In mid-October, 1999, an unusually high number of hepatitis-A cases were reported among individuals residing in Northeast Seattle and Snohomish County. At the same time, the Snohomish Health District reported an increased number of hepatitis-A cases reported among individuals who resided in Snohomish County, but who worked in the Northeast Seattle area. Because the infected individuals had no other identified risk factor for hepatitis A, health department officials quickly suspected the existence of an hepatitis-A outbreak with a common foodborne source located in Northeast Seattle.
To identify the outbreak’s source, health officials developed an epidemiological survey that included the fast food restaurants and groceries stores prevalent in the North Seattle area. Health department officials then contacted all persons with hepatitis A in King and Snohomish County since October 15, 1999 and the food survey was completed. By November 5, 1999, 18 of 21 persons reported with hepatitis A in King County after October 15, 1999, were found to have eaten at one of two Subway Sandwich outlets during the two to six week period prior to the onset of their symptoms. During this same time period, the Snohomish Health District determined that at least six persons with hepatitis A had eaten at one of the two implicated Subway outlets.
Once the likely source of the hepatitis-A outbreak was determined, health department officials performed a case-control study. The results of the initial case-control demonstrated a strong statistical association between eating at Subway during the identified time period and developing a hepatitis A infection. A subsequent inspection by environmental sanitarians found that neither of the implicated Subway outlets had a written hand washing policy, and that employees were not required to document their knowledge of proper hand washing technique. In contrast, the vast majority of fast food restaurants in the area have written hand washing policies, intensive training on proper hand washing techniques, and require employees to sign their initials to a check-off sheet that confirms that their hand were washed hourly and all after bathroom use.
Having confirmed that the Subway outlets were, in fact, the outbreak’s common source, health department officials issued a press release that stated, in part, that:
An ongoing investigation by Public Health suggest that many [hepatitis-A] infections are associated with consuming food form one of two Subway Salads and Sandwiches outlets during the month of September. . . .”If you have eaten at these restaurants during September and are ill with symptoms of hepatitis, you should seek prompt medical evaluation,” said Dr. Alonzo Plough, Director of Public Health – Seattle & King County.
It is estimated that over 40 persons became ill as a result of eating contaminated food sold at the two Subway outlets implicated in the September 1999 hepatitis-A outbreak.