Affiliations: *FETP Division of Epidemiology, Ministry of Public Health
**Hepatitis virus Section, National Institute of Health, Ministry of Public Health
Source: Journal of Health Science July-August 2002; 11(4): 452-9
Language: Thai with English abstract
A cluster of suspected viral hepatitis A case were reported in a suburban district. An investigation was conducted under a combination of a descriptive study and an analytic one. There were 25 confirmed cases; their median age was 14 years (range 6-31 years). Nineteen cases were males. The onset of symptomatic cases fall within one incubation period (15 July to 31 Augusts, with peak during 25-30 July). Most cases found in one village (AR = 53.6 cases/1000 population). Based on logistic regression, the possible risk factors for infection were the use of piped supply water from system A or B (OR = 3.76, 95%CI 1.04-20.15). Fed by artesian wells (closed systems, 100 meters deep), seven water supply systems serviced the area without disinfection process. HAV RNA was found in water in reservoir tanks of system A and B, and in containers of four households supplied by the both systems. Although without proof for temporal ambiguity, the epidemiological and environmental finding suggested that contamination of piped water by hepatitis A virus was the possible cause of the outbreak. The contamination of two pipeed-water systems at the same time suggested underground leakage to be thoroughly checked and duly repaired.