On Tuesday, July 13, 2010, the Estes Park office of the Larimer County Department of Health and Environment (LCDHE) was contacted by several members of the Summer Residents Association (SRA) who had attended a July 12, 2010 group meal at Wild Basin Lodge in Allenspark, Colorado. The members called to inform the health department that numerous people who attended the group meal were reporting illness early Tuesday morning (July 13, 2010) with symptoms of diarrhea, nausea, and abdominal cramps. About 100 people had attended the July 12, 2010 group meal.

Boulder County Public Health (BCPH) and the Colorado Department of Public Health and Environment (CDPHE) were contacted on July 13, 2010 and an investigation into the outbreak was started.

As part of LCDHE’s investigation, they interviewed the SRA members who attended the group meal. Sixty-two people were interviewed. In addition to the SRA interviews, BCPH also interviewed four members from a smaller dinner party who had eaten the same evening at the Wild Basin Lodge, and eighteen employees of the Wild Basin Lodge (eleven of whom had eaten at the establishment on the evening of July 12).

The case definition for illness associated with this event was: “Onset of illness after consuming food at the July 12, 2010 group meal and having 3 or more bouts of diarrhea in a 24 hour period.” Of the 77 individuals interviewed who had eaten food at the Wild Basin Lodge on July 12th, 42 (54.5%) fit the case definition for being ill.

The time until onset of symptoms ranged from 5.5 hours to 35.5 hours, with a median of 9.5 hours. One individual was hospitalized.

Three stool samples were collected from SRA members that attended the group meal. All three stool samples tested positive for Clostridium perfringens toxin. The average incubation period for C. perfringens is 10 to 12 hours, with a range of 6 to 24 hours. “Because of the positive lab results in three members, the incubation time for C. perfringens being consistence with diners illness, and the large number of dinner attendees who became ill after eating at this facility, this outbreak was most likely due to a time and/or temperature abuse of a food contaminated with C. perfringens.”

Although the health department was unable to separate out any one particular food item as the source of illness because most of the people who ate at the buffet consumed most of the food items offered, the health department was unequivocal in its conclusion: “[B]ased on number of people ill, symptoms, onset and duration of illness, and laboratory results, an outbreak of illness caused by C. perfringens can be associated with this event.”

Following the health department investigation, they concluded that fault for the outbreak lies with Wild Basin Lodge:

[I]t is likely that C perfringens spores were introduced to the facility on a food item and perhaps directly into one of the foods prepared by the facility. The key link from spore to bacteria is temperature abuse. Bacteria causes illness (spores do not cause illness), so regardless of the presence or absence of C perfringens, in either vegetative (bacterial) or spore form, if cooking and holding temperature processes are followed, those processes would have prohibited bacterial growth.