Lymphocytic choriomeningitis virus is endemic in rodents. Human infection results most commonly from exposure to dust or food contaminated by the gray house mouse or hamsters, which harbor the virus and excrete it in urine, feces, semen, and nasal secretions. The percentage of infected house mice in a population may vary by geographic location; it is estimated that 5% of house mice throughout the US carry lymphocytic choriomeningitis virus and can transmit the virus throughout their life without showing any sign of illness. When transmitted by mice, the disease occurs primarily in adults during autumn and winter.
The incubation period for lymphocytic choriomeningitis is 1 to 2 weeks.
Most patients have no or minimal symptoms. Some develop a flu-like illness. Fever, usually 38.5 to 40° C, with rigors is accompanied by malaise, weakness, myalgia (especially lumbar), retro-orbital headache, photophobia, anorexia, nausea, and light-headedness. Sore throat and dysesthesia occur less often.
After 5 days to 3 weeks, patients may improve for 1 or 2 days. Many relapse with recurrent fever, headache, rashes, swelling of metacarpophalangeal and proximal interphalangeal joints, meningeal signs, orchitis, parotitis, or alopecia of the scalp.
Aseptic meningitis occurs in a minority of patients. Rarely, frank encephalitis, ascending paralysis, bulbar paralysis, transverse myelitis, or other neurologic symptoms can occur. Neurologic sequelae are rare in patients with meningitis but occur in up to 33% of patients with encephalitis.
Infection during pregnancy may cause fetal abnormalities, including hydrocephalus, chorioretinitis, and intellectual disability. Infections that occur during the 1st trimester may result in fetal death.
Lymphocytic choriomeningitis is suspected in patients with exposure to rodents and an acute illness, particularly aseptic meningitis or encephalitis. Aseptic meningitis may lower cerebrospinal fluid glucose mildly but occasionally to as low as 15 mg/dL (0.83 mmol/L). Cerebrospinal fluid white blood cell counts range from a few hundred to a few thousand cells, usually with > 80% lymphocytes. White blood cell counts of 2000 to 3000/mcL (2 to 3 x 109/L) and platelet counts of 50,000 to 100,000/mcL (50 to 100 x 109/L) typically occur during the first week of illness.
Diagnosis can be made by
Treatment of lymphocytic choriomeningitis is supportive. Measures needed depend on the severity of the illness. If aseptic meningitis, encephalitis, or meningoencephalitis develops, patients should be hospitalized, and treatment with ribavirin can be considered.
Anti-inflammatory drugs (eg, corticosteroids) may be considered in certain circumstances.
In humans, lymphocytic choriomeningitis is usually acquired via exposure to dust or consumption of food contaminated by mouse or hamster excreta.
Most patients have no or minimal symptoms, but some develop a flu-like illness, and a few develop aseptic meningitis.
Infection during pregnancy may cause fetal abnormalities; if infection occurs during the 1st trimester, the fetus may die.