What You Should Know About Japanese Encephalitis

There are several alarming health-related news circulating on social media in recent weeks that have created paranoia and panic among the public, especially for parents like me. While I am more aware about dengue, I am part of the majority that is not fully informed on Japanese Encephalitis (JE). Anong sakit ba ito? Saan galing? Pano makaiwas diyan?

I only knew about isolated incidents from my immediate circle of friends who already had their kids vaccinated against JE. They paid between P2,500 to P4,000 per dose, including the professional fees (rate depends on the doctors and hospitals). The hype definitely raised a lot of concerns coz we all have young children. With the increasing reports in the news and online media, the Food and Drug Administration (FDA) and Sanofi Pasteur have come together to shed light on this disease.

Japanese encephalitis is a leading cause of viral encephalitis in Asia caused by the JE virus. Transmitted by the mosquito vector of the Culex species (mainly Culex tritaeniorhynchus), it exists in a transmission cycle between mosquitoes, pigs, and/or water birds.

During the Media Round Table Discussion on JE which I attended the other day, Dr. Salvacion Gatchalian, Philippine Pediatric Society VP, and PSMID President Mari Rose De los Reyes discussed the nature of Japanese Encephalitis, its effects on patients, and preventive measures to consider.

So, what do we need to know about Japanese Encephalitis?

Key Facts About Japanese Encephalitis and Disease Prevention

Japanese Encephalitis is endemic in the Philippines. Virus circulates in all regions, including urban areas like Metro Manila, with transmission all year round. No specific treatment for this disease.

  • 133 cases of Japanese Encephalitis in the Philippines (from DOH, as of August 2017)
    • 9 of which resulted in death
    • 53 cases were recorded in Central Luzon
  • Increased demand for the JE vaccine
    • Sanofi Pasteur is the sole manufacturer of the vaccine; Zuellig Pharmaceutical is the authorized local distributor
    • FDA advisory warned the public against purchasing JE vaccines online as these sellers are not authorized; safety of online products has not been verified

  • 3 billion people in transmission risk areas in 24 Southeast Asian and Western Pacific countries
  • No season, occurs all year round in tropical countries
  • Predominantly found in rural and agricultural areas, low-lying flood areas, pools, beaches, flooded grass
  • Affects mostly children below 15 years old

  • High fever
  • Headache
  • Fatigue
  • Vomiting
  • Confusion
  • In severe cases, seizures, spastic paralysis, and coma

  1. Vector Control Measures - Environmental, chemical, and personal protection measures
  2. Surveillance and clinical management
  • Avoid mosquito bites
    • Use insect repellent, bed nets, pants/long-sleeved clothes, coils, vaporizers, mosquito control measures
    • Reduce exposure during peak biting hours (dusk to dawn)
  • Vaccination - recommended by WHO
    • Integrated into the national immunization programs in all areas where JE is recognized as a public health priority
    • Even with low number of cases, vaccination should be considered where there is a suitable environment for JEV transmission
    • High vaccination coverage should be achieved and sustained in populations at risk
    • Vaccination for 9 months old and above - as recommended by local medical societies, including the Philippine Pediatric Society (PPS) and Pediatric Infectious Disease Society of the Philippines (PIDSP)
      • 9 months to 17 y.o. = 1 primary dose + 1 booster dose after 12-24months
      • 18y.o and above = 1 primary dose
    • JE in humans can be greatly reduced despite ongoing transmission in animals

Like with any medical concerns, please consult your doctors if you have further questions about JE and the vaccine.

View the public advisories from WHO, FDA and Sanofi Pasteur here: 

About the Vaccine:
JE-chimeric vaccine (JE-CV), a live attenuated recombinant vaccine, was first licensed in the Philippines in 2013.
The vaccine is produced by Vero cell culture, a cell culture technology recommended by WHO. Different clinical phase studies have demonstrated its high immunogenicity and acceptable safety profile in both adult and pediatric populations. It is contraindicated for those with a history of allergy to the vaccine or any of its components, immunodeficiency, and to pregnant or lactating women. The public is advised to visit their doctors to know more about JE and how to prevent the disease.

WHO Weekly epidemiological record. Japanese Encephalitis Vaccines: WHO position paper – February 2015. 27 Feb 2015; 9 (90): 69-88.
World Health Organization 2017. Western Pacific Region Health Topics: Japanese Encephalitis. Retrieved from: http://www.wpro.who.int/topics/japanese_encephalitis/en/
Lopez A et al. Epidemiology of Japanese Encephalitis in the Philippines: A Systematic Review.  PLOS Neglected Tropical Diseases, Mar 2015.  
World Health Organization. Media Centre: Japanese Encephalitis Fact Sheet. Dec 2015. Retrieved from: http://www.who.int/mediacentre/factsheets/fs386/en/
Philippine Foundation for Vaccination. Childhood Immunization Schedule 2016. Retrieved from http://www.philvaccine.org/vaccination-schedules/childhood-immunization-schedule 
Xing Li et al. Immunogenicity and Safety of Currently Available Japanese  Encephalitis Vaccines: A systematic review. Hum Vaccin Immunother. 2014 Dec; 10 (12): 3579-3593.
Japanese encephalitis vaccine (live attenuated) (Imojev®) Package insert. Date revised 08 Dec 2013.

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