An epidemic of hepatitis A attributable to the ingestion of raw clams in Shanghai, China.
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.
Halliday
M L
ML
Department of Preventive Medicine and Biostatistics, Faculty of Medicine, University of Toronto, Canada.
Kang
L Y
LY
Zhou
T K
TK
Hu
M D
MD
Pan
Q C
QC
Fu
T Y
TY
Huang
Y S
YS
Hu
S L
SL
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000818:Animals; D049872:Bivalvia / Q000382:microbiology*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D005516:Food Microbiology; D006506:Hepatitis A / Q000453:epidemiology* / Q000209:etiology; D006507:Hepatovirus / Q000302:isolation & purification* / Q000648:ultrastructure; D006801:Humans; D007223:Infant; D008297:Male; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D011446:Prospective Studies