Epidemiological Analysis of an Outbreak

Case Study #2: Clostridium perfringens at a BBQ Festival

INTRODUCTION AND BACKGROUND

The case involves an outbreak of a disease that affected 31 people who had returned from a festival, where they had taken a variety of different BBQ products.
The individuals were being treated in 2 hospitals, which then reported the matter to a public health official in the location.
Consequently, the public officer initiated an outbreak investigation of the situation, which mainly focused on interviewing all the ill individuals.

All the ill individuals reported to the two hospitals with severe symptoms of abdominal pain and diarrhea among other symptoms of gastrointestinal infections.
In addition, the investigating team sought to perform a case-control study to determine the actual cause of the illness.
Consequently, the team retrieved credit card receipts from festival ticket sales, from which they were able to contact additional 33 individuals who had gone to the festival but did not get the illness, thus making the total number of the interviewed individuals 64.

After collecting stool samples from the patients at the two hospitals, the outbreak investigators found that the cause of the illness was infection by Clostridium perfringens.
Nevertheless, the team was not able to collect food samples from the site of the festival because the event was nearing its end and all the vendors had completely sold or disposed the food items, which means that it was not possible to test the food items for the causative bacteria.

Noteworthy, Clostridium perfringens is a bacteria and one of the most common causes of food poisoning in the US, causing more than one million infection cases per year.
The bacterium is non-motile, anaerobic and spore forming cell with a capsule on the surface. In addition, Clostridium perfringens cells are rod-shaped and vegetative (Finsterer & Hess, 2007).
They occur in pairs or short chains. When exposed to catalase and superoxide dismutase, the cells do not react with the enzymes, meaning that they are catalase and dismutase negative (Acheson, 2011).

More important, Clostridium perfringens cells have 5 toxigenic types (A, B, C, D and E), with both A and C strains being pathogenic to humans (Finsterer & Hess, 2007).
A number of different toxins are produced from these cells, causing infections in the human GIT. When the cells are cultured at 37OC, double zones of hemolysis are produced on a blood agar media overnight (Acheson, 2011).

The bacterial infection with Clostridium perfringens has been affecting people in the US over the years. In the recent past, several outbreaks have been reported I various states. For instance, on October 22, 2015, an outbreak was reported in Iowa, specifically at Iowa High School (Acheson, 2011).

Investigators found that the outbreak followed a catered staff luncheon at Roosevelt High School in Des Moines, with at least 58 people falling ill and classes cancelled for at least one day.
County and state health officials found that the cause of infection was Clostridium perfringens, which had infected meat served at the luncheon.

In the State of Maryland, a similar outbreak was reported in 2014, with 216 out of the 1,300 delegates attending a conference in Baltimore falling ill with symptoms of diarrhea, nausea and vomiting (Acheson, 2011).
The Maryland Department of Health and Mental Hygiene found that a chicken masala dish had been contaminated with

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