Japanese encephalitis refers to a viral disease, which infects both human and animals. The disease is caused by a flavivirus, which affects the membranes surrounding the brain. Mosquitos that breed on rice fields transmit the virus. Most of the infections are mild and are characterized by fever and slight headache. Sometimes, the mild infections lack noticeable symptoms. However, one out of 200 people infected with the virus become severely affected. Such individuals exhibit symptoms like fast start of high fever, coma, stupor, tremors, disorientation, headache, convulsive paralysis, and death. Sixty percent of the symptomatic cases end up dying, whereas 30% who survive suffer long-term nervous damage. In regions where the virus is prevalent, the disease catches young children, since the adults and the older children are immune because they have previously been infected. The incubation period of the disease takes between five to fifteen days (CDC, 2010).
Encephalitis disease is transmitted when a mosquito feeds on domestic pigs as well as wild birds infected with the Japanese flavivirus. In turn, the infected mosquitoes transmit the virus to humans and animals while feeding. The mosquitoes bite their hosts and infect them with the virus. The flavivirus is augmented in the animals’ blood system and results into the Japanese encephalitis disease. The specific mosquitoes carrying the Japanese virus belong to two groups namely the Culex tritaeniorhynchus and Culex vishnui. These mosquitoes breed specifically in flooded rice meadows (Bauman, 2012).
Individuals at risk of the infection include those living in rural endemic areas, expatriates and active duty military positioned in prevalent regions. Japanese encephalitis does not often occur in urban areas (CDC, 2012). The outbreaks of the disease are often limited and occur in a small area. They last for a few months and deaths occur once the amplifying pigs acting as the hosts are infected. The natural hosts of the Japanese virus are birds. Epidemics happen when the virus is exposed to the domestic environment via mosquitoes that later infect humans. Nations that have experienced main epidemics long ago and have been able to control the disease largely through vaccination are Thailand, Taiwan, Korea, China and Japan. Nations like Nepal as well as Cambodia among others still have sporadic epidemics.
In addition, Japanese flavivirus is the main origin of encephalitis in Asia with about 30,000 to 50,000 clinical cases accounted yearly. The disease in Muslim nations is negligible because of the significant role of pigs in transmitting the virus. The distribution of the virus is considerably related with production of irrigated rice together with pig rearing. Notably, the disease is patchy and significant outbreaks have happened in numerous areas, in the past 15 years e.g. in South India and Sri Lanka (WHO, 2012).
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There is an effective vaccine for the disease although it is expensive and requires one main vaccination followed by two boosters. This intervention is sufficient for travelers, although it has restricted public health significance in the regions where health services lack sufficient resources. The Chinese use a live-attenuated vaccine, which is cheap although unavailable elsewhere. Control using chemical vectors is not a remedy because the breeding sites are widespread. Particular water management measures may be employed in some rice production systems encountering water shortages. This is because the water shortage may decrease vector populations (Bauman, 2010).
Additionally, personal protection may be effective under particular conditions. This may be achieved by using mosquito nets and using repellents. Getting rid of the pig population is frequently a precaution taken in the war against outbreaks. Rice-growing farmers should be discouraged to rear pigs in receptive areas.
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