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Article title: Lymphocytic Choriomeningitis: DVRD
Conditions: Lymphocytic Choriomeningitis
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What is lymphocytic choriomeningitis?
choriomeningitis, or LCM, is a rodent-borne viral infectious disease that
presents as aseptic meningitis (inflammation of the membrane, or meninges,
that surrounds the brain and spinal cord), encephalitis (inflammation of
the brain), or meningoencephalitis (inflammation of both the brain and
meninges). Its causative agent is the lymphocytic choriomeningitis virus (LCMV),
a member of the family Arenaviridae, that was initially isolated in 1933.
Although LCMV is most commonly recognized as causing neurological disease,
as its name implies, asymptomatic infection or mild febrile illnesses are
common clinical manifestations. Additionally, pregnancy-related infection
has been associated with abortion, congenital hydrocephalus and
chorioretinitis, and mental retardation.
Where is the disease found?
LCM and milder LCMV
infections have been reported in Europe, the Americas, Australia, and
Japan, and may occur wherever infected rodent hosts of the virus are
found. However, the disease has historically been underreported, often
making it difficult to determine incidence rates or estimates of
prevalence by geographic region. Several serologic studies conducted in
urban areas have shown that the prevalence of LCMV infection among humans
ranges from 2% to 10%.
How is LCMV spread, and how do humans become infected?
LCMV is naturally spread by the common house mouse, Mus musculus. Once infected, these mice can become chronically infected by maintaining virus in their blood and/or persistently shedding virus in their urine, a common characteristic of other arenavirus infections in rodents. Chronically infected female mice usually transmit infection to their offspring, which in turn become chronically infected.
Humans 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. LCMV infection has also been
documented among staff handling infected hamsters. Person-to-person
transmission has not been reported, with the exception of vertical
transmission from an infected mother to fetus.
What are the symptoms of LCM?
The incubation period of LCMV infection is usually between 8 and 13 days. A characteristic biphasic febrile illness then follows. The initial phase, which may last as long as a week, typically begins with any or all of the following symptoms: fever, malaise, anorexia, muscle aches, headache, nausea, and vomiting. Other symptoms that appear less frequently include sore throat, cough, joint pain, chest pain, testicular pain, and parotid (salivary gland) pain. Following a few days of remission, the second phase of the disease occurs, consisting of symptoms of meningitis (for example, fever, headache, and a stiff neck) or characteristics of encephalitis (for example, drowsiness, confusion, sensory disturbances, and/or motor abnormalities, such as paralysis). LCMV has also been known to cause acute hydrocephalus, which often requires surgical shunting to relieve increased intracranial pressure. In rare instances, infection results in myelitis (inflammation of the spinal cord) and presents with symptoms such as muscle weakness, paralysis, or changes in body sensation. An association between LCMV infection and myocarditis (inflammation of the heart muscles) has been suggested.
During the first phase of
the disease, the most common laboratory abnormalities are a low white
blood cell count (leukopenia) and a low platelet count (thrombocytopenia).
Liver enzymes in the serum may also be mildly elevated. After the onset of
neurological disease during the second phase, an increase in protein
levels, an increase in the number of white blood cells or a decrease in
the glucose levels in the cerebrospinal fluid (CSF) is usually found.
Are there any complications after recovery?
Previous observations have
shown that most patients who develop aseptic meningitis or encephalitis
due to LCMV recover completely. No chronic infection has been described in
humans, and after the acute phase the virus is cleared. However, as in all
infections of the central nervous system, particularly encephalitis,
temporary or permanent neurological damage is possible. Nerve deafness and
arthritis have been reported. Infection of the human fetus during the
early states of pregnancy may lead to developmental deficits that are
Is the disease ever fatal?
LCM is usually not fatal. In general, mortality is less than 1%.
How is LCM treated?
Aseptic meningitis, encephalitis, or meningoencephalitis requires hospitalization and supportive treatment based on severity. There is no specific drug therapy for LCM. Anti-inflammatory drugs, such as corticosteroids, may be considered under specific circumstances. Although studies have shown that ribavirin, a drug used to treat several other viral diseases, is effective against LCMV in vitro, there is no established evidence to support its use for treatment of LCM in humans.
Who is at risk for LCMV infection?
Individuals of all ages who
come into contact with urine, feces, saliva, or blood of the house mouse
are potentially at risk for infection. Laboratory workers who themselves
handle infected animals are also at risk. However, this risk can be
minimized by utilizing animals from sources that regularly test for the
virus, wearing proper protective laboratory gear, and following
appropriate safety precautions. Owners of pet mice or hamsters may be at
risk for infection if these animals originate from colonies with
circulating LCMV, or if the animals become infected from other wild mice.
Human fetuses are at risk of acquiring infection vertically from infected
How can LCMV infections be prevented?
Like many other rodent-borne infectious diseases, LCMV infection can be prevented by avoiding or minimizing direct physical contact with rodents or exposure to their excreta. Adequate ventilation should be provided to any heavily infested, previously unventilated enclosed room or dwelling prior to cleanup. A liquid disinfectant, such as a diluted household bleach solution, should be applied to visible rodent droppings and their immediate surroundings. Gloves should be worn when disinfecting and cleaning up rodent excreta. Rodent spring traps may be set up in households or dwellings where rodent infestations are a concern.
What needs to be done to address the threat of LCMV?
distributions of the rodent hosts are widespread both domestically and
abroad. However, infrequent recognition and diagnosis, and therefore
underreporting, of LCM, have limited scientistsí ability to estimate
incidence rates and prevalence of disease among humans. Understanding the
epidemiology of LCM and LCMV infections will help to further delineate
risk factors for infection and develop effective preventive strategies.
Increasing physician awareness will improve disease recognition and
reporting, which may lead to better characterization of the natural
history and the underlying immunopathological mechanisms of disease, and
stimulate future therapeutic research and development.
Jahrling PB, Peters CJ. Lymphocytic choriomeningitis virus: a neglected pathogen of man. Arch Pathol Lab Med 1992;116:486-8.
Peters CJ, Buchmeier M, Rollin PE, Ksiazek TG. Arenaviruses. In: Belshe RB, ed. Textbook of
Human Virology. 2nd ed. St. Louis: Mosby-Year Book, Inc. 1991:541-70.
Peters CJ, et al. Arenaviridae: Biology of viruses. In: Fields BN, Knipe DM, Howley PM, et al,
eds. Fields Virology. 3rd ed. Philadelphia: Lippincott-Raven Publishers. 1996:1527-51.
Peters CJ. Arenaviruses. In: Richman DD, Whitley RJ, Hayden FG, eds. Clinical Virology.
New York: Churchill Livingstone, Inc. 1997: 973-96.
Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases
Centers for Disease Control and Prevention
Public Health Service, U.S. Department of Health and Human Services
August 23, 2000
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