Causative agent. Marburgvirus of the Filoviridae family.
Geographical occurrence. Outbreaks and sporadic cases have been reported in Angola, Democratic Republic of Congo, Kenya, and South Africa (in a person with a recent travel history to Zimbabwe). The initial outbreaks, in Germany and the former Yugoslavia in 1967, have been linked to laboratory work using African green monkeys (Cercopithecus aethiops) imported from Uganda.
Transmission. Transmission of the virus from person to person requires extremely close contact with a patient. Infection results from contact with blood or other body fluids (faeces, vomitus, urine, saliva, and respiratory secretions) with high virus concentration, especially when these fluids contain blood. Transmission via infected semen can occur up to seven weeks after clinical recovery.
Infection through casual contact is thought to be exceedingly rare. The low rate of transmission to persons with casual contact suggests that aerosol transmission via the respiratory tract is not efficient, if it occurs at all. Transmission does not occur during the incubation period.
Patients appear to be most infectious during the phase of severe illness accompanied by haemorrhagic manifestations. Close contact with a severely ill patient, during care at home or in hospital, and certain burial practices are common routes of infection. Transmission via contaminated injection equipment or through needle-stick injuries is associated with more severe disease, rapid deterioration, and possibly higher fatality.
Incubation period. 3 to 9 days.
Susceptibility. All age groups are susceptible to infection, but most cases have occurred in adults. Prior to the present outbreak in Angola, paediatric cases were considered extremely rare. In the largest outbreak previously recorded, which occurred in the Democratic Republic of Congo from late 1998 to 2000, only 12 (8%) of the cases were under the age of 5 years.
Clinical features. Illness caused by Marburg virus begins abruptly, with severe headache and severe malaise. Muscle aches and pains are a common feature.
A high fever usually appears on the first day of illness, followed by progressive and rapid debilitation. A severe watery diarrhoea, abdominal pain and cramping, nausea, and vomiting begin about the third day. Diarrhoea can persist for a week. The appearance of patients at this phase has been described as showing “ghost-like” drawn features, deep-set eyes, expressionless faces, and extreme lethargy. In the 1967 European outbreak, a non-itchy rash was a feature noted in most patients between days 2 and 7 after symptom onset.
Many patients develop severe haemorrhagic manifestations between days 5 and 7, and fatal cases usually have some form of bleeding, often from multiple sites. Findings of fresh blood in vomitus and faeces are often accompanied by bleeding from the nose, gums, and vagina. Spontaneous bleeding at venipuncture sites can be particularly troublesome. During the severe phase of illness, patients have sustained high fevers. Involvement of the central nervous system can result in confusion, irritability, and aggression. Orchitis has been reported occasionally in the late phase of disease (day 15).
In fatal cases, death occurs most often between 8 and 9 days after symptom onset, usually preceded by severe blood loss and shock.