Viral Haemorrhagic Fevers (Human)

Primary reference(s)

WHO, no date. Haemorrhagic fevers: Viral. World Health Organization (WHO). Accessed 13 December 2019.

Additional scientific description

The term ‘viral haemorrhagic fever’ is used to describe a severe multisystem syndrome (multisystem in that multiple organ systems in the body are affected). Characteristically, the overall vascular system is damaged, and the body’s ability to regulate itself is impaired. Symptoms are often accompanied by haemorrhage (bleeding); however, the bleeding is itself rarely lifethreatening. While some types of haemorrhagic fever viruses can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease (CDC, 2014).

Viruses associated with viral haemorrhagic fever naturally reside in animal reservoir hosts or arthropod vectors. They depend on their hosts for survival and so are usually restricted to the geographic area inhabited by those animals or arthropod vectors (PHE, 2018).

Viral haemorrhagic fever (viruses) include:

Arenaviridae

• Argentine haemorrhagic fever (Junin virus)
• Bolivian haemorrhagic fever (Machupo virus)
• Lassa fever (Lassa virus)
• Venezuelan haemorrhagic fever (Guanarito virus)
• Brazilian haemorrhagic fever (Sabia)
• Chapare haemorrhagic fever (Chapare)
• Lujo haemorrhagic fever (Lujo) 

Bunyaviridae

• Rift Valley Fever (Rift Valley Fever virus)
• Crimean-Congo haemorrhagic fever (Nairovirus)
• Hanta Virus Haemorrhagic fevers (Hantaviruses) 

Flaviviridae

• Yellow fever (Yellow fever virus)
• Dengue fever/dengue haemorrhagic fever (Dengue viruses)
• Omsk haemorrhagic fever (Omsk hemorrhagic fever virus)
• Kyasanur forest disease (Kyasanur Forest disease virus)
• Alkhurma disease (Alkhurma virus) 

Filoviridae

• Ebola (Ebolavirus)
• Marburg haemorrhagic fever (Marburgvirus)

Note that this is not an exhaustive list (CDC, 2018).

Humans may acquire viral haemorrhagic fever viruses when they come into close contact with live animal hosts, animal carcasses during slaughtering and/or animal droppings. Tick or mosquito bites can transmit some of the viruses, such as Crimean-Congo fever and yellow fever, between animal species, including humans. Dengue is currently the mosquito borne viral haemorrhagic fever with the highest public health impact worldwide with an estimate of 390 million infections every year in tropical areas where the Aedes mosquitoes are widespread (WHO, 2020).

For other viruses, animals are the host (PHE, 2018). Direct transmission of the virus through contact with the body fluids or secretions of infected patients is also possible for some of the viruses (WHO, no date).

Several viral haemorrhagic fevers are prone to outbreaks and epidemics with high case fatality rates. These include Ebola, Lassa fever and Crimean-Congo haemorrhagic fever. These diseases are part of the priority list for the World Health Organization (WHO) Research and Development Blueprint for Action to Prevent Epidemics (WHO, 2016a).

Because increasing numbers of people travel each year, outbreaks of these diseases are becoming an increasing threat in non-endemic areas (PHE, 2018).

Metrics and numeric limits

Not applicable.

Examples of drivers, outcomes and risk management

Viral haemorrhagic fevers occur widely in tropical and subtropical regions (WHO, no date).

Most of them have a non-human natural reservoir, with some transmitted by mosquitoes or ticks. A small number are preventable by vaccine (e.g., yellow fever) and others have potential vaccines and treatments in different stages of development (WHO, no date).

Prevention efforts must concentrate on avoiding contact with host species and they are often focused on controlling animal hosts and vector populations (PHE, 2018).