Viral Hemorrhagic Fever (VHFs)
Viral Hemorrhagic Fever (VHF) is a group of illnesses that are caused by several distinct families of viruses. It is a severe multisystem syndrome. Some of these viruses cause mild illnesses, and many of these cause severe, life-threatening diseases. Many of these viruses are Biosafety level four (BSL-4) pathogens.
These viruses naturally reside in an animal reservoir host (rat, mouse, or other rodents) or arthropod vector. Humans get infections when they come in contact with infected animals either directly or via vectors such as ticks and mosquitoes. The vectors of Marburg and the Ebola virus are not known yet.
VHFs are caused by viruses of four distinct families:
- Arenaviridae: Lymphocytic choriomeningitis virus (LCMV), Lassa virus; (Arenavirus)
- Filoviridae: Marburg, Ebola
- Bunyaviridae: Orthobunyavirus, Hantavirus, Nairovirus, Phlebovirus
- Flaviviridae: Flavivirus e.g. Dengue, Japanese encephalitis virus, Yellow fever virus, Zika virus.
Common properties of viruses causing VHFs
- Enveloped RNA viruses
- Natural reservoir: animal or insect host not humans.
- Humans are infected when they come into contact with infected hosts.
- Geographical restriction
- There is no cure or established drug treatment for VHFs with some exceptions.
Diseases caused by these viruses
- Dengue hemorrhagic fever (DHF)
- Marburg hemorrhagic fever
- Ebola hemorrhagic fever
- Lassa fever
- Crimean-Congo hemorrhagic fever (CCHF)
- Hendra virus disease
- Kyasanur Forest disease (KFD)
- Lujo hemorrhagic fever (LUHF)
- Omsk hemorrhagic fever (OHF)
- Rift Valley fever (RVF)
- Chapare hemorrhagic fever (CHHF)
Vaccines are available for yellow fever and Argentine hemorrhagic fever that can protect against these diseases to some extent.
Prevention of Viral Hemorrhagic Fever can be achieved by either control of rodents, protecting from the bite of vectors, or avoiding close contact with infected individuals
1. Avoiding contact with host species i.e. rodents
Because many of the hosts that carry hemorrhagic fever viruses are rodents, disease prevention efforts include:
- controlling rodent populations;
- discouraging rodents from entering or living in homes or workplaces;
- encouraging safe cleanup of rodent nests and droppings
2. For those hemorrhagic fever viruses that are spread by arthropod vectors prevention efforts include:
- Control of insect and arthropod vectors
- Use of insect repellants
- Wearing proper clothing which covers most of the body part
- Using bed nets, window screens, and other insect barriers to avoid being bitten by insects.
3. For those hemorrhagic fever viruses that can be transmitted from person to person prevention efforts include:
- Avoiding close physical contact with infected people and their body fluids
- Infected individuals must be isolated and the nursing/physician must wear protective clothing while caring or treating them.
- Proper use, disinfection, and disposal of instruments and equipment used in treating or caring for patients with viral hemorrhagic fever, such as needles and thermometers.