Investigating a community-wide outbreak of hepatitis A in India

Abstract

Background:There was an outbreak of acute hepatitis in Mylapore village, Kollam district, Kerala, southern India during February to June 2013. An outbreak investigation was initiated with the objective of describing the epidemiological features of the hepatitis outbreak.Materials and Methods:House-to-house visits were undertaken to identify symptomatic cases. The outbreak was described in terms of person, place and time. Hypothesis was generated based on findings from descriptive study, laboratory investigation of water samples, and environmental observations. A case-control study was designed to test the hypothesis. Chi-square test, univariate analysis, and logistic regression to identify the risk factors associated with hepatitis A infection were done.Results:Line list generated consisted of 45 cases. Attack rate was the highest among the age group 15-24 years (4.6%) followed by 5-14 years (3.1%). The geographical distribution of the cases suggested a clustering around the water supply through the pipeline and epidemic curve showed a sharp rise in cases suggestive of a common source outbreak. Water samples collected form pipeline showed evidence of fecal contamination and absence of residual chlorine. In the case-control study, having consumed water from the pipeline (odds ratio: 9.01 [95% confidence interval: 2.16-37.61]) was associated with the hepatitis A cases.Conclusion:The time frame of disease occurrence, environmental observations, anecdotal evidences, laboratory results and results of the analytical study indicated the possibility of occurrence of hepatitis A outbreak as a result of pipe water contamination supplied from a bore well. The study warrants establishment of an efficient water quality surveillance system.

Seroprevalence of Hepatitis- A virus in North Karnataka and its changes over a 5 year period

“…5 Anti-HAV antibody titre has declined to less than seventy percent in Indian adults owing to the improvement in sanitation and urbanisation . 7 According to ACIP recommendations, prevaccination testing for the presence of anti-HAV antibodies may be considered among populations expected to have high rates of previous HAV infection and natural immunity in order to reduce costs by not vaccinating persons already immune to HAV. An analyses based in Ireland which was cost-effective showed that vaccination is the choice of approach where HAV immunity is 45% or less, and when immunity is greater than 45%, screening followed by vaccination should be performed.…”

“…Preventive measures with vaccination strategies: HAV infected persons can take days to months to return to their daily schedule like schooling or work and this can lead to losses in the society both economically and socially. 7 Hence a vaccination schedule should be included if necessary to reduce this morbidity. People who should be routinely vaccinated with hepatitis A vaccine include all children between their first and second birthdays (12 through 23 months of age) and children and adolescents 2 through 18 years of age who live in states or communities where routine vaccination has been implemented because of high disease incidence.…”

Investigation of Hepatitis A outbreak in Palakkad district

“…18 Evidence from several other studies in Kerala and other areas of India supports the fact that the age of acquiring hepatitis A virus (HAV) infection is shifting from early childhood to adolescence and young adulthood with improvement in economic and living conditions of the communities. 7,11 The strain isolated in the present outbreak was hepatitis A III A genotype. A similar genotype was also reported in an outbreak of viral hepatitis at Kottayam, Kerala during January 2005.…”

“…4 Outbreaks of hepatitis A have been reported from different parts of Kerala over the years. [5][6][7] In India, HAV infection is very common but usually occurs in early childhood. Infection at this age is most often asymptomatic and leads to life-long immunity against reinfection.…”

“…1 Universalizing HAV vaccination could prevent the disease incidence in community, but the cost of vaccine would be a limiting factor. 7 Hepatitis A vaccine can be recommended to susceptible populations in countries with intermediate endemicity.…”