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Food Poison Journal Food Poisoning Outbreaks and Litigation: Surveillance and Analysis

Just how many Farm Rich E. coli victims are there?

We know that there are 24 infected people in 15 states, 7 who have been hospitalized, and 1 who developed hemolytic uremic syndrome (HUS).  But the reach of Farm Rich’s E. coli tainted chicken quesadillas and possibly other products is certainly broader than that.

There is little doubt that the E. coli illnesses caused by Farm Rich’s products have been underreported.  The concept of underreporting–people sickened in an outbreak for whom, for any of a variety of reasons, microbiological data is not secured to confirm their relationship to the outbreak–is common in E. coli and other outbreaks.  One commentator states, “many cases of foodborne illness are not reported because the ill person does not seek medical care, the health-care provider does not obtain a specimen for diagnosis, the laboratory does not perform the necessary diagnostic test, or the illness or laboratory findings are not communicated to public health officials. Therefore, to calculate the total number of illnesses caused by each pathogen, it is necessary to account for underreporting, i.e., the difference between the number of reported cases and the number of cases that actually occur in the community. For Salmonella, a pathogen that typically causes nonbloody diarrhea, the degree of underreporting has been estimated at ~38 fold (Voetsch, manuscript in preparation). For E. coli O157:H7, a pathogen that typically causes bloody diarrhea, the degree of underreporting has been estimated at ~20 fold.”  See Paul Mead et al. http://www.cdc.gov/ncidod/EID/vol5no5/mead.htm.

In the Farm Rich E. coli outbreak, the CDC apparently agrees, and is concerned that we do not yet know, and may never know, the full scope of the outbreak.

The type of bacteria responsible for this outbreak is among those referred to as Shiga toxin-producing E. coli or STEC. Some types of STEC frequently cause severe disease, including bloody diarrhea and hemolytic uremic syndrome (HUS), which is a type of kidney failure. STEC bacteria are divided into serogroups (e.g., O157 or O121). E. coli O157 is the STEC serogroup found most commonly in U.S. patients. Other E. coli serogroups in the STEC group, including O121, are sometimes called “non-O157 STECs.” Because clinical laboratories typically cannot directly identify non-O157 STEC serogroups, they must first test stool samples for the presence of Shiga toxins. Then, the positive samples must be sent to public health laboratories to look for non-O157 STEC. In recent years, the number of clinical laboratories that test for Shiga toxin has increased greatly, but some laboratories still do not perform these tests. Because of these complexities, many non-O157 STEC infections are probably not identified. The STEC O121 PFGE pattern in this outbreak is rare. In the past it has been seen less than 30 times in PulseNet.

If the information in the Meade article is any benchmark, there are a lot of sick people who have not been identified in the Farm Rich E. coli outbreak.  24 x 20 = 480.