JAPANESE ENCEPHALITIS

A disease caused by the mosquito-borne Japanese encephalitis virus (JEV).
The virus itself is from the family Flaviviridae.
Reservoirs of the virus: Domestic pigs, wild birds (especially herons) and transmission to humans may cause severe symptoms; no person to person transmission.
- Most important disease vectors: mosquitoes (Culex tritaeniorhynchus, Culex vishnui).
Most prevalent in Southeast Asia and East Asia.
Other name: Japanese B encephalitis

5 to 15 day incubation period; most infections are asymptomatic.
- Encephalitis in 1 in 250 infections.
In humans, symptoms may include:
- Severe rigors – marking onset of disease.
- Fever, headache and malaise – non-specific.
  - May last for 1 and 6 days.
- During acute encephalitic stage:
  - neck rigidity, cachexia, hemiparesis, convulsions, elevated body temperature between 38–41 °C, mental retardation.
- In persons with CNS involvement:
  - deafness, emotional lability, hemiparesis.

Increased activation of microglia following infection influences disease outcome.
In animals, important signs are:
- infertility and abortion –pigs
- neurological disease – horses
- systemic signs:
  - fever, lethargy and anorexia

DIAGNOSIS

Physician may do/request:
- History & Physical Exam
- Laboratory tests:
  - IgM capture ELISA
  - Indirect fluorescent antibody staining

RECOMMENDED MEDICATIONS

Primarily supportive treatment; no specific treatment for the disease.
- Feeding assistance, breathing or seizure control whenever necessary.
- Mannitol – for increased intracranial pressure.

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