West Africa -- Liberia, Guinea, Sierra Leone, Nigeria and Senegal -- during this year's outbreak. Senegal confirmed its first case of the virus on Friday, one week after closing its border with Guinea, the Senegalese Press Agency reported.

There have been 3,069 probable, confirmed and suspected cases of Ebola in West Africa -- more than 40% of which have occurred within the past three weeks, according to the WHO. Some 1,552 of those have died.