National Vector Borne Disease Control Programme
- Japanese Encephalitis (JE)
Background / Periodical Development
Japanese Encephalitis is a disease of Public Health importance
because of it's epidemic potential and high Case Fatality Rate.
It is mosquito borne zoonotic disease. It is primarily the disease
of rural agricultural areas where mosquitoes proliferate in close
association with pigs & other animal reservoirs. It's epidemic
have also been reported in peri-urban & urban areas where similar
conditions may exists.
JE in world :
The virus infection is known to occur in Eastern Siberia, China,
Japan, all of East Asia, Guam, Nepal & India. JE was described
clinically in 1871 in Japan. It was formerly called Japanese B Encephalitis
to distinguish it from Economo or type A encephalitis. The JE virus
was isolated in 1935 from brain of fatal encephalitis cases and
mosquito transmission was demonstrated in 1938. Since late 1960s,
JE has virtually disappeared in Japan (,20 cases annually) and is
declining in China (<10,000 cases annually). However, it remains
a major problem in northern Thailand ( attack rates of 10 to 20
per 100,000 annually). In temperate climates, epidemics occur mostly
in post monsoon months.
JE now occurs mainly in India, Nepal, China, Thialand & Vietnam
and sporadicaaly in Indonaesia, Singapore & Malaysia. In endemic
areas, children between ages 2 & 15 primarily affected. In non
endemic areas all the age groups are affected, children & older
adults being the predominant victims.
JE in India :
In india, the disease was first reported in the mid 1950's from
vellore in Tamil Nadu State, where cases of an encephalitis like
illness were seen and serologically proven to be due to je or closely
related to it. over the next decade, 52 cases of encephalitis presenting
at the Christian Medical College, Vellore were identified to be
JE. Around the same time, extensive serological surveys in South
India revealed widespread flavivrus activity.
The first major epidemic of JE from India was reported from the
Bankura and Burdwan districts of West Bengal in 1973. Since then,
repeated annual outbreaks have occurred especially in the post monsoon,
high mosquito season in West Bengal, Bihar, Aasam and the North
East, Uttat Pradesh and the 3 southern states of Tamil Nadu, Karnataka
& Andhra Pradesh. Sporadic cases are reported in the i nter
epidemic periods also.
The first JE epidemic in the West Coast was reported from Goa in
1993. An outbreak of JE was reported from HAryana in 1990 and the
disease was also seen in Orissa. Kerala Experienced the first epidemic
in 1996. Thus it is clear that the disease is highly prevalent in
southern and eastern parts of the country and it is also making
inroads into newer areas. So far, epidemics are occurring in alternate
JE in Maharashtra :
Till 2001, there was no problem of JE in Maharashtra State. But
during 2002 & 2003 J. E. infection was introduced in eastern
districts such as Bhandara, Gondiya, & Nagpur of Maharashtra
State, where there was a focal outbreaks leading to 16 & 115
deaths respectively. During 2004 there were only 3 focal outbreaks
of JE in districts Gadchiroli, Parbhani & Wardha & during
2005, there were 6 focal outbreaks of JE in Amravati, Yeotmal & Nagpur
districts, leading no deaths occurred due to JE.
During June to August 2003, an outbreaks not confirmed as JE,
reported from various parts of Nagpur division in Maharashtra.
Similar outbreaks were reported from other states like A.P., Gujarath,
Bihar also. The disease was labled as nagpur fever, Reye's syndrome,
unusual measles etc. without proper verification of the etiological
Total 393 Encephalitis cases with 115 deaths were reported during
June to August 2003, from 15 districts of Maharashtra. Clinical
samples of 202 cases were sent to NIV, Pune. All cases were in
pediatric age group below 15 years age. There was no clustering
and Usually a single case in villages was recorded.