Encephalitis, Japanese

Japanese encephalitis (JE) is a mosquito-borne arbovirus infection, with seasonal distribution. It is endemic in parts of China, India, the Republic of Korea, Japan, the Russian Federation, islands in the Torres Strait of Australia, Nepal, Thailand, Viet Nam, Cambodia, the Lao People's Democratic Republic, the Philippines, Papua New Guinea, Taiwan, Indonesia, Malaysia, and Sri Lanka. Japanese encephalitis virus belongs to the Flaviviridae family, genus Flavivirus. Large outbreaks of JE in India and Nepal have highlighted the continuing expansion of the geographic range of JE in recent years.

Japanese encephalitis is the leading cause of viral encephalitis in Asia. There is no JE-specific therapy other than supportive care. Most infections result in mild symptoms or no symptoms at all. On average, 1 in 300 infections results in symptomatic illness, which is characterized by a flu-like illness with sudden onset of fever, chills, headache, tiredness, nausea, and vomiting. The illness can progress to encephalitis (infection of the brain) and can be fatal in 30% of cases.

China organizes national Japanese Encephalitis workshop

28–29 September 2011, Chengdu, China

The China Centers for Disease Control (China CDC) organized a "National Workshop on Japanese Encephalitis Surveillance and Laboratory Testing" from 28 to 29 September, 2011 in Chengdu, China. More than 65 participants from China CDC, selected provincial CDCs, vaccine manufacturers and the World Health Organization attended. Officials from China CDC presented summaries of national Japanese encephalitis (JE) surveillance data and recent JE related research activities followed by presentations by nine provincial CDCs on JE incidence, disease burden and vaccination data. Most provincial laboratories conduct vector (mosquito) surveillance, pig serosurveillance and healthy children serosurvey as well as JE/Acute Encephalitis Syndrome surveillance. The first JE vaccine came into use in China in the 1970s, and the number of reported JE cases has gradually declined since then, but China still accounts for an estimated half of global JE cases. JE vaccine was added to the national EPI schedule in 2008 to accelerate JE control. Experience presented from the provinces in this meeting suggests that routine JE vaccine use along with catch-up campaigns has had an impact. The China CDC JE laboratory is a WHO Regional Reference Laboratory and provides training and quality assurance for a network of provincial and lower-level laboratories, which conduct primary testing for JE. In 2011, China's Ministry of Health will designate 10 subnational JE laboratories in China, which will also collaborate with the Western Pacific Regional Office.

Fact sheets

No fact sheets available at this time.

News and press releases

21 April 1999
Viral Encephalitis Outbreak in Malaysia Declining
[full text]

09 April 1999
Viral Encephalitis in Malaysia and Singapore
[full text]

25 March 1999
Epidemic Encephalitis in Malaysia
[full text]

Relevant publications and documents

4th Biregional meeting on the control of Japanese Encephalitis

Technical Advisory Group (TAG) on Immunization and Vaccine Preventable Diseases in the Western Pacific Region (18th Meeting - 30 June-2 July 2009) - Meeting Report
The 18th meeting of the Technical Advisory Group (TAG) on Immunization and Vaccine-Preventable Diseases (VPDs) in the Western Pacific Region (WPR) was held from 30 June to 2 July 2009 in Manila, Philippines. A meeting of the Regional Interagency Coordinating Committee was convened concurrently with the TAG Meeting, as in previous years.