x | x |
Today is | |
IMMUNOLOGY
|
Lymphocytic choriomeningitis
deaths from an Arenavirus infection In May 2005, the Rhode Island and Massachusetts Departments of Health and CDC reported three deaths from an lymphocytic choriomeningitis virus (LCMV) infection. LCMV is an arenavirus. The deaths were in organ transplant recipients. It appears that the originally infected person obtained the virus from the urine or feces of house mice or a pet hamster. A recently purchased pet hamster owned by that person was found to be infected with LCMV. This person died of unrelated causes and donated organs were used for transplant in four recipients in April 2005. All four developed similar symptoms and tested positive for LCMV. Three died. This is the second time that LCMV has been known to be transmitted via organ transplantation. Lymphocytic choriomeningitis usually only has a fatality rate of 1% and most patients clear the virus and recover completely. It is likely that the transplant patients died because immuno-suppressive drugs are used to counter organ rejection and therefore they could not mount an immune response to the virus.
|
|
The following comes from CDC Lymphocytic choriomeningitis Lymphocytic 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 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, infection without symptoms or mild febrile illnesses are common clinical manifestations. Additionally, pregnancy-related infection has been associated with congenital hydrocephalus, chorioretinitis, and mental retardation. Host The primary host is the common house mouse,
Mus musculus. Infection in house mouse populations may vary by
geographic location but, about 5% of mice throughout the United States carry
LCMV. The virus is found in the saliva, urine, and feces of infected mice.
Infected mice carry LCMV and shed it for the duration of their lives without
showing any sign of illness. Other types of rodents, such as hamsters, are
not the natural reservoirs but can become infected with LCMV from wild mice
at the breeder, in the pet store or home environment. Humans are more likely
to contract LCMV from house mice, but infections from pet rodents have also
been reported. Individuals become infected with LCMV after exposure to fresh urine, droppings, saliva, or nesting materials. Transmission can also occur when these materials are directly introduced into broken skin, the nose, the eyes, or the mouth, or presumably, via the bite of an infected rodent. Person-to-person transmission has not been reported, with the exception of vertical transmission from infected mother to fetus. Recent investigations indicate that organ transplantation may also be a means of transmission. Epidemiology 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 5%. Symptoms Some people infected with LCMV do not become
ill. For infected persons who do become ill, onset of symptoms usually
occurs 8-13 days after being exposed to the virus. 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, lack of appetite, 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 recovery, 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 (increased
fluid on the brain), 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. 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 of illness, 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 permanent. Aseptic meningitis, encephalitis, or
meningoencephalitis requires hospitalization and supportive treatment based
on severity. 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 routine use for treatment of LCM in humans. 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 work with the virus or 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 that have become contaminated with
LCMV, or if the animals become infected from other wild mice. Human fetuses
are at risk of acquiring infection vertically from an infected mother. |
Prevention
LCMV infection can be prevented by avoiding
contact with house mice and taking precautions when handling pet rodents
(i.e. mice, hamsters, or guinea pigs).
|
|
The above section comes from the CDC web site. For more information on LCMV go here | |
Return to the
rodent transmitted virus chapter Return to the Microbiology and Immunology On-line textbook
|