Ebola Hemorrhagic Fever and Marburg Hemorrhagic Fever

media coverage when outbreaks occur. The causative organisms are found in tropical Africa and the Philippines. They belong to the Filoviridae family. Clinical presentations of the viral infections they cause share many common characteristics. At least 6 Marburg virus outbreaks and 21 Ebola virus outbreaks have been documented to date (Table 1). More outbreaks have probably occurred in remote areas before good documentation efforts could be made. The infections can be difficult to study because outbreaks are sporadic and typically occur in high-conflict areas. There is no cure or specific treatment for infections caused by either Ebola virus or Marburg virus, and the case-fatality rate for Ebola virus infection in particular is high. Supportive care is the only therapy currently available, and strict infection control measures are essential to preventing the spread of the virus during an outbreak. Epidemiology and transmission Both viruses tend to be—but are not always—geographically restricted. Infectious outbreaks are sporadic and unpredictable, primarily occurring in the tropics and usually among rural, indigenous workers. Ebola virus outbreaks also appear to be associated with the end of rainy seasons that have sharply drier conditions than what is common.1 Humans are not the natural reservoir for either virus. Nonhuman primates also become infected, and because they seem to suffer the same fate as infected humans, they likely are not reservoirs either. Although intensive efforts to find the natural reservoirs of Ebola and Marburg viruses have been made, little definitive success has been achieved in this endeavor. No reservoir has been identified for Ebola virus to date despite the fact that 4700 mammals have been tested, whereas bats and possibly rodents have been found to harbor Marburg virus.2-5 Animal-to-human transmission of the virus also has been documented by contact with both slaughtered and live animals, including