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Ten facts about Japanese encephalitis

Japanese encephalitis virus (Flavivirus) | Vaccines at Sanofi

1. There is no treatment for Japanese encephalitis

There is no specific treatment for Japanese encephalitis. Treatment is mainly supportive, and can include hospitalization, management of symptoms, and prevention of complications. There is no antiviral medication that works for Japanese encephalitis. The recovery process can be lengthy and some people may experience long-term neurological problems such as seizures, weakness, and difficulty with coordination. Some people may also experience permanent brain damage or death.

2. Japanese encephalitis is endemic to most of Asia

Japanese encephalitis is endemic in many parts of Asia and the Western Pacific, including Japan, China, Southeast Asia, and the Indian subcontinent. It is most common in rural areas where there is more contact with mosquitoes and where rice paddies and pig farms are present. The disease is also found in parts of Australia, and in some Pacific islands.

In particular, the countries with the highest burden of Japanese encephalitis are China, India, Indonesia, Bangladesh and Vietnam. However, the disease is also found in other countries of the region such as Nepal, Thailand, Philippines, Myanmar, Cambodia and Laos. It's important to note that the risk of contracting Japanese encephalitis can vary depending on the specific area within a country and the time of year.

3. Japan encephalitis is actually not that bad in Japan

Japan is not considered to be an area with a high burden of Japanese encephalitis. In the past, Japan had a high incidence of Japanese encephalitis, but due to the implementation of control measures such as mosquito control and vaccination, the incidence of the disease has greatly decreased. The cases of Japanese encephalitis in Japan are now considered to be rare and mostly restricted to the rural areas of the main island of Honshu.

4. There is a very effective vaccine for Japanese encephalitis

Yes, there is a vaccine for Japanese encephalitis. The vaccine is called Ixiaro, and it is produced by Valneva. The Japanese encephalitis vaccine is highly effective in preventing Japanese encephalitis and is recommended for travelers going to areas where the disease is prevalent, as well as for people who live in or frequently visit those areas.

For travelers, the recommended schedule is two doses, given 28 days apart, before departure. A booster dose is recommended for those who will continue to be at risk for more than a year after the primary series. There is also an accelerated schedule where you can get the two shots 7 days apart.

It's important to note that the vaccine may not be 100% effective and that other preventive measures, such as using mosquito repellent and wearing long sleeves and pants, should also be taken to reduce the risk of contracting the disease. It's also important to talk with a healthcare provider before getting the vaccine, as some people may not be able to receive it, such as pregnant women or people with certain health conditions.

5. Most people exposed to the virus don't develop full-blown Japanese encephalitis

Most Japanese encephalitis infections are asymptomatic. Approximately 1% will develop flu-like symptoms, and less than 1% of those with flu-like symptoms will develop full-blown Japanese encephalitis.

6. There is a 30% mortality rate for people who do develop Japanese encephalitis

People who get full-blown Japanese encephalitis (approximately 2 people out of 100,000 who get the virus) have a 30% chance of dying. Full-blown Japanese encephalitis means brain swelling.

7. Up to 50% of Japanese encephalitis survivors have life-long symptoms and disabilities

Up to 50% of survivors continue to have neurologic, cognitive, and psychiatric symptoms.

8. Japanese encephalitis causes brain swelling

Encephalitis means inflammation of the brain. Encephalitis can be caused by a variety of things, including viruses, bacteria, and other infectious agents, as well as autoimmune disorders, and reactions to certain drugs or toxins. When caused by a viral infection, it is called viral encephalitis. Some viruses besides Japanese encephalitis that can cause encephalitis are: Herpes simplex virus, West Nile virus, measles, mumps and rabies.

9. Japanese encephalitis is spread by mosquitoes

Japanese encephalitis (JE) is spread through the bite of an infected mosquito, specifically Culex mosquitoes. The virus is primarily transmitted by the mosquito species Culex tritaeniorhynchus and Culex vishnui.

The disease is more common during the rainy season when mosquitoes are more prevalent. People who travel to areas where JE is prevalent, particularly rural areas, are at higher risk of contracting the disease. It's important to take preventive measures such as using mosquito repellent and wearing long sleeves and pants to reduce the risk of being bitten by mosquitoes. Also, there is a very effective Japanese encephalitis vaccine.

10. Pigs and birds are necessary hosts to continue the life and reproductive cycle of the virus

The Japanese encephalitis virus is maintained in a cycle between mosquitoes and animals, particularly pigs and wading birds, which act as amplifying hosts. Humans are considered dead-end hosts, meaning that they don't carry enough of the virus to spread it to other humans via mosquitoes.

The mosquitoes acquire the virus by feeding on infected animals and then transmit the virus to humans by biting them. The transmission of the virus is most common in rural areas where there is more contact with mosquitoes, and rice paddies and pig farms are known to be high-risk areas.

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