GENEVA, Oct. 13 (Xinhua) -- Preliminary tests by scientists showed that the virus causing three deaths recently in South Africa and Zambia belongs to the same family as Lassa fever, according to a report released by the World Health Organization (WHO) on Monday.

    Scientists in South Africa and the United States are still going on with their research so as to learn more about the virus, WHO said.

    Investigation began after an office employee of a safari tour company in Zambia died on Sept. 14 in a hospital in Johannesburg, South Africa, two days after being transferred from Zambia.

    Two medical workers who had cared for the patient also died in early October after showing similar symptoms including fever, headaches, diarrhea and muscular pain, WHO reported.

    The UN agency said a fourth case has now been confirmed, with a nurse who had close contact with one of the earlier cases becoming ill and being admitted to hospital in South Africa.

    However, there is no need to restrict travel to the two countries, WHO said.