A Large-scale Population Survey Of Hepatitis B Epidemic Status And Its Influencing Factors In Wuwei City, Gansu Province

Background:Hepatitis B is a serious public health problem throughout the world. It is eastimated up to350millon people are chronic HBV infection, and1millon of them died of chronichepatitis, cirrhosis, and hepatocellular carcinoma each year. China is a high prevalent areaof HBV infection. It is estimated that there are93million HBsAg carriers and25millionchronic HBV infected people in China according to the2006National HBVseroprevalence survey results. Hepatitis B is one of the most common infectious diseasesin northwest China, which took account for43%of the notifiable infectious case reports. Wuwei City, Gansu Province, is located in the eastern end of the Hexi Corridor, the totalpopulation of200million, is a traditional agricultural areas. Over the years, the the WuweiCity hepatitis B reported incidence was very high. From year2005to2009, the averagenational hepatitis B reported incidence of hepatitis B was85.26/100000for China,230.28/100000for Gansu Province,743.63/100000for Wuwei City. However, The realprevalence of HBV in Wuwei city and the risk factors were still unkown.Objective:Wuwei City was chosen as the hepatitis B prevention and control demonstration zones andepidemiological study site in2009as a part of the national "Eleventh Five-Year". Thisstudy described a population-based study designed to determine the HBV infectionbaseline rates in Wuwei City and explored the risk factors associated with HBV infection,provided clues and evidence for the prevention and control of HBV transmission.Methods:1. A stratified random cluster sampling was used according to the proportions of eachsection. There are4administrative divisions: Liangzhou District, Gulang County, MinqinCounty, and Tianzhu Tibetan Autonomic County. Each region consists of urban and ruralpopulations. The Wuwei population was divided into8sections according to4administrative divisions characteristic with urban or rural populations. House to houseinvestigations were conducted by trained, local centers of disease control (CDC) staffmembers between February2010and September2010. ELISA kit for the detection ofhepatitis B virus infection serum markers, including HBsAg, anti-HBs and anti-HBc. TheIFCC rate was used for the detection of alanine aminotransferase (ALT).2. All data used Epidata3.1software double entry, and SAS9.2(SAS Institute, Cary, NC,USA) software Compare module was used for data consistency and accuracy verification.Standardized weighted rate and standard error were caculated by linear SURVEYFREQTaylor series method. SURVEYLOGISTIC module was used for single-factor andmulti-factor weighted logistic regression analysis. Enumeration data was caculated by thechi-square test, measurement data was caculated by analysis of variance, and the rate ofchange with the hierarchical change trend was analyzed by trend chi-square test. Statistically significant difference boundary value was set as P <0.05.Results:1. The serological surveys investigated a total of28,044ordinarily resident in Wuwei City,the crude HBsAg positive rate was7.31%, the standard rate was7.19%; anti-HBs positiverate was47.82%, standard rate was43.89%; and crude anti-HBc positive rate was42.33%,the standardized rate of49.07%. The crude positive rates of HBsAg and anti-HBc weresignificantly higher than the national average rates investigated in2006, and anti-HBspositive rate below the national average rate.2. The characteristics of epidemiological distribution: HBsAg positive rate was7.91%formen, and6.84%for women（P <0.0001）; HBsAg positive rate among1-14years oldgroups was significantly lower than the populations of the age of15-59and≥60; HBsAgpositive rate was10.60%for male20-54years old group,20-24years old group was up to11.52%; HBsAg positive rate was higher in Han (7.40%) than the minorities (5.89%)(P<0.05), rural areas (7.64%) than in urban areas (6.12%)（P <0.0001）. Among childrenaged1years,66.55%was anti-HBs positive, whereas among children aged2,3, and4years, the rates were54.22%,49.27%and39.32%, respectively. The anti-HBc positiverate of1to4years old was16.61%,12.44%for the age group of5-9, and increased to59.42%for age group>70. The suspected case rate of hepatitis B was2.35%in WuweiCity. The proportion of hepatitis B susceptible populations was up to33.96%in WuweiCity, and most of which were in20-59age groups.3. Multi-factor weighted logistic regression analysis showed that the close contact historyin family (OR=2.6,95%CI:2.3-3.0), a history of traumatic beauty (OR=1.2,95%CI:1.1-1.3) and surgical history (OR=1.2,95%CI:1.1-1.3) were risk factors of HBVinfection in whole population. The close contact history in family (OR=3.8,95%CI:2.2-6.5) and unvaccinated hepatitis B vaccine (OR=2.0,95%CI:1.4-3.3) were the riskfactors for HBV infection in children aged1-14years.Conclusions:1. Wuwei City is still a high prevalent area of HBV infection, the infection rate was higherthan the national average level. The HBsAg positive rate of Wuwei City was higher in male than female, Han than the minorities, rural areas than in urban, which may beassociated with HBV exposure opportunity, human susceptibility, and hepatitis Bvaccination extensive degree.2. The suspected case rate was high, the Government should further increase investment,and reduce the economic burden of hepatitis B patients.and the proportion of susceptiblepopulation was still high in Wuwei City, hepatitis B vaccination in adults should bestrengthened.3. In addition to strengthen the hepatitis B vaccination, to strengthen the medical devicedisinfection of medical units and traumatic cosmetic process is also an important measureto prevent hepatitis B infection in Wuwei City.