**1. Introduction**

Nepal is one of the richest countries in the world in terms of bio-diversity due to its unique geographical position and altitudinal variation. The elevation of the country ranges from 60 m above sea level to the highest point on earth, Mr. Everest at 8,848 m, all within a distance of 150 km resulting into climatic conditions from subtropical to artic mentioned by Nepal Tourism Board, 2006. JE cases are observed mostly in Terai area (The lowland plains of the Terai lie at an altitude of between 67 and 300 m (220 and 980 ft tropical climate) (Joshi, 1983). In Southeast Asia it is thought to cause up to 50000 clinical cases and 10000 deaths per year (WHO/SEARO, 1979). The earlier reports have shown that the case fatality rate (CFR) is high in Nepal, and nationwide it has ranged from 15% to 46% for the years 1978 to 1994. There are 75 districts, 14 zones and five development regions in Nepal. Out of 75 districts 36 dis‐ tricts are affected by Japanese encephalitis.

Japanese encephalitis (JE) has been occurring in the South-East Asia and Western Pacific Regions for a long time. In Nepal, it has occurred first time in Rupandehi district then in Sunsari, Morang and latter in all 23 districts of Terai and inner Terai (Joshi, 1983). Inci‐ dence of this disease has been recorded first time in different years in the following countries. Japan, China and Republic of Korea have reduced the incidence of this disease now (WHO/SEARO, 1979).

The entomological survey conducted in May/June, 1981 at the endemic areas of western re‐ gion of Nepal, have recorded the prevalence of the following species such as (a) *Culex tritae‐ niorhynchus*, (b) *Cules vishuni*, (c) *Culex gelidus*, (d) *Culex fusecephalus*, (e) *Culex epidesmas* (f) *Culex bitaeniorhynchus* (g) *Mansonia annulefera* (h) *Mansonia indiana* (i) *Mansonia uniformis*, (j) few species of genus *Aedes*, genus *Armigeris* and genus *Anopheles* (Pradhan, 1981).

© 2013 Joshi and Marg; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

These mosquitoes can breed in sub-urban and peri-urban area provided the ecological con‐ ditions similar to rural area are present (Pradhan, 1981, Khatri et al., 1981, 1983). These mos‐ quitoes can breed same environment wherever it is favourable.

**3. Japanese encephalitis distribution in Nepal**

**Scheme 1.** Map 1.

This JE virus is transmitted through a series of bites -when the mosquito bites a pig, for in‐ stance, it transmits the virus to the pig which acts as a host to the virus. The virus is further

Review on Japanese Encephalitis Outbreak Cases in Nepal During the Year 2011

http://dx.doi.org/10.5772/52422

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The virus attacks the central nervous system of human, causing encephalitis-an infection of the brain. The patients starts vomiting, suffers severe headache and fever gradually becomes unconscious and nears death due to brain swelling. Even if the patients survive they remain with a lot of deflect- both physical and intellectual. Such a deadly disease, so wide spread in Nepal and without a cure. Preventing mosquito bite is thus so very important. But unlike for dengue virus, there is a vaccine for Japanese B virus which the government is trying to make

The mosquitoes that transmit this disease breed in and around dirty, stagnant water and in areas where the pigs are farmed. We all know that there are many places in and around Kathmandu that fits into this description, so I would urge you to hurry and get vaccinated. Another disease Filarisis- is also transmitted through the disease vector that is the female *Culex* mosquito. Filariasis is spread from infected persons to uninfected persons by mosqui‐ toes that release large numbers of very small worm larvae, which circulate in an affected

available in mass. Japanese encephalitis virus also called Japanese B virus.

transmitted to humans when bitten by mosquitoes who have already bitten the pig.


**Table 1.** Historical reviews of JE outbreak worldwide.
