The World Health Organization announced today, Saturday, six additional laboratory-confirmed cases of Marburg virus in Equatorial Guinea, bringing the total number of cases of the disease to 15. The Marburg virus causes a highly contagious hemorrhagic fever, with a mortality rate of up to 88 percent, as reported by the organization. The Marburg virus belongs to the same family as the Ebola virus, which has claimed thousands of lives in West Africa.