Wednesday, March 1, 2017

Encephalitis in our Country The Burden of Japanese: How to Fight it?

Encephalitis - inflammation of the substance of the brain. Also called encephalitis lethargica a form of this condition, caused by a filterable virus and characterized by apathy and abnormal sleepiness; sleeping sickness.

Sanofi Pasteur held an awareness forum regarding the Japanese Encephalitis (JE). I haven't heard about JE, but I am aware that insect bites can and are indeed dangerous. JE is the leading cause of viral encephalitis in Asia. JE Japanese belongs to the same genus as dengue, yellow fever and West Nile viruses. It takes 5 to 15 days after the bite of an infected mosquito to develop symptoms. 24 countries in the WHO South-East Asia and Western Pacific regions have JEV transmission risk, which includes more than 3 billion people.

Signs and symptoms
Most JEV infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections results in severe clinical illness. Severe disease is characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and ultimately death. The case-fatality rate can be as high as 30% among those with disease symptoms.

Of those who survive, 20%–30% suffer permanent intellectual, behavioural or neurological problems such as paralysis, recurrent seizures or the inability to speak.

JE usually occurs in rural and agricultural areas, however, an epidemiologic study conducted by Dr. Anna Lena Lopez of the National Institute of Health (NIH) published in 2015, showed that the virus circulates in all regions of the Philippines, including urban areas like Metro Manila, constituting a significant public health burden.


Transmitted by the mosquito vector Culex tritaeniorhynchus, the virus can cause inflammation of the brain, leading to high fever, headache, fatigue, vomiting, confusion, and in severe cases, seizures, spastic paralysis, and coma.  It could also mimic a stroke, as was the case reported in Davao during the second half of 2016.2 There is no specific treatment for this disease.  JE is fatal in 20 to 30% of cases and among those who survive, 30 to 50% suffer from permanent disabilities.

Humans, once infected, do not develop sufficient viraemia to infect feeding mosquitoes. The virus exists in a transmission cycle between mosquitoes, pigs and/or water birds (enzootic cycle). The disease is predominantly found in rural and periurban settings, where humans live in closer proximity to these vertebrate hosts.

Imagine there are currently estimated 3 billion people at risk for JE, living in JE-prone areas, including 24 countries in the Southeast Asia and Western Pacific regions, Reports from the World Health Organization (WHO).

The study showed that although majority of cases occur in children younger than 15 years of age, adults remain at risk, with 15% of cases occurring in individuals older than 18 years.  In tropical areas, disease can occur year-round. Data from the Department of Health (DOH) Epidemiology Bureau surveillance system revealed that for 2016, among 875 acute meningitis-encephalitis suspected cases reported as of August 2016, 119 (14%) were laboratory-confirmed for JE.

As part of the government’s strategy to reduce mosquito-borne diseases, the 4S program was implemented several years back. 

Summary: Epidemiology of JE in the Philippines
  • JE is endemic in the Philippines
  • Surveillance data shows the JE virus circulates in ALL regions of the Philippines
  • 20-30% of those who develop JE die, majority of those who survive have physical disabilities
  • JE poses a public health burden in the Philippines

4S stands for:
Search and destroy mosquito breeding places
Self-protection measures
Seek early consultation for fever lasting more than 2 days
Say yes to fogging when there is an impending outbreak

According to the WHO, the most effective way of reducing disease burden is vaccination against the illness.  The WHO cites that there is clear evidence demonstrating the impact JE vaccination has on disease burden in a population. Hence, the WHO has recommended that JE vaccination be integrated into national immunization schedules in all areas where JE is recognized as a public health problem.  The WHO Global Advisory Committee on Vaccine Safety (GACVS) has reviewed data on the different types of JE vaccines (inactivated and live attenuated vaccines) and has found them to have acceptable safety profiles. Local scientific bodies, including the Philippine Pediatric Society (PPS) and Pediatric Infectious Disease Society of the Philippines (PIDSP), have recommended that JE vaccination be given as a single primary dose for those 9 months old and above.  For individuals less than 18 years of age, this should be followed by a booster dose 1 to 2 years after.  Other preventive strategies for disease control include bed nets, repellents, long-sleeved clothes, coils, vaporizers and mosquito control measures.  

About the Vaccine
The JE-chimeric vaccine, 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.  It is the only JE vaccine available locally and is approved for use for individuals 9 months old and above, with high immunogenicity rates.

There is no antiviral treatment for patients with JE. Treatment is supportive to relieve symptoms and stabilize the patient.

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