Choriomeningitis lymphocytic A98.5

The viral infection with the LCM virus usually causes an influenza-like disease or aseptic meningitis, sometimes with exanthema, arthritis, orchitis, parotitis or encephalitis.

The lymphocytic choriomeningitis virus, an arena virus (LCM virus), is spread worldwide (not in Australia). LCMV serve mice as the main host. The rodents themselves do not contract the disease, but excrete the pathogen throughout their lives via faeces, urine and nasal secretions. They are therefore relevant as sources of infection for humans. The percentage of infected house mice in a population can vary depending on geographical location. It is estimated that 5% of house mice in the USA carry LCMV, and other rodents such as toy hamsters (Syrian golden hamster) can also be a source of infection.

Human infection occurs through exposure to dust or food contaminated by the gray house mouse or hamster. If transmitted by mice, the disease occurs mainly in adults in autumn and winter.

In humans, infection with LCMV (especially in autumn and winter) is usually mild and influenza-like and is therefore also underdiagnosed (Bonthius DJ 2012, Kinori M et al. 2018)

General symptoms are: fever (38,5-40° C) possibly accompanied by rigor, feeling of illness and weakness, myalgia (especially lumbar), retroorbital headache, photophobia, anorexia, nausea and dizziness. Sore throats and dysesthesias are less frequent.

After 5 days up to 3 weeks the clinical condition of the patients may improve for 1-2 days. There are frequent relapses with recurrent fever, headache, exanthema, swelling of metacarpophalangeal and proximal interphalangeal joints, signs of meningitis, painful orchitis, parotitis or alopecia of the scalp.

Neurological symptoms (Bonthius DJ 2012): A small number of patients develop aseptic meningitis. In rare cases, encephalitis, ascending paralysis, bulbar paralysis, transverse myelitis or other neurological symptoms may occur. Neurological sequelae are rare in patients with meningitis, but can occur in encephalitis in up to 33% of patients.

In the early stages of the disease, the pathogen can be cultured from blood and cerebrospinal fluid in the baby mouse.

The diagnosis of LCMV infection is made by isolating the pathogen, detecting its nucleic acids by PCR or by detecting specific antibodies using the early positive IFTA or the indirect immunofluorescence test, ELISA or neutralisation test.

During the first trimester of pregnancy, infection with LCMV can cause abortion. In the second and third trimesters, infection of the fetus leads to death intrauterine or soon after birth, in live-born children to hydrocephalus, microcephaly chorioretinitis and mental retardation (Delaine M et al.2017).

Symptomatic. The measures depend on the severity of the disease. If aseptic meningitis, encephalitis or meningoencephalitis develops, patients should be admitted to hospital. Treatment with ribavirin may be considered, but has proven ineffective in many cases. Alternatively, favipiravir can be used as "first-line therapy" (Hickerson BT et al. 2018).

Pregnant women should avoid any contact with mice, golden hamsters and other rodents. This pathogen, which is not without danger, is usually not considered because of its relative rarity (Kinori M et al. 2018).

Case studies (cited and reported in Enders G et al. 1999):

The authors describe 6 virologically confirmed congenital LCMV infections that occurred in different parts of western Germany between 1991 and 1997. Observed were hydrocephalus and intrauterine death at the 22nd week of pregnancy, hydrocephalus internus (diagnosed in the second trimester), postpartum chorioretinitis, dumbness, cramps, inability to sit and swallow.

In addition, twins delivered by caesarean section showed dystrophy, hydrocephalus, microcephalus, chorioretinitis, cramps, delayed psychomotor development and blindness.

One infant 3 months after birth was temporarily ill with meningitis and conjunctivitis without hydrocephalus or chorioretinitis, and in one case hydrocephalus, microcephalus, intracranial calcifications and chorioretinitis were observed. The child was nearly blind. Five months after birth a congenital infection of other etiology was suspected and confirmed as LCMV infection at the age of nine months.

In 2 cases an exposure to Syrian golden hamster, in one case to house mice during pregnancy could be determined. 3 cases could be followed prospectively. The aetiology of the others was detected after birth. A hydrocephalus in the fetus and in the newborn additionally a chorioretinitis should induce to look for an etiology of LCMV besides other congenital infections.

1. Bonthius DJ (2012) Lymphocytic choriomeningitis virus: an underrecognized cause of neurologic disease in the fetus, child, and adult. Semin Pediatrics Neurol 19(:89-95.
2. Delaine M et al (2017) Microcephaly Caused by Lymphocytic Choriomeningitis Virus. Emerg Infect Dis 23:1548-1550.
3. Enders G et al (1999) Congenital lymphocytic choriomeningitis virus infection: an underdiagnosed disease. Pediatric Infect Dis J 18: 652-655.
4. Hickerson BT et al (2018) Effective Treatment of Experimental Lymphocytic Choriomeningitis Virus Infection: Consideration of Favipiravir for Use With Infected Organ Transplant Recipients. J Infect Dis 218:522-527.
5. Kinori M et al (2018) Congenital lymphocytic choriomeningitis virus-an underdiagnosed fetal teratogen. J AAPOS 22:79-81.
6. Souders HT et al.2015) Protracted symptoms in lymphocytic choriomeningitis: a case report. J Child Neurol 30:644-647.