The Associated Press

Fri, Oct 10, 2008 (3:33 a.m.)

The U.N. health agency says it is investigating a mystery disease that killed three people in the South African city of Johannesburg.

The World Health Organization says the disease appears to be a form of hemorrhagic fever.

It says tests have proved negative for Ebola, Lassa fever, Rift Valley fever, Marburg fever and other main types of hemorrhagic fever.

WHO spokesman Gregory Hartl says the first death on Sept. 13 was a tour guide who had fallen ill in Zambia before being evacuated to South Africa. Two further deaths on Sept. 30 and Oct. 4. involved a paramedic and a nurse who treated the woman.

Hartl said Friday that 121 people are being monitored and WHO hopes to receive further test results by Sunday.