He said he did not know how the patients were doing since receiving the drug.

If the treatment works, Mr. Nyenswah said in an interview earlier in the week, “and we can save the doctors here, especially those senior medical doctors that are infected with the virus, then Liberia can be a place to do a mass trial with the drugs.”

Liberian health officials requested the serum after it was provided to two American development workers, Dr. Kent Brantly and Nancy Writebol, who contracted Ebola while working at ELWA Hospital, the same hospital where the three Liberian health care workers were given the drug. Dr. Brantly and Ms. Writebol were evacuated to Emory University Hospital in Atlanta, where they continue to be treated. But a third patient reported to have received ZMapp, Miguel Pajares, a Spanish missionary priest, has died.