An outbreak of suspected enterotoxigenic E. coli (ETEC) was investigated by the Idaho Department of Health (the state) and the Southwest District Health Department (SWDH). The suspected outbreak was reported to the investigating agencies by August 31, 2022. The outbreak was given the state ID “2022-076.”

 On August 30, 2022, the Southwest District Environmental Health Department (EH) received a phone call to notify them of a possible foodborne illness outbreak related to a wedding over the weekend. The caller was the father of the groom, who described around 15 people that he knew with diarrhea. On August 31, EH spoke with the groom and received more information. After this conversation, EH notified the epidemiology department, who again called and interviewed the groom about the event, the food, the activities on site, and others known to be ill. The information gathered from the groom over the phone is as follows: 

The wedding took place on August 27, 2022, and dinner was held around 5pm. The event took place at the Mint Barrel Barn and was catered by Horsewood Catering. There were approximately 100-110 guests, and 50-70 of those were ill at the time of the call. Guests came from all over, mainly Ada County, Canyon County, Idaho County, Illinois, Colorado, Pennsylvania, and England. 

Among vendors were also two bartenders, who set up a bar with beer, White Claws, wine, Coke, and bottled water. All drinks were in a cooler with ice from the venue. Other known food was a cake for cutting and pretzel snacks. Dinner food included tri-tip beef (medium-rare and well-done options), garlic mashed potatoes, gravy, cauliflower cheese, salad (ranch and vinaigrette dressing options), huckleberry butter, bread, chicken strips, and fries. Desserts included chocolate covered pretzels, cake pops, and chocolate chip cookies from Albertsons.

The meal was set up buffet-style, with each dish having its own tongs and spoons. The meat remained on heat, and a chef sliced the meat at the end of the table. Guests were offered disposable plates and silverware. There were no hand washing stations on site, and no hand sanitizer was noted near the food. 

The groom was ill with an onset of August 27 at midnight. Other known onsets occurred on August 28 and 29, 2022. Symptoms included abdominal cramping, vomiting, chills, and diarrhea. Some non-ill guests mentioned only eating tri-tip and salad, and at least one other mentioned not eating dairy. Five out of seven vendors that ate on-site fell ill: one bartender, the DJ, two venue employees, and the videographer. EH received photos and a short video of the food setup from the groom.

The bride and groom tossed remaining leftovers after getting sick, but the bride’s father kept some leftovers. The groom had his stool tested through a provider and awaited his results. After the phone call, the department emailed the groom the survey investigation form to distribute to the guests. 

EH spoke with owners of both the venue and catering companies to get details about the event and set up, and to evaluate food storage, handling practices, employee health protocols, and to ask about any ill workers. On September 2, the venue was inspected, and a walk through of the food prep area and cooking area was conducted. EH collected water samples, used to make the ice on site, to test for E. coli and total coliform bacteria. Venue water results came back negative for E. coli and total coliform bacteria.

On September 6, EH performed an on-site visit of the catering company with an epidemiologist from the SWDH and the state EIS officer. Preparation of food items, correct storage and cooking were not able to be observed since catering only occurred on weekends, so a walk-through of the day’s events were discussed/demonstrated. Fridge temperature logs, storage and cleaning practices were reviewed. Staff were knowledgeable about proper food-handling techniques and excluding ill employees. No violations were noted during SWDH’s inspection, and no ill employees or food handlers were identified. Also of note, the catering business served multiple other weddings on the same weekend and no other event was noted to have ill guests. This outbreak appears to have been an isolated incident.

A menu was provided by the groom, and available leftovers were picked up by EH, which included salad, tri-tip, and the cauliflower dish. The salad was unable to be tested. On September 14, the state lab was able to see growth on both the tri-tip and cauliflower plates. Total coliform bacteria and E. coli both saw growth. The lab stated that the growth is not something that is typically seen in food. On November 10, the final report from the state lab was complete, which showed that an ETEC specific PCR test was unable to detect ETEC DNA in the food cultures.

An Epi-survey was provided to the guests to gather information on a possible source, pathogen, and transmission. The epidemiology department defined a confirmed case as a guest who attended the wedding and had lab confirmation of ETEC within two weeks of the wedding; a probable case as a guest who attended the wedding, or who was in close contact to a guest, with clinically compatible symptoms or a positive ETEC test within two weeks of exposure to a lab-confirmed case, and who filled out the survey; and a suspect case as a guest or vendor who attended the wedding and told the groom of their symptoms, who were then reported to epi, but did not complete the survey. Only 71 ill cases responded to the survey. At least 69 cases reported exposures to tri-tip beef and at least 65 reported exposures to cauliflower cheese. 

Stool kits were sent out to multiple guests for stool testing, and only three were returned for testing. The state laboratory could not test these for ETEC and instead ruled out STEC for the samples received. The epidemiology department notified those who submitted stool samples of their negative STEC results. The groom returned to a medical provider for a second time to get a stool culture and GI panel done since the original labs all came back negative, but ETEC was not on the GI panel tested. As of September 8, the groom was unable to provide a stool sample because he was feeling better, and no secondary testing was completed. 

Out of a total of 75 cases, one case was lab confirmed and 74 were considered probable due to exposure and symptoms. Forty-six cases were female (61%). One case was hospitalized and four visited a healthcare provider. Of the human stool samples tested, one tested positive for enterotoxigenic E. coli (ETEC) and negative for all other pathogens. At least one other probable case was stool tested for the wrong pathogens and resulted negative. Of the stool samples submitted directly to the state lab, none were positive for STEC. Cases fell ill between August 28 and September 5, 2022. Symptoms included diarrhea, abdominal cramping, chills, fever, vomiting, and nausea. All exposures would have occurred on August 27, 2022.

The epidemic curve suggested this to be a point source outbreak with no secondary spread identified. All cases attended the wedding on August 27, 2022. No specific food item were identified as the source, as ill persons reported a wide range of food and no non-ill persons responded to the survey. Due to growth being seen on multiple food items, cross-contamination was suspected, and multiple food items may have been the vehicle for transmission. E.coli was the suspected pathogen, as it was identified in a stool sample of an ill guest, grew on samples from food, and matches the symptomology and incubation period captured in the survey results. The suspected mode of transmission was food that was consumed at the wedding. This outbreak was declared over as November 10, 2022.