New Delhi, Oct. 8 -- WHO director of Epidemic and Pandemic Management Maria Van Kerkhove said Wednesday the UN health agency doesn't know how a 28-year-old lab worker in Siberia, who worked at the Irkutsk Anti-Plague Research Institute in Siberia, died.

She urged Russia to provide more information about a case that has prompted global concerns about suspected pneumonic plague. The United States and the European Union have also urged Moscow for more information after the death of the 28-year-old woman.

Van Kerkhove said the agency doesn't know what the "causative agent" was behind the woman's October 2 death, which unconfirmed reports in Russia blamed on pneumonic plague - a less common but severe form of plague that can spread from pers...