Summary about Disease
Japanese encephalitis (JE) is a mosquito-borne viral disease that primarily affects the central nervous system. It is a leading cause of viral encephalitis in Asia. The virus is maintained in a cycle involving mosquitoes and vertebrate hosts, mainly pigs and wading birds. Most JE virus infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections result in severe disease characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and ultimately death.
Symptoms
Most people infected with JE virus have mild or no symptoms. When symptoms do occur, they may include:
Fever
Headache
Vomiting
Confusion
Seizures
Paralysis (weakness or inability to move parts of the body)
Neck stiffness
Coma
Causes
JE is caused by the Japanese encephalitis virus (JEV). The virus is transmitted to humans through the bite of infected mosquitoes, primarily Culex species. The mosquitoes become infected by feeding on infected animals, such as pigs and wading birds. JE is not transmitted from person to person.
Medicine Used
There is no specific antiviral treatment for JE. Treatment focuses on supportive care to manage symptoms and complications. This may include:
Hospitalization
Ventilatory support (breathing machine)
IV fluids
Medications to control seizures
Management of secondary infections
Is Communicable
No, Japanese encephalitis is not communicable from person to person. It is transmitted through the bite of infected mosquitoes.
Precautions
Prevention focuses on avoiding mosquito bites:
Use insect repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone.
Wear long-sleeved shirts and pants.
Stay in air-conditioned or screened rooms.
Use mosquito nets when sleeping outdoors or in unscreened rooms.
Reduce mosquito breeding grounds by emptying standing water in containers.
Vaccination: A safe and effective JE vaccine is available and recommended for people living in or traveling to areas where JE is common.
How long does an outbreak last?
The duration of a Japanese encephalitis outbreak can vary. It typically coincides with the mosquito season, which is influenced by rainfall and temperature. Outbreaks can last for several weeks to months, depending on environmental conditions and mosquito control measures.
How is it diagnosed?
Diagnosis is typically made based on:
Clinical symptoms
Laboratory testing: Testing of blood or cerebrospinal fluid (CSF) to detect JE virus-specific antibodies or the virus itself. Common tests include ELISA, PCR, and virus neutralization tests.
Neuroimaging: MRI or CT scans may be used to assess brain inflammation or damage.
Timeline of Symptoms
The incubation period (time from infection to symptom onset) is typically 5-15 days.
Initial Phase: Fever, headache, and vomiting may develop.
Progression: Over the next few days, neurological symptoms may appear, including confusion, disorientation, seizures, paralysis, and coma.
Recovery: If the patient survives, recovery can be slow and may involve long-term neurological sequelae (e.g., paralysis, cognitive deficits).
Important Considerations
JE is a serious disease with a high mortality rate (up to 30%) among those who develop encephalitis.
Neurological sequelae are common among survivors.
Vaccination is the most effective way to prevent JE.
Travelers to endemic areas should consult with their healthcare provider about vaccination and mosquito bite prevention measures.
Public health efforts to control mosquito populations are important for preventing JE outbreaks.