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Chapter 6 : Japanese Encephalitis Prevention and Control: Advances, Challenges, and New Initiatives
Category: Clinical Microbiology
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This chapter provides an overview of Japanese encephalitis (JE) epidemiology, prevention, and control and discusses recent advances, current challenges, and new initiatives in JE surveillance, diagnosis, and vaccines. Human vaccination is the most effective and sustainable measure to prevent JE. Interventions to control the mosquito vector or animal hosts may also lessen the number of human JEV infections; however, these methods have significant limitations. Urbanization, improved socioeconomic conditions, and changes in agricultural practices have contributed to significant reductions in the burden of JE in several Asian countries. There are three types of JE vaccines that are currently available. They are inactivated mouse brain-derived JE vaccine, live attenuated cell culture-derived SA 14-14-2 vaccine, and inactivated cell culture-derived P3 vaccine. Inactivated mouse brain-derived vaccines and a live attenuated cell culture-derived SA 14-14-2 vaccine are used in many countries. Inactivated cell culture-derived P3 vaccines are available only in China. Improved understanding of the epidemiology and an accurate measurement of the true JE disease burden in countries where it is endemic are needed to stimulate and guide the implementation of new vaccine strategies and policies. JE remains a significant but preventable public health problem. Substantial progress has been made in defining the true burden of illness and expanding the use of available vaccines. With sustained commitment and funding, safe, effective, and affordable JE vaccines can and should be integrated into the routine immunization programs in all areas where JE is endemic.
Key Concept Ranking
- Clinical and Public Health
Japanese encephalitis cases reported from selected countries in Asia, 1973 to 1990. Data for 1973 to 1990 include reported cases from China, South Korea, Japan, Vietnam, and Thailand; data for 1978 to 1990 also include cases reported from India and Nepal. Adapted from reference 63 .
Transmission cycle of JEV. JEV is transmitted in an enzootic cycle between Culex mosquitoes and amplifying vertebrate hosts, primarily pigs and wading birds. Humans are a dead-end host in the JEV transmission cycle, with brief and low levels of viremia. Humans play no role in the maintenance or amplification of JEV, and the virus is not transmitted directly from person to person.
Geographic range of JE. Reprinted from reference 35 .
Impact of JE vaccination in Japan, 1946 to 1999. Adapted from reference 62 .
Laboratory diagnostic assays to support JE surveillance
JE vaccines that are currently available or in clinical trials
Challenges and initiatives to improve JE surveillance, diagnosis, prevention, and management
Status of JE vaccination programs in Asian countries where it is endemic