The E. coli O157:H7 outbreak in Belgium, Wisconsin has sickened at least 6 kids (one who developed HUS) seems to have several well-defined epidemiological circumstances that may help the State of Wisconsin Health Department identify a source. The victims seem to all be kids, the kids all come from the same relatively small part of the town, and the kids apparently do not interact socially.
Whatever the ultimate significance of these circumstances, another highly interesting epidemiological point in the outbreak is the apparent presence of Cryptosporidium and Clostridium difficile infection among the outbreak cases.
Clostridium difficile
Clostridium difficile (C. difficile) is a spore-forming, gram-positive anaerobic bacillus that produces two toxins: toxin A and toxin B. These toxins typically cause gastrointestinal disease, often with severe complications. In rare cases, C. difficile-associated disease can be fatal. Although C. difficile bacteria can be present in human intestinal tracts and cause no clinical symptoms (a condition called colonization), some individuals with C. difficile colonization are at increased risk of becoming ill. The most common risk factor for C. difficile-associated disease is exposure to antibiotics, especially those with broad-spectrum activity. Although less common, exposure to agents that suppress the immune system may also increase the risk of illness. Advanced age, severe underlying illness, gastrointestinal surgery, use of nasogastric tubes, and gastrointestinal medications (such as gastrointestinal stimulants or antacids) have also been associated with an increased risk of colonization. Most cases are acquired in hospitals or nursing homes, but an increased incidence of community–acquired C. difficile has been reported as well. Recent studies indicate that C. difficile can also be found in food products, thus raising a significant question: Can C. difficile cause foodborne illness?
Sources and Transmission
C. difficile is shed in feces. Any material, device, or surface that becomes contaminated with feces—such as toilets or bathing tubs—may serve as a reservoir for C. difficile spores. The ability of C. difficile to form spores is thought to be a key feature that enables the bacteria to persist in patients and the physical environment for long periods of time, thereby facilitating its transmission.