The Cedar Heights Church in Cedar Falls, Iowa hosts an annual Thanksgiving dinner that is open to all church members as well as the general public.

The 2004 dinner was prepared and delivered to the church by the Hy-Vee grocery store located on University Avenue in Cedar Falls, Iowa. The consisted of turkey meat, dressing, mashed potatoes, gravy, green beans, cranberry sauce, coffee, milk, lemonade, rolls, and butter. Approximately 750 meals were served at the dinner, including approximately 140 delivered to homes by church volunteers.

The first report of illness came on the morning of Monday, November 29, 2004. The Black Hawk County Health Department received a complaint from a mother and her two children that they experienced watery diarrhea, vomiting, and cramps approximately ten hours after consuming the church-provided meal. Based on this information, the health department initiated an outbreak investigation and contacted the Iowa Department of Public Health’s Center for Acute Disease Epidemiology for assistance.

The investigation team interviewed both ill and healthy patrons of the church dinner. From the lists provided by the church and information acquired during telephone interviews, 56 individuals were identified as attending the event, and another 56 individuals were identified as receiving home delivered dinners. The investigation team collected information on signs and symptoms of illness, onset times of illness, foods eaten, and whether they ate their dinners at home or at the church.

After the investigation team had concluded the interview process, questionnaires were analyzed from 110 individuals that had either attended the church dinner or received a home meal from the church; 58 of the 110 met the case definition for ill. The investigation team documented the following symptoms and their frequency in the ill cases:

•Diarrhea – 89.5%
•Abdominal cramps – 79.3%
•Nausea – 43.1%
•Vomiting – 27.6%
•Headache – 24.1%
•Chills – 24.1%
•Muscle aches – 21.1%
•Fever – 5.2%

On Tuesday, November 30, the Health Officer from Black Hawk County met with various employees at the Hi-Vee grocery store that prepared the turkey dinners. In an interview with the Deli Manager, details were discovered regarding the preparation of the turkey meat used in the dinner. The breast meat was received frozen at approximately 4:00 p.m. on Monday, November 22. The breast meat was placed in the walk-in refrigerator to thaw. The thigh meat was not received frozen and therefore did not require thawing. On Wednesday, November 24, the breast and thigh meat was baked in accordance with the directions of the manufacturer, Willow Brook Foods. As such, the turkey meat was baked in a convection oven at 350º for 2 ½ to 3 hours, “to an internal temperature of 160º”. The meat was then placed in the cooler overnight.

There was some confusion regarding the length of time the turkey was actually cooked, however. One employee stated the turkey was cooked in the convection oven for 2 ½ to 3 hours until it reached an internal temperature of 160º, as directed by the manufacturer. Conversely, in the field investigation notes of investigator Jon D. McNamee, it states that “the product is kept frozen, then slacked to a ½ frozen state. They are panned 8 to a pan and placed in a 350º oven for 1 ½ to 1 ¾ hour to an internal temp of 160º.” Notably, under either scenario, the turkey was only cooked to an internal temperature of 160.

On the issue of proper cooking times, the health department noted in it’s final report that cooking the turkey to an internal temperature of only 160º was in violation of the Iowa Food Code. “The processor’s finished temperature requirements for this product are not in compliance with Section 3-401.11(3) of the Iowa Food Code which states that poultry shall be cooked to 165º or above for 15 seconds.”

On the day of the event, the turkey meat was taken out of the cooler, sliced, placed on disposable aluminum pans, and the placed back in the convection oven to cook at 350º for approximately 1 hour, to an internal temperature of 165º. The meat was then placed in the hot-hold deli cases. At about 10:00 a.m., the first of three shipments of the meat was moved from the deli cases, covered with cellophane and foil, and placed in plastic food carriers for transport to the church.

It was reported to the investigators that stem thermometer readings of the turkey meat were taken throughout the preparation and holding process. However, it is important to note that no documentation of these temperatures was kept.

Due to the large amount of food being prepared, three deliveries were made to the church on November 25. Deliveries were made from Hy-Vee to the church at 10:30 a.m., 12:00 p.m., and 2:00 p.m. Church volunteers served the meals directly from the holding units they were received in to the event attendees. Many of the same volunteers also apportioned the meals into Styrofoam containers for those receiving home delivery meals.

During the investigation a number of food samples were obtained. Some samples were obtained from the Hy-Vee store, while others came from attendees who had leftovers in their home. After laboratory analysis, it was determined that the turkey meat contained a high number of Clostridium perfringens (4.3 x 105), total and fecal coliforms, and a high aerobic plate count. The laboratory interpretation was as follows: “Criteria used by the CDC to identify an outbreak include isolation of 105 C. perfringens from the epidemiologically implicated food. Even though the turkey was not epidemiologically implicated (statistics not significant), the presence of high numbers of C. perfringens, total and fecal coliform, and high aerobic plate count in a cooked product supports the hypothesis that the product was highly contaminated (indicators of cleanliness). Since the symptoms were consistent with C. perfringens type A food poisoning and C. perfringens type A organisms were isolated from the turkey in significantly high numbers, this food product likely contributed to the outbreak.”

Based on the results of the epidemiological and environmental investigations, the health department concluded that C. perfringens was the most likely cause of the church turkey dinner outbreak. “Laboratory and clinical evidence in this case appears to point to Clostridium perfringens as the most likely causative agent. In most instances, the actual cause of poisoning by C. perfringens is temperature abuse of prepared foods. Small numbers of the organism are present after cooking and multiply to infective levels during the cool down and storage of prepared foods.”

Following the interviews with store employees, and the ensuing media coverage surrounding the outbreak, local health officials were informed of a similar outbreak at the Ryder Truck Company business establishment, following a Thanksgiving holiday event also catered by the University Avenue Hi-Vee grocery store. Seventeen individuals who ate food served at the Ryder event became ill as a result of eating the turkey dinner prepared by Hi-Vee. The event showed obvious similarities with the church event in menu items, symptoms, and time of onset.

This outbreak was also investigated by the Black Hawk Health Department. Its environmental investigation concluded as follows: “The most plausible hypothesis for the Business A outbreak is that the turkey was cooked and stored at inappropriate temperature, which allowed for rapid development of Clostridium perfringens.”

Again, as with the church event outbreak, the health department concluded as follows: “This case appears to point to Clostridium perfringens as the most likely causative agent.