Pathogen Chronicle · Family Filoviridae

The history of the world's
most lethal hemorrhagic fevers

Ebola and Marburg viruses share a family, a transmission pattern, and a half-century of spillovers from the forests of Central Africa. Neither has a broadly available treatment. Together they account for thousands of deaths across more than 60 recorded outbreaks — most of which the world outside the affected region never heard about.

60+
Recorded outbreaks · 1967–2026
~16,000
Deaths · filovirus outbreaks total
12
Countries with confirmed Marburg
0
Broad-spectrum filovirus treatments
Geographic spread of Orthoebolavirus outbreaks
13 major events · 1976–2026 · Africa
Ebola (EBOV/Zaire)
Sudan (SUDV)
Bundibugyo (BDBV)
Spread vector
Six species — one family
Genus Orthoebolavirus
Orthoebolavirus zairense
EBOV · Zaire
The original and most-studied species. Caused the 2014–16 West Africa catastrophe and the 2018–20 Kivu outbreak — the two largest in history. The only Ebola with a licensed vaccine (Ervebo) and approved treatments (mAb114, REGN-EB3).
CFR range ~60–90% · untreated
Orthoebolavirus sudanense
SUDV · Sudan
First detected simultaneously with Zaire virus in 1976 but in Sudan, 850 km away. Lower CFR but recurs in Uganda. No licensed vaccine. The 2022 Mubende outbreak — no Ervebo, no mAb treatment — reminded the field how vulnerable SUDV leaves patients.
CFR range ~41–65% · untreated
Orthoebolavirus bundibugyoense
BDBV · Bundibugyo
Identified in 2007 during an outbreak in western Uganda's Bundibugyo District. Causes the active 2025–26 PHEIC in DRC and Uganda. Lower CFR than Zaire historically, but no vaccine, no targeted treatment. Current outbreak is only the third known event.
CFR ~25–31% · historical range
Orthoebolavirus taiense
TAFV · Taï Forest
A single confirmed human case in 1994 — a scientist who performed a necropsy on an infected chimpanzee in Côte d'Ivoire and survived. No known subsequent human infections. Studied for its phylogenetic relationship to the other species.
1 case · 0 deaths · isolated event
Orthoebolavirus restonense
RESTV · Reston
First detected in macaques imported to Reston, Virginia from the Philippines in 1989. Several humans seroconverted but none became ill. Not considered pathogenic to humans. Its presence in Philippine pigs raised questions about an expanded host range.
0 human deaths · not pathogenic
Orthoebolavirus bombaliense
BOMV · Bombali
Discovered in Sierra Leone in 2018 in two species of free-tailed bats. No confirmed human infections have ever been documented. Its characterization is ongoing and it remains the least understood of the six species — a reminder that the known range of filovirus diversity may be incomplete.
No confirmed human cases · bat reservoir
Major outbreaks, 1976–2026
Confirmed cases · deaths · CFR
Chronology
All 13 major events in sequence
Geographic spread of Orthomarburgvirus outbreaks
12 major events · 1967–2026 · Africa (primary)
Marburg virus
Ravn virus
🦇
Confirmed bat reservoir site
Spread / import
The confirmed reservoir and the candidate treatment pipeline
Genus Orthomarburgvirus · 2 known species
Orthomarburgvirus marburgense
MARV · Marburg virus
Responsible for the overwhelming majority of outbreaks. The 2004–05 Angola outbreak remains the deadliest at 88% CFR and 374 cases. The 2024 Rwanda outbreak, with 23% CFR, showed that earlier treatment and better infection control can shift outcomes dramatically.
Typical CFR range 24–88%
Orthomarburgvirus ravnense
RAVV · Ravn virus
Originally isolated from a single case in Kenya in 1987 (the "Ravn" case), Ravn was reclassified as a distinct species in 2011. It was also identified in the 1998–2000 Durba, DRC outbreak. Phylogenetically distinct from MARV; its specific epidemiology remains incompletely characterized.
Limited data · few confirmed events
Reservoir host
Rousettus aegyptiacus
The Egyptian fruit bat is the confirmed reservoir for Marburg virus — the only filovirus with a definitively identified natural host. Fruit bats show no illness. They roost in large colonies in caves and abandoned mines across sub-Saharan Africa and into the Middle East, creating predictable spillover risk at cave-entry sites.
Confirmed · PCR and serology evidence
Vaccine pipeline
rVSV-MARV · ChAd3-MARV · mRNA
Unlike Ebola, no Marburg vaccine has cleared full approval. Several candidates using the same viral-vector platform as Ervebo (VSV-based) are in Phase I/II trials, with accelerated studies triggered by the 2023–24 outbreaks. WHO has listed Marburg as a priority pathogen for emergency-use assessment.
No approved vaccine as of 2026
Major outbreaks, 1967–2026
Confirmed cases · deaths · CFR · bat cave links where known
Chronology
12 major events from Marburg, Germany to Jinka, Ethiopia