Lymphocytic choriomeningitis

Lymphocytic choriomeningitis (LCM), is a rodent-borne viral infectious disease that presents as aseptic meningitis, encephalitis or meningoencephalitis. Its causative agent is the Lymphocytic Choriomeningitis Virus (LCMV), a member of the family Arenaviridae. The name was coined by Charles Armstrong in 1934.^[1]

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Alternative Names

• Benign lymphocytic meningitis
• Lymphocytic meningoencephalitis
• Serous lymphocytic meningitis
• La Maladie d'Armstrong ^[2]

Virus biology

LCMV is an enveloped virus with a helical nucleocapsid, it has a negative-sense, single-stranded, non-segmented, RNA genome. The first arenavirus, lymphocytic choriomeningitis virus (LCMV), was isolated in 1933 by Charles Armstrong during a study of an epidemic in St. Louis . Although not the cause of the outbreak, LCMV was found to be a cause of nonbacterial or aseptic meningitis.

Infection

LCMV is naturally spread by the common house mouse, Mus musculus.^[3] Once infected, these mice can become chronically infected by maintaining virus in their blood and/or persistently shedding virus in their urine. Chronically infected female mice usually transmit infection to their offspring, which in turn become chronically infected. About five per cent of mice, hamsters and rodents are thought to carry the disease. Pet rodents can contract the virus after exposure to infected mice.

The virus seems to be relatively resistant to drying and therefore humans can become infected by inhaling infectious aerosolized particles of rodent urine, feces, or saliva, by ingesting food contaminated with virus, by contamination of mucus membranes with infected body fluids, or by directly exposing cuts or other open wounds to virus-infected blood. The only documented cases of transmission from animals, have occurred between humans and mice or hamsters. However, humans rarely become infected from pet rodents.

Seroprevalence is approximately 5% of the US population. It tends to be more common among lower socio-economic groupings, probably reflecting more frequent and direct contacts with mice.

The virus normally has little effect on healthy people but can be deadly for people whose immune system has been weakened. Person-to-person transmission does not usually occur, with the exception of vertical transmission from an infected mother to fetus. In May 2005, reports of the deaths of at least six organ transplant patients in the US were linked to the virus.

Trivia

• The virus plays a role in the modern remake of the television series Battlestar Galactica. In the episode entitled "Torn", the Cylon race is exposed to "lymphocytic encephalitis" after they bring an ancient beacon carrying the pathogen aboard their craft. Unlike their human counterparts, the Cylons do not have a natural immunity to this virus; many die. The humans learn of this weakness in the episode entitled "A Measure of Salvation".

References

• Centers for Disease Control and Prevention. Lymphocytic Choriomeningitis Fact Sheet
• CBWInfo (1999). Safety Precautions for Lymphocytic Choriomeningitis Casualties. Retrieved on 2006-05-11.
• Associated Press. "Rodent virus now linked to six deaths - PetSmart in Rhode Island testing animals for rare disease", MSNBC, Microsoft, 25 May, 2005. Retrieved on 2006-05-11. 
• AAP. "Australian scientists discover new virus", The Age, Fairfax, 22 April, 2007. Retrieved on 2007-04-22.