Japanese Encephalitis
Japanese encephalitis is the most commonly diagnosed epidemic encephalitis in the world.
This is an infection of the brain caused by Japanese encephalitis virus which is a flavivirus related to dengue, yellow fever and West Nile virus and is spread by a bite of a mosquito named Culex tritaeniorhynchus.
This mosquito is night time biting and thrives in the ricefields, marshes and shallow pools of water. Those at risk of JE are the following:
1. Asians
2. Pig rearing areas
3. Rice farms
4. In high rainfall/ flooding areas
The incubation period of JE is 5-15 days and some will resolve in a few days or some will remain unwell and have neurologic deficits.
This disease affects both the children and adults. Clinically, the patient will manifest the following symptoms:
1. Headache
2. Convulsions
3. Vomiting
4. Diarrhea
5. Changes in mental status
6. Changes in motor functions
7. Seizures
The Acute encephalitis syndrome standard case definition refers to a person of any age with acute onset of fever and at least one of the following:
– change in mental status like confusions, disorientation and coma
– new onset of seizure
– neck stiffness/ meningeal signs
Thirty per cent of affected individuals will develop severe disease with permanent neurologic problems. The neurologic manifestations could be:
1. Acute encephalitis
– most recognized
2. Parkinsonian syndromes
– characteristic of JE
3. Poliomyelitis like acute flaccid paralysis
Affected patients considered to have poor prognosis are those who are showing the following:
– deep obtundation
– multiple prolonged seizures
– flexor/ extensor posturing
– abnormal respiratory patterns
– abnormal pupillary reflexes
Thirty per cent of those with severe symptoms will die. So, Japanese encephalitis infection is considered by the World Health Organization as a public health issue and that all are encourage to be vaccinated against the Japanese Encephalitis infection.