Gansu Province, Je Epidemiological Characteristics, Sequelae, And The Burden Of Disease Study

Background:The data from the National Notifiable Diseases Reporting System(NNDRS) showed, the incidence, mortality and fatality rates of Japanese Encephalitis (JE) were at the top 10 in the 27 kinds of Class A and B Notifiable Diseases. Compared with the other infectious diseases, JE has serious consequences with high mortality, and severe sequela, which brings heavy disease burden to both families and country. The incidences rate of sequela in the survival JE cases were in the world are about 20%~40%, but there was no sufficient following-up observation.Because the research work of JE and its sequela involves too many fields, with heavy workload and calculation complexity, therefore the study in this field is quite limit, mainly, carried out in a few large cities. Lack of relevant information in the western region, almost has no reports on the sequela and JE disease burden. Therefore, study is urgently needed to fill the blank in this field. Objectives:1. To understand the epidemiological characteristics of JE in Gansu Province.2. To understand the nervous system and mental sequela of JE, and have a better understanding of the serious consequence of Japanese Encephalitis.3. To analysis the disease burden of JE, in order to provide data for disease prevention and control strategy.Contents and Methods:1. Epidemiological characteristicsCollect the data of JE incidence and morbidity from 1958 to 2008 in Gansu Province, analysis the long-term trends of the incidence from 1958 to 2008, and analysis the epidemiological distribution of JE since 1990 in Gansu Province.2. SequelaFollow-up survey were conducted to the lab confirmed JE cases in the year 2005 and 2006 who were confirmed by cerebrospinal fluid or serological IgM JE test At the same time, select the healthy controls according to the standard of with same gender, almost same educational level, and with 3 years of age difference in the same county .3. The disease burdenFirstly, analysis the incidence, mortality and fatality rate of JE in Gansu province in 2006. Then the investigation was carried out on all expenditure items of the patients had paid, including the hospitalization costs, purchase of medicines by theirs elves, transport costs, gift cost and other direct economic cost. At last, calculate the disability adjusted life year DALY of residents in Gansu Province and the high incidence prefectures of JE .due to the death and disability caused by JE. Results:The epidemic data showed a decreased trend of JE in Gansu Province with, a peak every two to three years. The high season of JE is from July to September,About 95% of cases are located in twenty counties in Tianshui, Longnan, and Pingliang . Since the year of 2002, the incidence of JE of the younger children decresed, but the elders' incidence (>45y) increased in Gansu Province.2. This study shows that 49.35% cases had found sequelae (nervous system and mental sequelae) after the discharge from the hospital, 1.5 to 2.5 years after the discharge, followed 55 cases, 47.27% of the survivals had found with at least one kind of sequelae. Among them, 34.55% had nervous system sequelae, 29.63% cases had suffered mental retardation, 77.78% JE patients had suffered memory defects. Adults cases of≥16 years had a higher consequence rate in mental retardation than that of children..3. In 2006, among the 27 identified A and B infectious disease in Gansu Province, JE mortality rate was at the top 3, fatality rate was at first place. The direct economic cost of JE disease is 7807 RMB yuan. In 2006, the direct economic burden of JE cases is 1,264,700 RMB in Gansu Province. In 2006, JE DALY/1000 people is 0.0568.Conclusion:1. Japanese Encephalitis epidemic season was summer in Gansu Province , most of the cases were located in the south-eastern area with a certain time and places. Since 2002, the incidence of the whole population is decreasing, but the incidence rate of adults is increasing.2. 47.27% of the survivals had found with nervous system or mental sequelae. It has been found for the first time that adult JE cases have higher death rate and disability rate than cases of children. the cranial nerve symptoms of part of JE cases after discharge can be recovered, but sequelae of the pyramidal system and extrapyramidal system were difficult recovery fully.3 JE had the high mortality, mortality rate, and patients have to aford the high cost of treatment, JE disease burden can not be underestimated. Fatality rate of the adult JE case was higher than children. 4 With the wild use of JE vaccine for children, adult JE incidence increased cause more and more concerns. Public health departments should consider this issue of adult cases when making JE prevention and control strategy.