Three billion people are at risk for Japanese encephalitis (JE) according to THE World Health Organization (WHO). Most of these people live in JE-prone areas, usually rural and agricultural areas, in 24 countries in the Southeast Asia and Western Pacific region.
With an average fatality rate of three out of every 10 patients who exhibit severe symptoms, JE affects about one out of every 250 people who contract the illness.
The first case of the JE viral disease was documented in 1871 in Japan, thus, its name, Japanese encephalitis.
JE is transmitted by the Culex tritaeniorhynchus, a mosquito endemic to tropical and sub-tropical countries. The disease is present in all regions of the Philippines, as well as throughout most of Asia.
Most infections are mild (fever and headache) or without apparent symptoms. 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 percent among those with disease symptoms. Of those who survive, 20 to 30 percent suffer permanent intellectual, behavioral or neurological problems such as paralysis, recurrent seizures or the inability to speak.
Children below the age of 15 are most susceptible to the disease, with children younger than four years being nine times more likely to be infected than older children. About 15 percent of Japanese encephalitis cases are adult victims. In the Philippines, JE is often underreported and unrecognized for various reasons such as lack of confirmatory lab facilities in many areas and lack of disease surveillance.
There is no antiviral treatment for patients with JE. Treatment is supportive to relieve symptoms and stabilize the patient. Safe and effective JE vaccines are available to prevent the disease. A WHO-recommended vaccine has been licensed for use in the Philippines since 2013.
Countries that have implemented JE vaccination have managed to reduce the burden of disease. China, Korea, Japan, Taiwan, and Thailand have had outbreaks in the past, but they have mainly controlled the disease by vaccination. Vietnam, Cambodia, Myanmar, India, Nepal, and Malaysia still experiences epidemics occasionally. A lot of countries now, including our neighboring countries, have implemented JE vaccination either as targeting entire populations or select areas, where burden of disease is highest.
The media forum led by Dr. Cynthia Aguirre, Pediatric Infectious Disease Consultant (from Medical City and National Children’s Hospital) and Dr. Lulu Bravo, founding president of the Philippine Foundation for Vaccination, highlighted the importance of immunization as the most effective way of reducing the risk of developing encephalitis.
The government immunization program so far includes vaccines for Diphtheria-Pertussis-Tetanus, measles, mumps, rubella, and oral polio vaccine.
The vaccine experts advise people in areas known to have mosquitoes that carry encephalitis-causing viruses to take necessary measure to reduce the risk of being bitten. This may include wearing appropriate clothing, avoiding mosquito-infested areas, avoiding going outside at specific times during the day when there are lots of mosquitoes about, keeping your home mosquito-free, using mosquito repellant, and making sure there is no stagnant water about your house.
For vaccination inquiries and schedules, visit your pediatrician or infectious disease doctor.