Vazhavandal, G (2009) Study on Efficacy and Safety of Sa -14-14-2 Vaccine against Japanese Encephalitis Virus at Viruthunagar District. Masters thesis, Madurai Medical College, Madurai.
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Abstract
INTRODUCTION: Background Japanese encephalitis is the leading viral cause of Acute Encephalitis Syndrome (AES) in Asia. The disease primarily affects children under the age of fifteen. 70% of Those who develop illness either die or survive with a long term neurological disability. Since the first Case of JE was documented in the late 19th century; the disease has spread Beyond its early domain- traveling as far as Australia by 2000.Over the past 60 years it is Estimated that JE has infected~ 10 million children globally, killing 3 million and Causing long-term disability in 4 million. Current Scenario in India JE virus transmission has been widespread in India. The first evidence of presence Of JE virus dates back to 1952 in Nagpur subdivision of Maharashtra. JE was clinically Diagnosed for the first time in 1955 at Vellore, North Arcot district of Tamil Nadu. In Subsequent years, outbreaks have occurred in various states and Union Territories ( uts) in the country. The first major JE epidemic was reported from Burdwan and Bankura districts of West Bengal in 1973 followed by another outbreak in 1976. Outbreaks have been reported from States like Uttar Pradesh, West Bengal, Assam, Andhra Pradesh, Karnataka, Bihar, Tamil Nadu, Haryana and other states through the Years. The Directorate of National Vector Borne Disease control Programme (NVBDCP) Formerly known as the National Anti Malaria Programme (NAMP) has been monitoring JE incidence in the country since 1978. Though cases of JE have been reported from 26 States and UT’s occasionally in some years since 1978, repeated outbreaks have been Reported only from 12 States. The table below highlights the case load in some of the states during last 5 years (2001- 2005). However, the disease reporting has been passive without adequate Diagnostic support. These are reported cases through passive surveillance without Adequate diagnostics support. The Case Fatality Rate (CFR) due to JE in India has been around 24 % with wide Variations in states. Annual reported cases due to JE ranges between 1037 and 6550 While deaths due to JE range between292 and 1645. THE EPIDEMIOLOGY OF JAPANESE ENCEPHALITIS The JE Virus JE virus (JEV) is a member of the genus Flaviviridae, together with Yellow Fever Virus and Dengue virus. With the help of genome sequencing studies, it has been Possible to determine the various genotypes of JEV in circulation in different geographic Areas. The two common Indian Genotypes [GP78 and Vellore P20778] show genetic Similarity to Chinese SA14 and Beijing Genotypes. Communicability and transmission JE is a Zoonotic viral disease. JE virus has a complex life cycle. In nature, JE Virus is maintained in animals and birds, particularly pigs and Ardied birds (e.g., Cattle Egrets, pond herons etc.).The virus does not cause any disease among its natural hosts And the transmission continues unnoticed through mosquitoes. It is carried by female Mosquitoes from infected pigs or water birds like pond herons and ducks to susceptible Children. The main vector, Culex Mosquitoes (Culex tritaeniorhynchus, C.vishnui, C.pseudovishnui and others totally 8 species) live in rural rice growing and pig-farming Regions. The mosquito breeds in flooded rice fields, marshes, and standing water around Planted fields. This is the reason why JE is mostly a rural disease. JE is a seasonal disease. Epidemics coincide with the monsoon and post monsoon Period (August to December) in Tamilnadu & agricultural pratices, during this period, Due to high density of the mosquito vector because of stagnant water and presence of Reservoir host (pigs). Pigs are the most important reservoirs. Though they do not manifest the disease, They develop very high titers of virus in circulating blood and infect mosquitoes. Thus Pigs are the amplifying hosts. Susceptible children are infected by infected mosquito Bites. After mosquito bite, disease appears in 5-16 days. The virus then invades the Central nervous system and cause disease. Although infection in human is incidental, the Virus can cause serious neurological disease with high morbidity and mortality. Infection During the first six months of pregnancy may result in infection of the fetus and Miscarriage. JE does not spread from child to child or from cattle to humans because of the low And transient viremia. This is the reason why an increase in cattle and pig ratio may Reduce the risk of JE in humans [mosquito bites are shared by cattle and pigs]. Clinical manifestation The incubation period in man following a mosquito bite varies from 4-14 days. Not all individuals bitten by mosquitoes develop disease. The ratio of overt disease to Inapparent infection varies from 1:300 to 1:1000. Encephalitis due to JE shows a Scattered distribution. The course of disease in man may be divided into prodromal, Acute, late stage and sequele phase. The fatality varies between 20-40 percent, but may Reach over 58 percent. The average period between the onset of illness and death is 9 Days. An etiological diagnosis of JE is based on serological testing using Elisa that Detects specific igm in the CSF or in blood of almost all patients within 4-7 days of Onset of disease. Protective immune response Protection is associated with the development of neutralizing antibodies. Although No internal standard has yet been established, neutralizing antibody titers of 1:10 or more Are commonly accepted as evidence of protection. Treatment Once a person becomes sick with JE, there is no treatment that can be used to cure The patient. Antibiotics do not work against viruses, and no anti virals are effective. Because there is no specific therapy for JE, attention is given to prevention of Complications. Control programs Spraying mosquito habitates with insecticides, use of bed nets, and pig control have Not yielded the desired results. Human vaccination is the only method that has proven Effective in the control of JE. JE IMMUNIZATION Scientific evidence for JE immunization Human vaccination has been the only reliable tool to control JE. Thailand, for Example, for many years attempted to control mosquitoes and to respond to outbreaks, But it was not until JE vaccine was introduced into the country that the incidence of JE Fell dramatically. There is compelling evidence that human immunization is effective for controlling JE. Studies in Korea, Thailand and Japan showed >99% reduction in JE cases after Immunization. JE vaccination in India In the past attempts have been made in India to vaccinate children against JE. However inadequate availability of JE vaccine has limited the campaigns to small Geographical areas. Though there has been a dramatic reduction in the case load Immediately following these vaccination campaigns, however due to lack of sustained Vaccination program there has not been any major impact in controlling the disease. Following sustained JE vaccination in Perambulur district of Tamil Nadu since 1995 and in the high risk villages of Andhra Pradesh since 1999 there has been some Impact in reducing the case load and disease incidence in these areas. Following the massive outbreak of JE in 2005 in the districts of Eastern Uttar Pradesh and adjoining districts of Bihar, Vaccination campaigns were carried out in 11 Highest risk districts of the country in 2006. Children between the age group of 1 to 15 Years were vaccinated with a single dose of SA 14-14-2 vaccine. Summary of JE vaccines available or under development Source; WHO, October 2006 Cumulative district JE vaccination coverage was as follows The second year of the government’s five year strategy targets 23 districts of 9 States. JE vaccination Campaigns kicked off in March 2007 and by July2007, 20 million More children and adolescents were targetted to be immunized against JE. Since during 1997, the mosquito pool from Virudhunagar District was confirmed To be positive for JE virus and the past history had shown that very high number of cases And deaths due to JE were reported in this district. Hence there was every threat to roll Back the virus activities in the younger generation who were not protected now in the Area for JE virus. So, Virudhunagar District was selected for Japanese Encephalitis Vaccination programme during the year 2007. VIRUDHUNAGAR DISTRICT INCIDENCE OF JE YEAR 91 92 93 94 95 96 97 & 98 99 2000 To 2005 2006 2007 No. Of Cases 18 1 11 7 10 48 0 4 0 1 3 No. Of Deaths 8 1 9 7 8 18 0 2 0 1 1 The vaccination was completed in Virudhunagar District during August 2007.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Efficacy ; Safety ; Sa -14-14-2 Vaccine ; Japanese Encephalitis Virus ; Viruthunagar. |
| Subjects: | MEDICAL > Microbiology |
| Depositing User: | Subramani R |
| Date Deposited: | 19 Aug 2017 02:23 |
| Last Modified: | 19 Aug 2017 02:23 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/1475 |
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