Viral haemorrhagic fever (VHF): what it is and how it spreads

Viral haemorrhagic fevers are a group of severe, often life-threatening illnesses caused by viruses from several different families. They typically begin with fever and non-specific symptoms; in severe cases they can progress to bleeding, shock and multi-organ failure. Not every patient bleeds, and the risk, transmission route and treatment differ sharply from one virus to another.

Last reviewed: 7 October 2026 · Independent archive

Diagram of virus families causing viral haemorrhagic fevers: Filoviridae, Arenaviridae, Nairoviridae, Flaviviridae, Phenuiviridae, Hantaviridae — Viral haemorrhagic fevers are caused by viruses from several unrelated families.

Which viruses cause viral haemorrhagic fever?

VHFs are not a single disease. A 2024 review in Pathogens lists viruses from the families Arenaviridae, Filoviridae, Flaviviridae, Hantaviridae, Nairoviridae, Peribunyaviridae and Phenuiviridae as causes. The table compares the diseases most often discussed in international preparedness work.

Selected viral haemorrhagic fevers compared
Disease	Virus family	Main source / reservoir	Person-to-person spread	Licensed vaccine
Ebola virus disease	Filoviridae	Fruit bats considered likely host	Yes, via blood and body fluids	Yes, for Zaire ebolavirus only
Marburg virus disease	Filoviridae	Egyptian rousette bat	Yes, via blood and body fluids	No
Crimean-Congo HF	Nairoviridae	Hard ticks (mainly Hyalomma); livestock as amplifying hosts	Yes, via blood and tissues	No
Lassa fever	Arenaviridae	Rodents (urine and faeces)	Yes, mainly in health-care settings	No
Rift Valley fever	Phenuiviridae	Livestock, mosquitoes	Not typical	No human vaccine licensed for general use
Yellow fever	Flaviviridae	Mosquitoes	No	Yes

Rift Valley fever illustrates how variable VHFs are: most infections are mild, and the haemorrhagic form affects only a minority of patients.

How viral haemorrhagic fevers spread

Each virus first reaches humans from an animal source – bats, rodents, ticks, mosquitoes or livestock. Some, including Ebola, Marburg, Lassa and CCHF, can then spread between people through direct contact with blood or other body fluids of an infected person. That is why health workers and family caregivers carry a particular risk when protective measures are missing.

Animal contact: bats in caves or mines (Marburg), rodent-contaminated food or household items (Lassa), blood of infected livestock (CCHF).
Vectors: tick bites (CCHF), mosquito bites (yellow fever, Rift Valley fever).
Human contact: blood, secretions and other body fluids of patients, contaminated objects such as needles or bedding, and unsafe burial practices.

Symptoms and course of illness

Early illness usually looks like many other infections: sudden fever, headache, muscle pain, weakness, and often vomiting or diarrhoea. In severe cases, haemorrhagic signs can follow – bleeding from gums, nose or injection sites, small skin bleeds – together with shock and organ failure. Bleeding is not universal, so its absence does not rule out a VHF.

Incubation periods for the diseases covered here generally fall within a range of a few days to three weeks. This is why follow-up of exposed contacts in outbreaks commonly lasts 21 days.

Why diagnosis is difficult

The early phase resembles malaria, typhoid fever, shigellosis and other common febrile illnesses in the same regions. Travel history and exposure history are therefore essential. Confirmation relies on laboratory testing, usually RT-PCR in the acute phase, performed under strict biosafety conditions. See laboratory diagnostics for VHF.

Treatment and vaccines

For most VHFs, treatment is supportive: fluids and electrolytes, oxygen, blood pressure support and treatment of complications. Specific options exist only for a few diseases. For Ebola caused by Zaire ebolavirus, monoclonal antibody therapies and a licensed vaccine are available. For Lassa fever, ribavirin is used early in the illness. For CCHF, Marburg and most others, no licensed vaccine is in routine use.

Prevention

Avoid contact with blood and body fluids of sick people and with dead bodies in affected areas.
Use protective clothing and repellents against ticks in CCHF-endemic rural areas; avoid unprotected contact with livestock blood.
Store food in rodent-proof containers and keep homes clean in Lassa-endemic areas.
Avoid entering caves or mines inhabited by fruit bats where Marburg virus occurs.
In health facilities: consistent infection prevention and control – see infection prevention & control.

Medical note: this page summarises public-health sources for general information. It is not medical advice. If you develop fever after travel to an affected area or after contact with a patient or with animal blood or ticks, contact a doctor or your local health authority by phone before attending in person, and mention the exposure.

Frequently asked questions

Is every viral haemorrhagic fever contagious between people?

No. Ebola, Marburg, Lassa and CCHF can spread between people through blood and body fluids. Yellow fever and Rift Valley fever are not typically transmitted from person to person.

Do all patients with VHF bleed?

No. Bleeding occurs mainly in severe cases. Many patients have only fever and non-specific symptoms, and some infections are mild or without symptoms.

Is there a vaccine for viral haemorrhagic fever?

Only for some. Licensed vaccines exist for yellow fever and for Ebola caused by Zaire ebolavirus. There is no licensed vaccine in routine use for Marburg, Lassa or CCHF.

Where do viral haemorrhagic fevers occur?

Mostly in tropical and subtropical regions of Africa, the Middle East, Asia and South America. CCHF also occurs in parts of south-eastern Europe.

How are VHFs diagnosed?

By laboratory tests, mainly RT-PCR during the acute phase and antibody tests later, carried out under strict biosafety conditions. Travel and exposure history guide who gets tested.