UMEM Educational Pearls

Category: International EM

Title: Japanese Encephalitis

Keywords: japanese encephalitis, international, virus, infectious disease (PubMed Search)

Posted: 2/20/2013 by Andrea Tenner, MD (Updated: 5/1/2024)
Click here to contact Andrea Tenner, MD

Japanese Encephalitis

General Information:

– caused by Japanese encephalitis virus (JEV), closely related to West Nile virus

– transmission is through infected mosquito

– most common cause of vaccine-preventable cause of encephalitis in Asia

– Incubation period is 5-15 days

– <1% develop clinical, disease, most asymptomatic

– Acute encephalitis most common presentation

– Sx: altered mental status, focal neuro deficits, movement disorder, seizure, fever, headache,

vomiting

– Classic presentation: Parkinsonian syndrome with mask-like facies, tremor, cogwheel rigidity, and

choreoathtoid movements

– case-fatality is 20-30%

Area of the world affected:

-- Primarily in Asia – China, Japan, Korea, India, Southeast Asia

Relevance to the US physician:

1. JE

-- Should be considered in patients concerned for neurological infection with recent travel to

endemic country

-- Lab: JEV-specific IgM in serum (after 7 days of sx onset) or CSF (after 4 days of sx onset)

-- Viral culture and other viral RNA amplifications tests are not sensitive

-- Treatment is supportive

-- In survivors, 30-50% have significant neurological/cognitive/psychological sequelae

2. Vaccine

-- One vaccine (Ixiaro) is available in the US

-- 2 doses, 28 days apart (96% develop immunity)

-- No information on duration of protection

-- Recommended for travelers ≥ 1 month in endemic areas during JEV season

Bottom Line:

Very rare but deadly disease with high mortality and post-infection sequelae. Think about it in travelers to Asia during summer/fall seasons who have not been immunized.

University of Maryland Section of Global Emergency Health

Author: Veronica Pei

References

http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/japanese-encephalitis.htm#2473