In early December of 2000, the Lake County Health Department (LCHD) in Florida learned of seven hepatitis A cases, including five hospitalizations, in Lake and neighboring Sumter Counties in a two week span. LCHD notified the Florida Department of Health of a possible hepatitis A outbreak.
LCHD, the Florida Bureau of Epidemiology, and the Florida Bureau of Environmental Epidemiology, Food, and Waterborne Disease began a case study to attempt to determine the source of the outbreak. A case was described as:
[A] positive hepatitis A IgM antibody test in a Lake or Sumter county resident who had elevated liver enzyme tests or an acute onset of jaundice or abdominal pain, onset of illness between November 10 and December 16, 2000, and no other explanation for the elevated liver tests or abdominal pain.
Known “cases” were interviewed, and in an effort to locate unknown “cases,” the investigation team contacted area health care facilities and labs, known visitors to Lake County during the outbreak period, and known “case” family members and acquaintances who had experienced similar symptoms. Investigators also contacted the business acquaintances and contacts of those known cases who worked in the food and childcare industries. Twenty-one cases were identified.
Investigators then conducted two case-control studies. The first aimed to determine the source of the outbreak, and ultimately revealed a strong association between cases and the consumption of food from the Taco Bell restaurant in Fruitland Park, Florida. Consequently, serologic testing was done on all Taco Bell employees who had worked during the exposure period. Other than the individual who was a known case, the employees tested negative.
The second case-control study was conducted to identify the Taco Bell food item(s) that were, or had been, contaminated. Six meal items and eight ingredients were significantly associated with illness. Of the meal items, only two were eaten by a majority of cases. And of the eight ingredients, green onions carried the strongest statistical association. Further analysis revealed that the green onions were the most likely vehicle for transmission.
While the Lake County investigation was ongoing, the LCHD learned from the CDC that hepatitis A outbreak investigations were also underway in Russell County, Kentucky and Clark County, Nevada. Taco Bell green onions would soon be implicated in these outbreaks as well.
LCHD and other investigators ultimately identified twenty-three people who met the case definition and were confirmed to have suffered a hepatitis A infection. In total, fifteen cases (65%) required hospitalization due to the severity of their symptoms.
The CDC conducted laboratory testing on serum collected from cases in Florida, Kentucky, and Nevada. Testing revealed a connection between the three outbreaks, and LCHD further concluded that “[a]lthough most foodborne outbreaks of hepatitis A are due to food contaminated by an infected food preparer, we believe the ingredients were contaminated prior to arrival at the outlet in this outbreak. . . . The most likely contaminated ingredient is green onion.”
Marler Clark represented four clients in claims against Taco Bell after they became ill with hepatitis A infections. The firm resolved all four claims in the spring of 2006.