Studies of Reservoir Hosts for Marburg Virus

Abstract

To determine reservoir hosts for Marburg virus (MARV), we examined the fauna of a mine in northeastern Democratic Republic of the Congo.The mine was associated with a protracted outbreak of Marburg hemorrhagic fever during 1998-2000.We found MARV nucleic acid in 12 bats, comprising 3.0%-3.6% of 2 species of insectivorous bat and 1 species of fruit bat.We found antibody to the virus in the serum of 9.7% of 1 of the insectivorous species and in 20.5% of the fruit bat species, but attempts to isolate virus were unsuccessful.M arburg virus (MARV) and Ebola virus, members of the family Filoviridae, cause outbreaks of severe hemorrhagic fever in Africa.Although humans have on occasion acquired infection from contact with tissues of diseased nonhuman primates and other mammals, the reservoir hosts of the viruses in nature remain unknown.An outbreak of Marburg hemorrhagic fever ran a protracted course in the gold-mining village of Durba, northeastern Democratic Republic of the Congo, from October 1998 through September 2000.The outbreak involved 154 patients (48 confi rmed and 106 suspected cases); the casefatality ratio was 83% (1).Primary cases occurred in young male miners and spread as secondary cases to family members and, less frequently, to healthcare workers and others in the community.Most cases occurred in Durba, but a few secondary cases occurred elsewhere, including nosocomial infections in nearby Watsa village, where severely ill patients sought care.The occurrence of sporadic cases and short chains of human-to-human transmission suggested that infection had been repeatedly introduced into the human population; this suggestion was substantiated by the detection of at least 9 genetically distinct viruses circulating during the outbreak.Identical sequences of MARV were found in patients within but not across clusters of epidemiologically linked cases, although viruses with the same sequences reappeared at irregular intervals during the outbreak.Most (94%) affected miners worked underground in Goroumbwa Mine, rather than in the 7 opencast mines in the village.Cessation of the outbreak coincided with the fl ooding of Goroumbwa Mine.Interviews with long-term residents and healthcare workers and review of hospital records showed that a syndrome hémorragique de Durba [hemorrhagic syndrome of Durba] had been associated with the mine since at least 1987, and a survivor of a 1994 outbreak was found to have antibodies against MARV.The fauna of Goroumbwa Mine included bats, rodents, shrews, frogs, snakes, cockroaches, crickets, spiders, wasps, and moth fl ies (1).We present the results of virus reservoir host studies conducted during the outbreak.