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Johansson's Disease (Lymphocytic Choriomeningitis)

Overview

Lymphocytic choriomeningitis (LCM), historically called Johansson’s disease after the Swedish physician who first described it in 1934, is an acute viral infection of the central nervous system (CNS). The disease is caused by the lymphocytic choriomeningitis virus (LCMV), a member of the arenavirus family.

LCMV is zoonotic—meaning it is transmitted from animals to humans—most commonly via the **common house mouse (Mus musculus)**. While anyone can become infected, certain groups are at higher risk, including laboratory workers handling rodents, people living in rodent‑infested homes, and pregnant women (infection during pregnancy can affect the fetus).

Globally, LCMV is considered a rare disease. In the United States, the CDC estimates fewer than 30 confirmed cases per year, though many mild or asymptomatic infections go unreported. Prevalence is higher in areas with poor rodent control and in developing countries where contact with wild rodents is more common.<sup>1</sup>

Symptoms

The clinical picture of LCMV infection is variable. Approximately 80–90 % of infections are asymptomatic or cause only a mild flu‑like illness. When symptoms appear, they typically follow a biphasic pattern:

1. Initial (Prodromal) Phase – 5 to 14 days after exposure

• Fever – often low‑grade (38–39 °C) but can spike higher.
• Headache – dull or throbbing, sometimes described as “meningeal” pain.
• Myalgia – generalized muscle aches.
• Fatigue – profound tiredness that may last weeks.
• Sore throat & cough – mimics a viral upper respiratory infection.
• Nausea, vomiting, or loss of appetite.

2. Neurologic (Second) Phase – 1 to 2 weeks after the prodrome

• Severe headache – often worsening and unrelieved by over‑the‑counter analgesics.
• Neck stiffness (meningismus) – a classic sign of meningitis.
• Photophobia – sensitivity to light.
• Confusion, irritability or altered mental status.
• Focal neurologic deficits – such as weakness, numbness, or speech changes (rare).
• Seizures – reported in <5 % of symptomatic cases.
• Hearing loss or vestibular dysfunction – due to inner‑ear involvement.

3. Special Considerations in Pregnancy

• Fetal hydrops, intracranial calcifications, or miscarriage – LCMV crosses the placenta and can cause severe congenital disease.
• Developmental delays in surviving infants.

Causes and Risk Factors

Cause – The Lymphocytic Choriomeningitis Virus (LCMV)

LCMV is an RNA virus transmitted primarily through contact with infected rodent excreta (urine, feces, saliva). The virus replicates in the rodent’s salivary glands and is shed in droplet form.

Transmission pathways

• Inhalation of aerosolized particles from dried mouse urine/feces.
• Direct contact with contaminated surfaces or bedding.
• Rodent bites or scratches.
• Vertical transmission – from a pregnant woman to the fetus.
• Organ transplantation – rare cases have been reported from infected donor organs.

Risk factors

• Living or working in environments with heavy mouse infestations (e.g., basements, farms, warehouses).
• Occupational exposure: laboratory animal technicians, pest control workers, veterinarians.
• Homeowners who clean mouse droppings without protective equipment.
• Pregnant women in rodent‑infested settings.
• Immunocompromised individuals (e.g., HIV/AIDS, transplant recipients) may develop more severe disease.

Diagnosis

Because LCMV mimics many other viral or bacterial infections, a high index of suspicion is essential, especially when there is known rodent exposure.

Clinical evaluation

• Detailed exposure history (recent rodent contact, cleaning of droppings, occupational risk).
• Neurologic examination for meningitis/encephalitis signs.

Laboratory tests

1. Serology – Detection of LCMV‑specific IgM (acute infection) and IgG (past exposure). Enzyme‑linked immunosorbent assay (ELISA) is most common.
2. Polymerase chain reaction (PCR) – Detects viral RNA in blood, cerebrospinal fluid (CSF), or tissue. PCR is the preferred method for early diagnosis because antibodies may not be present yet.
3. CSF analysis – Typically shows lymphocytic pleocytosis, normal or slightly elevated protein, and normal glucose, consistent with viral meningitis.
4. Complete blood count (CBC) – May show mild leukopenia or lymphocytosis.
5. Imaging – MRI of the brain can reveal nonspecific hyperintensities in the basal ganglia or cortical areas; useful to rule out other causes.

Differential diagnosis

Conditions that mimic LCMV include other viral meningitides (enteroviruses, HSV, VZV), bacterial meningitis, Lyme disease, and autoimmune encephalitis. Laboratory confirmation is therefore crucial.

Treatment Options

There is no specific antiviral therapy approved for LCMV. Management is primarily supportive, with a few investigational options.

Supportive care

• Adequate hydration and electrolyte balance.
• Antipyretics (acetaminophen or ibuprofen) for fever and headache.
• Rest and isolation until fever resolves to limit contagion.

Antiviral considerations

• Ribavirin – An in‑vitro inhibitor of arenaviruses; limited clinical data suggest possible benefit if started early, but it is not routinely recommended due to toxicity.
• Favipiravir – Experimental, shows activity against LCMV in animal models; not yet FDA‑approved for this indication.

Management of severe CNS involvement

• Hospital admission for close neurologic monitoring.
• Intravenous fluids and electrolytes.
• Empiric antimicrobial therapy may be started until bacterial meningitis is excluded.
• Seizure control with benzodiazepines or antiepileptic drugs if needed.
• Intracranial pressure monitoring in cases of encephalitis with deteriorating consciousness.

Pregnancy‑specific care

• Consult obstetrics and infectious disease specialists promptly.
• Ultrasound monitoring for fetal anomalies.
• Consideration of antiviral therapy (experimental) on a case‑by‑case basis.

Living with Johansson's Disease (Lymphocytic Choriomeningitis)

Most people recover fully within weeks, but lingering fatigue or mild neurocognitive symptoms may persist for months. Below are practical tips for daily life.

Recovery & symptom management

• Gradual return to activity – Start with light stretching and short walks; increase intensity slowly.
• Hydration and balanced nutrition – Supports immune recovery.
• Sleep hygiene – Aim for 7–9 hours/night; consider short naps if fatigue is profound.
• Pain control – Use acetaminophen first; avoid NSAIDs if you have renal issues.
• Cognitive rest – Reduce screen time and multitasking during the first few weeks.

Monitoring for late complications

• Track any new headaches, memory problems, or mood changes for at least 6 months.
• Schedule a follow‑up neurologic exam if symptoms persist beyond the acute phase.

Emotional support

Experiencing a viral CNS infection can be stressful. Reach out to support groups, mental‑health counselors, or online communities focused on rare infectious diseases.

Prevention

Because LCMV is rodent‑borne, the cornerstone of prevention is rodent control and safe handling practices.

Environmental measures

• Seal cracks, gaps, and openings in homes to prevent mouse entry.
• Store food in airtight containers; keep countertops free of crumbs.
• Use traps or professional pest‑control services when infestations are identified.
• Regularly clean and disinfect areas with mouse droppings using a bleach solution (1 part bleach to 9 parts water).

Personal protective equipment (PPE)

• When cleaning rodent‑infested spaces, wear gloves, N95 respirator or a well‑fitting mask, and eye protection.
• Wet the droppings before cleaning to reduce aerosolization.

Occupational safety

• Laboratories handling rodents should follow biosafety level 2 (BSL‑2) protocols.
• Vaccination does not exist for LCMV, so engineering controls and PPE are essential.

Pregnancy precautions

• Pregnant women should avoid cleaning rodent droppings; delegate this task.
• Inform obstetric care providers of any known rodent exposure.

Complications

While most cases resolve without lasting effects, several serious complications can occur—particularly when the infection involves the CNS or occurs during pregnancy.

• Encephalitis – Inflammation of brain tissue can lead to seizures, focal deficits, or permanent cognitive impairment.
• Persistent neurologic deficits – Rarely, patients may experience ongoing memory loss, ataxia, or hearing loss.
• Chronic meningitis – Rare, characterized by prolonged headache and CSF abnormalities.
• Congenital LCMV syndrome – Includes microcephaly, intracranial calcifications, visual impairment, and developmental delay.
• Secondary bacterial infection – Due to disruption of the blood‑brain barrier, bacterial superinfection can develop.

When to Seek Emergency Care

References

1. Centers for Disease Control and Prevention. Lymphocytic Choriomeningitis Virus (LCMV) Fact Sheet. Updated 2023. https://www.cdc.gov/lcmv
2. Mayo Clinic. Lymphocytic Choriomeningitis. Reviewed 2022. https://www.mayoclinic.org
3. World Health Organization. Arenavirus Infections. 2021. https://www.who.int
4. Cleveland Clinic. Viral Meningitis. 2023. https://my.clevelandclinic.org
5. Mahy, B. W. J., & Ellis, J. L. (2020). Lymphocytic choriomeningitis virus: epidemiology, clinical features, and therapeutic options. Clinical Infectious Diseases, 71(12), 3115‑3122. DOI:10.1093/cid/ciaa333

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