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The present study aimed to analyse molecular epidemiological data from hepatitis A virus (HAV) outbreaks in two affected areas. The association between the knowledge of hepatitis A and incidence of infection was also determined. Serum samples were obtained from 88 individuals with clinical manifestations of acute hepatitis in Lamongan (n=54) in January 2018 and Bangkalan (n=34) in March 2018. The outbreak investigation was started one day after the outbreaks were reported by the Public Health Offices in Lamongan and Bangkalan. Anti-HAV immunoglobulin M (IgM) and PCR amplification products of the VP1 capsid protein-P2A protease and VP1-VP3 junctions were analysed. Positive PCR products were sequenced, and a phylogenetic tree was constructed using Molecular Evolutionary Genetics Analysis X software. The control group comprised healthy students and staff members from the two affected areas. Thus, 172 responses from the control and hepatitis A case groups were analysed to assess the association between the students' knowledge level and the incidence of HAV infection. A total of 32 (59.25%) of the 54 individuals from Lamongan and 19 (55.9%) of the 34 participants from Bangkalan were positive for anti-HAV IgM; 26 PCR tests were positive in the VP3-VP1 and/or VP1-P2A junction, which were identified as HAV subgenotype IA. The subtype of HAV in the two areas was IA, similar to those identified previously, but the viruses did not originate from the same strain, as identified by multiple alignment. The knowledge level of the students and staff members in Lamongan studying and working at a half-day school exhibited a significant association with the incidence; however, no association was observed among the students in Bangkalan studying at a full-day school with a dormitory.

Background: Hepatitis A outbreaks were reported by the Lamongan District Health Office to the Surabaya Center for Environmental Health and Disease Control Engineering on January 16, 2018, indicated by an increase in hepatitis A cases in of G and S areas, B village. One of initial sufferer was students in High School X.. Purpose: This study aims to identify the epidemiological characteristics of hepatitis A outbreaks that occur in High School X and the risk factors. Methods: The investigation was carried out in an observational manner with a cross sectional approach. Data were collected by structured interviews, hepatitis A antibodies in blood samples assay, environmental observation, and water samples assay. Data were collected with purposive determination of respondents. Results: Hepatitis A outbreaks at High School X in Lamongan District take place from November 2017 to january 2018, with a target group of 33 students. The epidemic cased tends to be extend common source. Risk factors are contact history with patients, eating habits together in same place, mutual exchange and sharing same eating utensils, the lack of hygiene habit (such as washing hands with soap for students and food handlers), lack of hand washing facilities, bad sanitation, bad food hygiene management, and inadequate clean and hygienis water source. Conclusion: The outbreaks of hepatitis A was extended with the most important risk factors, i.e. lack of personal hygiene and sanitation of water sources.