In Minneapolis, 107 cases of hepatitis A were identified and traced primarily to consumption of cold sandwiches served for lunch in a department store's popular basement restaurant. A sandwich-maker in the restaurant was the index patient. The date of onset of her illness and the dates of food consumption and onset of illness of infrequent restaurant patrons were consistent with accepted periods of infectivity and incubation for hepatitis A. Because the sandwich-maker frequently touched her hands to her mouth when she worked, and because we could not find evidence for fecal, airborne, or other modes of transmission, we believe that she may have contaminated food with infectious oropharyngeal secretions. The secondary attack rate was much lower among household contacts who received immune serum globulin than among those who had not.
(JAMA 234:289-294, 1975)
Levy BS, Fontaine RE, Smith CA, Brinda J, Hirman G, Nelson DB, Johnson PM, Larson O. A Large Food-Borne Outbreak of Hepatitis APossible Transmission Via Oropharyngeal Secretions. JAMA. 1975;234(3):289–294. doi:10.1001/jama.1975.03260160037009