An epidemic of hepatitis A attributable to the ingestion of raw clams in Shanghai, China

J Infect Dis. 1991 Nov;164(5):852-9. doi: 10.1093/infdis/164.5.852.


An epidemic of hepatitis A in 1988 in Shanghai had an overall attack rate of 4083/100,000 population (292,301 cases). The epidemic curve showed three peaks in January and February. A case-control study of 1208 matched pairs supported that clams were the vehicle for the virus (summary odds ratio, 9.47; P less than .001). Analysis of subsets who had eaten clams indicated that only 3.5% with hepatitis A had cooked their clams compared with 18.1% without hepatitis A, and those with the disease consumed more clams. A historical cohort study indicated that approximately 31.7% of the population had eaten clams one or more times between 9 December 1987 and 3 January 1988. The estimated attack rates in those who had and had not eaten clams were 11.93% and 0.52%, respectively (relative risk, 22.94; attributable risk, 11.41%). The three peaks in the consumption curve correlated with those in the epidemic curve. Hepatitis A virus was demonstrated in clams taken from the Shanghai markets and from the catching area.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Adolescent
  • Adult
  • Age Factors
  • Animals
  • Bivalvia / microbiology*
  • Case-Control Studies
  • Child
  • Child, Preschool
  • China / epidemiology
  • Cohort Studies
  • Disease Outbreaks*
  • Female
  • Food Microbiology*
  • Hepatitis A / epidemiology*
  • Hepatitis A / etiology
  • Hepatovirus / isolation & purification*
  • Hepatovirus / ultrastructure
  • Humans
  • Infant
  • Male
  • Microscopy, Immunoelectron
  • Middle Aged
  • Prospective Studies