A top official with the World Health Organization says the U.N. health agency doesn’t know how a lab employee in Siberia died amid concerns about plague. She called on Russia to provide more information. Maria Van Kerkhove is WHO director of Epidemic and Pandemic Management. She said the agency doesn’t know what the 'causative agent’ was behind the woman’s Oct. 2 death, and “this is why we need more information.” Russian authorities have kept a tight lid on information about the case, which has been surrounded by secrecy.