Machupo virus

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Group: Group V ((-)ssRNA); Family: Arenaviridae; Genus: Arenavirus; Species: Machupo Virus

Arenavirus Machupo Virus

Description and Significance

Machupo virus is a virus from the Arenaviridae family and is the cause of Bolivian hemorrhagic fever (BHF), also known as Black Typhus or Ordog Fever. It was first identified in 1959 by a research group from the National Institutes of Health, led by Karl Johnson. Like some of the other New World Arenaviruses, infection by Machupo virus causes hemorragic fever syndromes and is spread by rodents. [1]

Structure, Metabolism, and Life Cycle

Machupo Virus is a spherical and pleomorphic virus, with a diameter ranging from 50 to 300 nm in length (average of 120nm). It has a single-stranded and bi-segmented RNA genome, and the virus contains ribosomes that give it a sandy appearance under electron microscopy. The virus is enclosed in a dense, lipid-containing envelope with 8-10 nm long club-shaped projections around the outside. [1] [2]

Interesting features of its structure; how it gains energy (how it replicates, if virus); what important molecules it produces (if any), does it have an interesting life cycle?

Ecology and Pathogenesis

Machupo virus is primarily spread through the aerosol transmission of dust particles from the urine, saliva, or feces of infected rodents. Other methods of transmission include food-borne and direct contact with virus particles. The vesper mouse, Calomys callosus, is the reservoir for the virus and is native to Bolivia and the surrounding areas. This specificity in rodent hosts limits the prevalence of the Machupo virus and keeps the occurrence of the virus concentrated in Bolivia and the areas surrounding it. Ticks and mosquitoes are also susceptible to infection by the virus and are the main vectors for dissemination. [3] The incubation period for the virus is between four and twenty one days, and it is capable of surviving in blood specimens outside of the host for up to two weeks. Some initial symptoms caused by infection of the virus include fever, mild hypertension, headache, bleeding gums, and fatigue. Advanced symptoms include mucous membrane haemorrhage, epistaxis, melena, and neurological damage such as tremors, seizures, loss of muscle control, and coma. Symptoms usually arise after a one week incubation period and generally last for one week. The fatality rate for the virus is between 18% and 22%, and death can occur between a few hours and a few days after symptoms begin. [4] Machupo virus requires Biosafety Level Four conditions when it is being worked with. The chemical and biological weapons programs for both the United States and the Soviet Union researched the Machupo virus as a potential biological weapon before being shut down. [5]

Natural habitat (soil, water, commensal of humans or animals?)
If relevant, how does this organism cause disease? Human, animal, or plant hosts? Important virulence factors, as well as patient symptoms.


[1] Public Health Agency of Canada: Machupo Virus Pathogen Safety Data Sheet,, Date Modified: 2011-02-18.

[2] F.A. Murphy et al. (1969, October). Morphological Comparison of Machupo with Lymphocytic Choriomeningitis Virus: Basis for New Taxonomic Group, Journal of Virology 4(4), pp 535-541. Retrieved from

[3]"Machupo". Retrieved from on 2013-07-21.

[4] Center for Food Security & Public Health and Institute for International Cooperation in Animal Biologics, Iowa State University: Viral Hemorrhagic Fevers Caused by Arenaviruses,, last updated: February 23, 2010.

[5]"Chemical and Biological Weapons: Possession and Programs Past and Present", James Martin Center for Nonproliferation Studies, Middlebury College, April 9, 2002.


Page authored by Shane Sontag, student of Mandy Brosnahan, Instructor at the University of Minnesota-Twin Cities, MICB 3301/3303: Biology of Microorganisms.