**4. Epidemiological cycle of Japanese encephalitis**

Japanese encephalitis (JE) is caused by a Flavivirus that, in a human case, causes severe en‐ cephalitis leading to death or permanent disablement. It is a zoonotic disease, transferred from animals (commonly domestic pigs but wild boars and migratory birds may also be im‐ portant amplifier hosts and reservoirs) by a mosquito vector to humans. Important social factors may also play an important role in JE transmissions with the poorest sectors of the population most often affected (e.g. people sleep outside during hot humid months where the vector density is at peak, and often sleep close to pigs). JE has been occurring in the South-East Asia and Western Pacific Regions for a long time. In Southeast Asia it is thought to cause up to 50000 clinical cases and 10000 deaths per year (WHO, 1979). Japan, China and Republic of Korea have reduced the incidence of this disease now (WHO/SEARO 1979). These countries had very well developed long term plan to control the epidemicity of JE by regular vaccination in children and pigs they had also improved pig husbandry system and also vector control by draining the water from the rice field on a regular interval period.

JE cases are observed mostly in Terai region of Nepal (Joshi, 1983). 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 (Joshi, 1983, 1986, 1987, Joshi et al., 1994). In Nepal, JE occurred first time during the year 1978 in Rupandehi district then in Sunsari, Morang and has since be‐ come endemic in all 24 districts of Terai and Inner Terai (Joshi, 1983). JE is a seasonal disease in Nepal, it occurs as an epidemic form only in the rainy (monsoon) season (July to October).

In Nepal, about 5000 people died due to JE from the year 1978 to 2006. Every year 3000 to 4000 people at risk and about 200-300 people die from complications associated with JE. About 12.5 million people in Nepal live in JE risk areas. Children who are less than 15 years of age are more likely to develop disease during a JE outbreak. Approximately 50% of JE survivors are left with chronic neurological syndrome and organ damage.

The highest morbidity 7.94% was seen in Kailali district. JE cases diagnosed, reported and recorded by Child Health Division of DHS, during the year 2011 in Nepal are shown in table no. 2.


Source: Child Health Division, IPD Section, WHO, 2011

person's blood stream. The worms grow and live in an infected person's lymph vessels for about 7 years and divide in the lymphatic system. This causes inflammation and eventually

The government is trying again to eradicate this disease by distributing the drug called Di‐ ethlcarbamazine- a three tablets-at-a-time treatment, and a single tablet treatment of Alben‐ dazole. However the medical fraternity is in doubt about its continuation. Saving the most important of all disease for the last, malaria, which is transmitted by the female Anopheles mosquito, causes febrile disease. One of the agents called Plasmodium Falciparum causes very severe malaria, which can lead to death. Again there is no vaccine against this agent. But effective drug prophylaxis has been in use to prevent the disease. Nonetheless mosquito

Japanese encephalitis (JE) is caused by a Flavivirus that, in a human case, causes severe en‐ cephalitis leading to death or permanent disablement. It is a zoonotic disease, transferred from animals (commonly domestic pigs but wild boars and migratory birds may also be im‐ portant amplifier hosts and reservoirs) by a mosquito vector to humans. Important social factors may also play an important role in JE transmissions with the poorest sectors of the population most often affected (e.g. people sleep outside during hot humid months where the vector density is at peak, and often sleep close to pigs). JE has been occurring in the South-East Asia and Western Pacific Regions for a long time. In Southeast Asia it is thought to cause up to 50000 clinical cases and 10000 deaths per year (WHO, 1979). Japan, China and Republic of Korea have reduced the incidence of this disease now (WHO/SEARO 1979). These countries had very well developed long term plan to control the epidemicity of JE by regular vaccination in children and pigs they had also improved pig husbandry system and also vector control by draining the water from the rice field on a regular interval period.

JE cases are observed mostly in Terai region of Nepal (Joshi, 1983). 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 (Joshi, 1983, 1986, 1987, Joshi et al., 1994). In Nepal, JE occurred first time during the year 1978 in Rupandehi district then in Sunsari, Morang and has since be‐ come endemic in all 24 districts of Terai and Inner Terai (Joshi, 1983). JE is a seasonal disease in Nepal, it occurs as an epidemic form only in the rainy (monsoon) season (July to October).

In Nepal, about 5000 people died due to JE from the year 1978 to 2006. Every year 3000 to 4000 people at risk and about 200-300 people die from complications associated with JE. About 12.5 million people in Nepal live in JE risk areas. Children who are less than 15 years of age are more likely to develop disease during a JE outbreak. Approximately 50% of JE

The highest morbidity 7.94% was seen in Kailali district. JE cases diagnosed, reported and recorded by Child Health Division of DHS, during the year 2011 in Nepal are

survivors are left with chronic neurological syndrome and organ damage.

shown in table no. 2.

blocks the lymphatic system and causes a lot of disfiguration.

58 Encephalitis

prevention and control is the key against all these disease.

**4. Epidemiological cycle of Japanese encephalitis**

**Table 2.** JE cases diagnosed, reported and recorded by Child Health Division of DHS, during the year 2011 in Nepal

Larva of *Culex sps.*

**Figure 1.** Epidemiological cycle of JE transmission. Source: Joshi, et al., 2012.

**Bhaktapur District**

**5. District (province) wise JE cases recorded during the year 2011:**

**Bhaktapur hospital sees surge in Japanese encephalitis (viral fever) patients**

has also increased according to the District Public Health Office, Bhaktapur.

The number of viral fever patients has increased in most of the hospitals in Bhaktapur dis‐ trict coinciding with the change in weather. Many people suffering from viral fever have been coming to the hospitals and health centre in the district. Along with the upsurge in the number of viral fever patients, the number of people suffering from typhoid and jaundice

Superintendent at the Bhakatapur Hospital, Dr. Indra Prajapati said the diseases might take epidemic proportion if timely measures are not taken. Health Official in the district say the spread of viral fever is also because patients in the rural areas of the district have the habit of only taking paracetamol tablets that they buy at local drug stores instead of visiting the doc‐ tors for a thorough check-up. As many as 100 people suffering from fever come to the Bhak‐ tapur Hospital daily for treatment, and many of them only after advanced stage of the

Adult *Culex traetaniorhynchus*

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

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**Figure 1.** Epidemiological cycle of JE transmission. Source: Joshi, et al., 2012.
