Marburg reported in 1 of 8 initial samples in first-ever outbreak in Equatorial Guinea

On Feb. 13, Equatorial Guinea and WHO reported nine deaths and 16 suspected cases in the nation’s western Kie Ntem province consistent with Marburg virus disease. Laboratory tests on samples from eight initial patients at the Institut Pasteur in Dakar, Senegal, showed one was positive for Marburg virus. Why none of the other seven patient samples tested positive for Marburg was not addressed nor was the type of diagnostic test specified, e.g., antigen test or PCR. Whole-genome sequencing of the Marburg virus from patients will be essential to optimize diagnostic tests and, if undertaken, candidate vaccine studies.

An epidemiological link to a funeral appeared in the initial report of the outbreak. More than 200 persons had been quarantined as of last week. Like Ebola virus, Marburg is a filovirus and has multiple similarities in terms of incubation period, clinical manifestations and a variably high case fatality rate that can be lowered with good supportive management including appropriate fluid rehydration. Unlike Ebola virus, however, a full-length replication-competent Marburg virus has been isolated from the African fruit bat (its reservoir host).

There are no licensed vaccines, antiviral drugs or antiviral monoclonal antibodies for Marburg virus. There are several vaccine candidates, including one that uses a vesicular stomatitis virus vector and another that uses a modified vaccinia Ankara vector. (For more information, see this related article from Gavi, the Vaccine Alliance.)

If this outbreak expands and persists, then discussion of a clinical trial with candidate vaccines and/or antivirals may occur.

Marburg has never been reported in Equatorial Guinea. The largest outbreaks have been reported in Angola and the Democratic Republic of Congo, with smaller outbreaks in Uganda, Kenya, South Africa, Guinea, Ghana and, outside Africa, in Germany in 1967 (in Marburg and Frankfurt, as well as in 1967 in Belgrade, Serbia, linked with imported nonhuman primates), the Netherlands and the USA (one traveler each returning from Uganda in 2008). On its website, the U.S. CDC has a chronology of Marburg outbreaks including the number of known cases, deaths and fatality rates.