page_title: Bat virome
section_title: Marburgvirus and Ebolavirus
hierarchical_section_title: Bat virome / Negative-sense single-stranded RNA viruses / Filoviruses / Marburgvirus and Ebolavirus
caption_attribution_description: English: Lithuanian Zoological Gardens
context_page_description: Bat virome refers to the group of viruses associated with bats. Bats host a diverse array of viruses, including all seven types described by the Baltimore classification system: (I) double-stranded DNA viruses; (II) single-stranded DNA viruses; (III) double-stranded RNA viruses; (IV) positive-sense single-stranded RNA viruses; (V) negative-sense single-stranded RNA viruses; (VI) positive-sense single-stranded RNA viruses that replicate through a DNA intermediate; and (VII) double-stranded DNA viruses that replicate through a single-stranded RNA intermediate. The greatest share of bat-associated viruses identified as of 2020 are of type IV, in the family Coronaviridae.
  Bats harbor several viruses that are zoonotic, or capable of infecting humans, and some bat-borne viruses are considered important emerging viruses. These zoonotic viruses include the rabies virus, SARS-CoV, Marburg virus, Nipah virus, and Hendra virus. While research clearly indicates that SARS-CoV-2 originated in bats, it is unknown how it was transmitted to humans, or if an intermediate host, possibly the Sunda pangolin, was involved.
context_section_description: Filoviridae is a family of virus containing two genera associated with bats: Marburgvirus and Ebolavirus, which contain the species that cause Marburg virus disease and Ebola virus disease, respectively. Though relatively few disease outbreaks are caused by filoviruses, they are of high concern due to their extreme virulence, or capacity to cause harm to their hosts. Filovirus outbreaks typically have high mortality rates in humans. Though the first filovirus was identified in 1967, it took more than twenty years to identify any natural reservoirs.
  Ebola virus disease is a relatively rare but life-threatening illness in humans, with an average mortality rate of 50% (though individual outbreaks may be as high as 90% mortality). The first outbreaks were in 1976 in South Sudan and Democratic Republic of the Congo. The natural reservoirs of ebolaviruses are unknown. However, some evidence indicates that megabats may be natural reservoirs. Several megabat species have tested seropositive for antibodies against ebolaviruses, including the hammer-headed bat, Franquet's epauletted fruit bat, and little collared fruit bat. Other possible reservoirs include non-human primates, rodents, shrews, carnivores, and ungulates. Definitively stating that fruit bats are natural reservoirs is problematic; as of 2017, researchers have been largely unable to isolate ebolaviruses or their viral RNA sequences from fruit bats. Additionally, bats typically have low level of ebolavirus-associated antibodies, and seropositivity in bats is not strongly correlated to human outbreaks.
  Marburg virus disease (MVD) was first identified in 1967 during simultaneous outbreaks in Marburg and Frankfurt in Germany, and Belgrade, Serbia. MVD is highly virulent, with an average human mortality rate of 50%, but as high as 88% for individual outbreaks. MVD is caused by Marburg virus and the closely related Ravn virus, which was formerly considered synonymous with Marburg virus. Marburg virus was first detected in the Egyptian fruit bat in 2007, and is now recognized as the natural reservoir of the virus. Marburg virus has been detected in Egyptian fruit bats in Gabon, Democratic Republic of the Congo, Kenya, and Uganda. Spillover from Egyptian fruit bats occurs when humans spend prolonged time in mines or caves inhabited by the bats, though the exact mechanism of transmission is unclear. Human-to-human transmission occurs through direct contact with infected bodily fluids, including blood or semen, or indirectly through contact with bedding or clothing exposed to these fluids.
caption: The Egyptian fruit bat, a known natural reservoir of Marburg virus and Ravn virus, which cause Marburg virus disease
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