Japanese Encephalitis Virus (JEV)

Japanese Encephalitis Virus (JEV) is a flavivirus that causes Japanese encephalitis (JE), a serious and potentially fatal disease. JE is a leading cause of vaccine-preventable encephalitis in Asia, with an estimated 68,000 cases reported annually.

What is JEV?

JEV is a zoonotic virus, meaning it can be transmitted between animals and humans. The virus is primarily maintained in a cycle involving mosquitoes and vertebrate hosts, such as pigs and birds. Humans become infected when bitten by an infected mosquito.

Symptoms of JEV

The symptoms of JE can range from mild to severe and may include:

• Fever
• Headache
• Vomiting
• Confusion
• Seizures
• Coma
• Paralysis
• Respiratory failure

In severe cases, JE can cause:

• Encephalitis (inflammation of the brain)
• Meningitis (inflammation of the membranes surrounding the brain and spinal cord)
• Acute flaccid paralysis

Treatments for JEV

There is no specific antiviral treatment for JE, but supportive care can help manage symptoms and prevent complications. Treatment may include:

• Hospitalization to monitor and manage symptoms
• Fluid replacement and management of electrolyte imbalances
• Anticonvulsant medications to control seizures
• Respiratory support, such as oxygen therapy or mechanical ventilation
• Pain management and sedation

Prevention and Vaccination

The most effective way to prevent JE is through vaccination. There are several vaccines available, including:

• Inactivated JE vaccine (e.g., IXIARO)
• Live attenuated JE vaccine (e.g., SA14-14-2)
• Chimeric JE vaccine (e.g., IMOJEV)

Vaccination is recommended for:

• Travelers to areas where JE is common, such as rural Asia
• People who work with animals or in laboratories where JEV is handled
• Individuals who live in areas where JE is endemic

Transmission and Epidemiology

JEV is primarily transmitted through the bite of an infected mosquito, typically the Culex tritaeniorhynchus species. The virus can also be spread through:

• Vertical transmission (from mother to child during pregnancy or childbirth)
• Organ transplantation
• Lab exposure

JE is most commonly found in rural areas of Asia, particularly in:

• China
• India
• Japan
• Korea
• Southeast Asia (e.g., Thailand, Vietnam, Cambodia)

Diagnosis and Laboratory Testing

Diagnosis of JE is typically made through a combination of clinical evaluation, laboratory testing, and epidemiological investigation. Laboratory tests may include:

• Serology (e.g., ELISA, IgM capture ELISA)
• Virus isolation
• Reverse transcription polymerase chain reaction (RT-PCR)
• Immunohistochemistry