Japanese Encephalitis (Viral infection affecting brain) : Symptoms, Causes, Diagnosis & Treatment

Japanese encephalitis (JE) virus is a single-stranded RNA virus that belongs to the genus Flavivirus and is closely related to West Nile and Saint Louis encephalitis viruses. JE virus is transmitted to humans through the bite of an infected mosquito, primarily Culex species. The virus is maintained in an enzootic cycle between mosquitoes and amplifying vertebrate hosts, primarily pigs and wading birds. Humans are incidental or dead-end hosts, because they usually do not develop a level or duration of viremia sufficient to infect mosquitoes.

JE virus is the most common vaccine-preventable cause of encephalitis in Asia, occurring throughout most of Asia and parts of the western Pacific

Self diagnosis – A person with Japanese encephalitis will probably have no symptoms at all, but if there are symptoms, they will appear 5 to 15 days after being infected. A person with mild Japanese encephalitis might only develop a fever and a headache, but in more severe cases, more serious symptoms can develop quickly.

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How does Japanese Encephalitis affect your body?

Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases symptoms may include headache, vomiting, fever, confusion, and seizures.

What are the Causes of Japanese Encephalitis?

Japanese encephalitis virus JEV is the most important cause of viral encephalitis in Asia. It is a mosquito-borne flavivirus, and belongs to the same genus as dengue, yellow fever and West Nile viruses.

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What are the Risk Factors of Japanese Encephalitis?

Common risk factors include :

  • Japanese Encephalitis occurs mostly in Southeast Asia.
  • Long-term travellers
  • Persons involved in outdoor recreational activities or on work assignments going to endemic areas are at risk, especially those visiting rural areas, farms, rice fields and irrigation areas.
  • Children under 15 years of age seem to particularly susceptible to the infection.
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What are the symptoms of Japanese Encephalitis?

The majority of cases are asymptomatic – persons do not exhibit symptoms. Those with symptoms usually get ill 5 to 15 days after exposure to the virus. Symptoms include

  • Fever
  • Severe headache
  • Vomiting
  • Diarrhea
  • General weakness

Some patients will develop neurological symptoms such as :

  • Tremors
  • Seizures (especially children)
  • Expressionless face
  • Sudden paralysis which can affect the respiratory system and cause bladder retention problems.
  • Patients may also experience behavioural changes which can be misdiagnosed as psychiatric illness.
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How is Japanese Encephalitis diagnosed?

Japanese encephalitis virus–specific immunoglobulin M (IgM) capture enzyme-linked immunoassay (ELISA) on serum or cerebrospinal fluid (CSF) is the standard diagnostic test for Japanese encephalitis. Virus isolation from clinical specimens is difficult because viremia in humans is transient and low level. Lumbar puncture is performed to obtain CSF and to rule out other potential etiologies of encephalitis. The opening pressure may be high, CSF protein level may be high, and CSF glucose level is often normal.

Potential bloodwork findings may include mild leukocytosis and hyponatremia.

MRI and CT scanning of the brain may show bilateral thalamic lesions with hemorrhage. Electroencephalography (EEG) may show diffuse slowing.

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How to prevent & control Japanese Encephalitis?

Tips to prevent Japanese encephalitis include :

  • Vaccination – Safe and effective JE vaccines are available to prevent disease. WHO recommends having strong JE prevention and control activities, including JE immunization in all regions where the disease is a recognized public health priority, along with strengthening surveillance and reporting mechanisms. There are 4 main types of JE vaccines currently in use: inactivated mouse brain-derived vaccines, inactivated Vero cell-derived vaccines, live attenuated vaccines, and live recombinant vaccines.
  • Use a repellent containing 20%-30% DEET or 20% Picaridin on exposed skin. Re-apply according to manufacturer’s directions.
  • Wear neutral-coloured (beige, light grey) clothing. If possible, wear long-sleeved, light-weight garments.
  • If available, pre-soak or spray outer layer clothing and gear with permethrin.
  • Get rid of water containers around dwellings and ensure that door and window screens work properly.
  • Apply sunscreen first followed by the repellent (preferably 20 minutes later).

Treatment of Japanese Encephalitis

There is no specific antiviral treatment for JE; therapy consists of supportive care and management of complications.

Japanese Encephalitis – Lifestyle Tips

Follow these lifestyle tips to alleviate symptoms of Japanese encephalitis :

  • Take proper food and avoid food that trigger Encephalitis like – Tea and coffee, Alcohol, Red meats, Breads, Pastas, Sugar etc
  • Music and Meditation – Meditation helps to relieve stress. Try to meditate for 15-30 min daily.
  • Take more rest.
  • Eat a healthy diet and keep your immune system healthy.
  • Drink plenty of water.
  • Protect yourself from mosquitoes

What are Recommended Exercises for Person with Japanese Encephalitis?

Exercise improves blood flow to the brain. This may include walking, massage etc. for at least 45 minutes per day.

Japanese Encephalitis & Pregnancy – Things to know

The safety of the Japanese encephalitis vaccine for use during pregnancy and breastfeeding has not been studied and the manufacturer recommends it is avoided. However, inactivated vaccines like this one are usually considered safe to use in women who are pregnant or breastfeeding.

Common Complications Related to Japanese Encephalitis

Generally infections caused by Japanese encephalitis virus are mild (fever and headache) or without apparent symptoms, but sometimes 1 in 200 infections can result in severe disease characterized by rapid onset of high grade fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and death.

Other FAQs about  Japanese Encephalitis

Q. How many injections do you need for Japanese encephalitis?

A. Primary immunisation should be completed at least one week prior to potential exposure to Japanese encephalitis virus. Once you have received both doses, you are protected against Japanese encephalitis for 12-24 months. After one year, you require a booster.

Q. Where is Japanese encephalitis found?

A. Japanese encephalitis is found throughout Asia and beyond. The area in which it’s found stretches from the Western Pacific islands in the east, such as Fiji, across to the borders of Pakistan in the west. It’s found as far north as parts of Russia and as far south as the north coast of Australia.

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