Rahul Kapoor

Japanese Encephalitis Affects CNS and can cause severe complications and even death. Cause : Japanese Encephalitis virus (arbovirus) Vector : Rice field breeding mosquito primarily Culex tritaeniorhynchus No human to human transmission. It is most seen in Southeast Asia and the Far East. 30,000-50,000 cases are reported annually.

Basic Transmission Cycle Mosquitos become infected by feeding on pigs and wild birds infected with JEV. The JE virus is amplified in the blood of pigs and wild birds. The infected mosquitos transfer the amplified virus to humans and animals.

Pathophysiology The virus initially propagates at the site of the bite and the regional lymph nodes. Viremia develops causing inflammatory changes in heart, liver, lungs and reticuloendothelial system. Neurologic invasion can develop, possibly by growth of the virus across vascular endothelial cells. Large areas of brain can be involved including basal ganglia, thalamus, brains stem, hippocampus and cerebral cortex

Signs and Symptoms Symptoms usually appear after 6-8 days after the mosquito bite. MILD INFECTION : No apparent symptoms except fever + headache SEVERE INFECTION: Quick onset of high fever, headache, neck stiffness, disorientation, tremors, coma, occasional convulsions and spastic paralysis. If it progresses to encephalitis, it can be fatal in 30% of the cases. Among the survivors, 30% have serious brain damage, including paralysis. Diagnosis is based on tests of blood or CSF.

Occurrence around the Globe JE is the leading cause of viral encephalitis in Asia. 30,000-50,000 cases each year. Countries which have had major epidemics in the past, but which have controlled the disease primarily by vaccination, include China, Korea, Japan, Taiwan and Thailand. Countries that still have periodic epidemics include Vietnam, Cambodia, Myanmar, India, Nepal, and Malaysia. Japanese Encephalitis is seen in southeast Asia and far east

Treatment and Prevention No anti viral drugs have been discovered against JE so far. Intensive Supportive Therapy (nutrition, control of infection, intensive care) is indicated. Vaccines against JEV provide immunity against the virus. Can also be prevented by preventing mosquito bite (use of repellents etc) Drainage of stagnant water.

Acknowledgement

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