| Summary: | An epidemic of viral hepatitis type A in an arctic area is described. From 1970–1974, 4961 clinical cases of hepatitis were reported in Greenland, corresponding to 11 per cent of the total population. Epidemiologic surveillance indicated person-to-person transmission of the disease, apparently by the oral-fecal route. The course of the disease was mild, and complications were rare with a case fatality rate of 0.3%. Ninety-three per cent of the cases occurred in individuals 1–25 years of age, suggesting widespread immunity in the adult population presumably due to infection with hepatitis A during a similar epidemic in 1947–1948. The occurrence of antibody to hepatitis A antigen (anti-HA) in healthy Greenlanders, as detected by radioimmunoassay, closely paralleled this observation. Anti-HA was present in 38 (93%) of 41 individuals born before 1948 and in one (3%) of 29 younger persons. Anti-HA also was detected during the epidemic in the sera of 25 randomly selected hepatitis cases. Immunoglobulin analysis in three acute-phase sera showed anti-HA reactivity predominantly in the IgM fraction. The epidemic showed no relation to the hepatitis episodes occurring annually in the area, and sero-epidemiologic data indicated that the endemic hepatitis may be caused by hepatitis B virus only.
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