infectious diseases
Marburg and Ebola Virus Infections
Transmission of Marburg and Ebola viruses
Most index cases involve exposure to nonhuman primates in sub-Saharan Africa. The vector and reservoir are not known precisely, although the Marburg virus has been identified in bats, and cases have occurred in people exposed to bats (eg, in mines or caves). Ebola virus outbreaks have been linked to consumption of meat from wild animals in affected areas (bush meat) or soup made from bats. Ebola and Marburg virus infections have also occurred after handling tissues from infected animals. Filoviruses are highly contagious. Human-to-human transmission occurs via skin and mucous membrane contact with body fluids (saliva, blood, vomit, urine, stool, sweat, breast milk, semen) of an infected symptomatic person or rarely a nonhuman primate. Humans are not infectious until they develop symptoms. Symptoms and signs persist in surviving patients for as long as it takes to develop an effective immune response. Typically, surviving patients eliminate the virus entirely and no longer transmit the virus; however, Ebola virus may persist in certain immune-privileged sites (eye, brain, testes). The virus may re-emerge from these sites and cause late sequelae or relapse, and sexual transmission from survivors to susceptible individuals is suspected. Marburg virus transmission via infected semen has been documented up to 7 weeks after clinical recovery ( General references ). Ebola virus genetic material persisted for a year or longer in the semen of 63% men who recovered from Ebola. However, PCR tests cannot determine whether live Ebola virus is present and capable of spreading disease. However, one man transmitted the virus to his sex partner > 500 days after he first had symptoms of the infection, indicating that the infectious virus can persist and be transmitted. It is possible that Ebola can be spread through sexual or other contact with semen ( Aerosol transmission has been suspected in a few instances; however, if it occurs, it is probably rare. During an outbreak, transmission is mainly human-to-human, resulting from close contact with the blood, secretions, other body fluids, or organs of infected people. Burial ceremonies in which the body is washed and in which mourners have physical contact with the deceased have played an important role in transmission of infection. 