What are arenaviruses and how they affect us


Arenaviruses are single-stranded RNA viruses which are carried principally in rodents, from which they may be transmitted to humans. One group of New World arenaviruses (the Tacaribe complex) is responsible for South American haemorrhagic fevers. Lymphocytic choriomeningitis virus occasionally produces viral meningitis in humans. Lassa is an Old World arenavirus.


Since the first report in 1969, the disease has so far been limited to sub-Saharan West Africa, where serological studies have shown that past infection is widespread in rural areas. Isolated cases and small rural outbreaks are most common, but unlike other arenaviruses Lassa can spread person to person, and nosocomial outbreaks in hospital have also occurred .

Clinical features

The disease has the general features of a viral infection, high fever, intercostal myalgia, bradycardia, low blood pressure and leucopenia. Adherent yellow exudates on the pharynx are particularly characteristic. The fever lasts between 7 and 17 days. In severe cases liver and renal failure, electrolyte imbalance, haemorrhage and acute circulatory failure develop, hence the classification of Lassa fever as a viral haemor

Commons viral haemorrhagic fevers
Disease Viral agent Reservoir Transmission Geography Case mortality
Lassa fever Arenavirus Multimammate rat (Mastomys natalensis) Patient
  • Urine
  • Body fluids
West Africa Up to 50% (responds to tribavirin)
Marburg/Ebola virus disease Filovirus
  • ?
  • Patient
Via monkeys body fluids Central Africa 25-90%
Yellow fever Flavivirus Monkeys Mosquitoes Tropical Africa, South and Central America 10-60%
Dengue Flavivirus (dengue types 1-4) Humans Aedes aegypti et al Tropical and subtropical coasts Nil-10%*
Omsk Togavirus Musk rat Ticks Siberia 2%
Crimean-Congo Bunyavirus Ixodes tick Ixodes tick Africa, Asia, Eastern Europe 15-70%
Bolivian and Argentinian Arenavirus (Machupa and Junin) Rodents (Calomys spp.) Urine South America ?
Haemorrhagic fever with renal syndrome Hantavirus Rodents Faeces Northern Asia, northern Europe 30%
"Mortality of uncomplicated and haemorrhagic dengue fever, respectively.

rhagic fever . Case mortality is high, but mild and subclinical infections also occur.

The virus may be isolated, or antigen-detected, in maximum security laboratories from serum, pharynx, pleural exudate and urine, but diagnosis will usually be established from *paired sera', the later specimen being taken 6-8 weeks after the onset of infection. The diagnosis should be considered in the UK and other non-endemic areas in patients presenting with fever within 21 days of leaving West Africa, particularly if they have organ failure or haemorrhagic features (although most patients initially suspected of having viral haemorrhagic fevers in the UK turn out to have malaria).


Strict isolation and general supportive measures, preferably in a special unit, are required. Tribavirin (ribavirin) is given intravenously (100 mg/kg, then 25 mg/kg daily for 3 days and 12.5 mg/kg daily for 4 days).


The administration of convalescent immune plasma has been followed by recovery and is therefore recommended for prophylaxis after accidental exposure to infection.

Concepts of infection
Major manifestations of infection
Principles of management of infection
Diseases due to viruses
DNA viruses
Diseases due to chlamydiae
Diseases due to rickettsiae
Diseases due to bacteria
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Diseases due to spirochaetes
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