A third United Nations employee has been killed by the deadly Ebola virus in the West African country of Sierra Leone.

According to UN spokesman Stephane Dujarric on Monday, a driver for the UN Women agency, succumbed to the virus over the weekend in Sierra Leone.

"All measures to protect staff at the duty station in Sierra Leone are being taken as best as possible under the current circumstances," said Dujarric.

A statement by the UN Women agency said that the deceased who had been a driver for the agency since 2005 passed away on Saturday following testing positive for the virus.

He was quarantined on October 14 following his wife showing symptoms of the virus. The wife is still under care at an Ebola treatment center and a UN medical team is trying to trace all the persons who came into contact with the man.

Earlier this month, a Sudanese UN health worker died in Germany after caring for Ebola victims in Liberia.

And the first UN staffer casualty was a Liberian woman who had worked for the peacekeeping mission in Liberia for nearly a decade. She fell ill on September 20 and died on September 22.

Ebola is a form of hemorrhagic fever whose symptoms are diarrhea, vomiting and bleeding.

The virus spreads through direct contact with infected blood, feces or sweat. It can also be spread through sexual contact or the unprotected handling of contaminated corpses.

Ebola remains one of the world’s most virulent diseases and kills between 25 to 90 percent of those who contract the disease. There is currently no known cure for Ebola.

According to the latest World Health Organization (WHO) figures, the Ebola outbreak in West Africa has killed more than 4,500 people across Liberia, Guinea and Sierra Leone.