Japanese Encephalitis: Causes, Symptoms, Transmission, Treatment and Prevention

Japanese encephalitis is a potentially serious disease caused by a virus spread by infected mosquitoes in Asia and the western Pacific. The virus is the leading cause of vaccine-preventable encephalitis (inflammation of the brain). For most people traveling to Asia, the risk of contracting the virus is very low. Typically, people who live in areas where the disease is common or those who travel there for long periods are more likely to contract the virus.

The agent is related to the West Nile virus.

Mode of transmission

The Japanese encephalitis virus is transmitted through the bite of a mosquito. Transmission of the virus is common in rural, agricultural areas. In northern Asian regions, where the climate is temperate, the risk of infection is higher in summer and autumn. In tropical and subtropical regions, there is a higher risk throughout the year.

It is very rare for travelers visiting risk areas to be affected by Japanese encephalitis, but it is not excluded, especially in the case of a longer stay or if outdoor activities have been carried out.

Symptoms

Most people infected with the Japanese encephalitis virus have no symptoms or have mild, short-lived symptoms that are often mistaken for the flu.

Symptoms usually appear 5 to 15 days after being bitten by an infected mosquito. The most common symptoms consist of fever, chills, nausea and vomiting, and/or fatigue. Seizures are common, especially in children.

In the case of a severe infection, changes in mental status, motor disorders, confusion, and/or headache may occur.

A small percentage of infected people develop Japanese encephalitis (inflammation of the brain), signaled by the presence of cerebral edema and possible coma. In these cases, the risk of death and long-term neuropsychiatric sequelae increases significantly.

Diagnosis

The infection is usually diagnosed by measuring antibody levels using blood or spinal fluid samples.

Treatment

Currently, there are no specific medications available to treat Japanese encephalitis. Treatment focuses on relieving symptoms through rest, increased fluid intake, and the administration of analgesics and fever-reducing medications.

For some patients, hospitalization may be necessary for specialized care and close monitoring of the disease's progression.

Prevention

Japanese encephalitis can be prevented by avoiding mosquito bitesi. It is recommended to use insect repellents, wear long-sleeved shirts and long pants, and keep mosquito nets closed.

The Japanese encephalitis vaccine is recommended for people traveling to an endemic country, for long-term travelers (1 month or more), and for those who frequently travel to endemic areas.

There are a number of different vaccines. In Romania, the Ixiaro vaccine, which helps develop antibodies against the virus, is marketed and administered. Complete immunization occurs 28 days after the vaccine injection.

In most cases, 2 doses of the vaccine are required. The last dose should be administered at least 1 week before traveling. A booster dose (third dose) may be necessary for those who received the primary 2-dose vaccination series at least 1 year prior and who continue to be at risk of contracting the virus.

The vaccine against Japanese encephalitis is approved for people older than 2 months.

References
https://www.nfid.org/infectious-diseases/japanese-encephalitis/
https://www.nhs.uk/conditions/japanese-encephalitis/
https://www.romedic.ro/vaccinul-impotriva-encefalitei-japoneze-0P34492
http://srmv.ro/index.php/informatii-medicale/vaccinari/vaccinari-specifice-calatorului/item/238-encefalita-japoneza