Ebola virus disease has killed 4,922 and infected 10,141 in eight countries since the beginning of the current outbreak, the World Health Organization reported Saturday. Most of the deaths have been in West Africa, the worst-hit region so far, the United Nations health agency said.

Two of the eight countries -- Nigeria and Senegal -- declared themselves Ebola-free Oct. 23, WHO reported. However, the health agency said the disease is still evident in the other six countries: Guinea, Liberia, Mali, Sierra Leone, Spain and the U.S.

Overall, 244 of the 450 health-care workers who contracted Ebola had died of the disease as of Thursday, WHO reported.

“WHO is undertaking extensive investigations to determine the cause of infection in each case. Early indications are that a substantial proportion of infections occurred outside the context of Ebola treatment and care,” the health agency said.

A 2-year-old girl who tested positive for Ebola in Mali Thursday died of the disease Friday. Hers represented the country’s first case during the current outbreak.

The American National Institutes of Health declared Friday the recovery of Nina Pham, a Dallas nurse who contracted the disease while treating the late Thomas Eric Duncan. U.S. health authorities are monitoring a number of people because of their exposure to Amber Joy Vinson, another Dallas nurse who contracted Ebola from Duncan, and Dr. Craig Spencer, a New York physician who contracted the disease in West Africa.