Another Outbreak of Hemorrhagic Fever in Africa: Marburg Virus
abstract & commentary
Synopsis: An outbreak of hemorrhagic fever resembling Ebola virus infection was demonstrated to be due to the related Marburg virus.
Source: WHO Weekly Epidemiologic Record 1999;74(20, 21):157-164. http://www.healthnet.org/programs/promed. html#archives; http://www.cdc.gov/ncidod/dvrd/spb/ mnpages/dispages/marburg.htm.
Beginning in april 1999, cases of hemorrhagic fever began appearing in the Democratic Republic of the Congo (formerly Zaire). While originally thought to be the result of Ebola virus infections, this outbreak has been demonstrated to be due to the related filovirus, Marburg virus.
At least 72 suspected cases of viral hemorrhagic fever (VHF) have been identified and approximately 60 patients have been reported to have died of hemorrhagic fever in Watsa and nearby Durba. However, the actual proportion of these cases that are due to Marburg virus infection remains uncertain. The outbreak has predominantly affected young males, with the majority being involved in gold mining in Durba. Intrafamilial chains of transmission have been observed.
All five patients with virologically confirmed Marburg infections died. The first of these was the Chief Medical Officer of the Watsa zone who died on April 23, 1999, and whose infection was confirmed by the National Institute for Virology in South Africa. A woman who had reportedly lived 20-30 km from Durba died on May 7 in the isolation unit of the health center. The third confirmed case was that of a gold miner who died on May 13.
Comment by Stan Deresinski, MD, FACP
The Marburg virus has, like Ebola, a genome of a single strand of negative sense RNA and a characteristic filamentous morphology. Marburg virus was first discovered in 1967, after an outbreak of hemorrhagic fever involving laboratory workers at the Behrinc Company in Marburg and the Paul Ehrlich Institute in Frankfurt, Germany, as well as Belgrade, Yugoslavia. The 31 affected individuals had either been working with kidneys from African Green monkeys for production of cells for in vitro cultivation or had been in contact with someone who did. The virus, first characterized in Marburg, Germany, was isolated from sick monkeys in a single shipment from Uganda. Serologic studies, however, failed to identify evidence of infection in natural living monkeys captured in Uganda.
The virus was not again encountered until 1975 when three cases, including a secondary case in a treating nurse, were identified in southern Africa. After another "eclipse" period of five years, two cases, including one in an attending physician, were identified; the index case had become ill in an area of western Kenya not far from the area in which the monkeys affected in 1967 had been captured. A single case was identified in 1987 near this same area.
The clinical syndrome caused by Marburg is identical to that caused by Ebola virus. The incubation period is usually 4-10 days (mean 7 days; range 2-21 days) and is terminated by the abrupt onset of fever, headache, arthralgia, and myalgia. Bradycardia, pharyngitis, and conjunctivitis may occur and some patients develop a maculopapular measles-like skin eruption that may subsequently desquamate. The patients may then develop diarrhea, abdominal pain, and vomiting and, with the onset of hemorrhagic manifestations after the third day of illness, hematemesis, along with cutaneous manifestations of bleeding. Fluid shifts may result in edema.
Lymphocytopenia occurs early in the illness, followed by neutrophilia and thrombocytopenia. While abnormal platelet aggregation can be detected, laboratory evidence of disseminated intravascular coagulation is absent. Hemorrhagic manifestations are likely the result of endothelial damage, together with the numerical and functional platelet deficiency. Serum transaminases are elevated, with the AST being higher than the ALT.
The natural reservoirs of both Marburg and Ebola viruses remain unknown. The virus is transmitted to humans through contact with infected animals or animal tissue; person-to-person transmission occurs as the result of close contact with infected patients and body fluids. Patients with suspected filovirus infection should be isolated and barrier nursing techniques strictly enforced.
Reference
1. Huggins JW. Filoviridae. In: Richman DD, Whitley RJ, Hayden FG, eds. Clinical Virology. New York, NY; 1997:899-909.
Which of the following is incorrect with regard to Marburg virus infection?
a. The recent outbreak (April-May 1999) of hemorrhagic fever in the Democratic Republic of the Congo has predominantly affected young males, particularly those involved in gold mining.
b. The Marburg virus is an RNA virus.
c. Marburg virus causes a disease that is much milder than that caused by Ebola virus, with a low case-fatality ratio.
d. Secondary human cases due to Marburg virus infection have been observed to occur.
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