Some consumer watchdog groups and blogs were quick to point out close-by CAFOs (concentrated animal feeding operations) were responsible for the Listeria contamination either through runoff or other means of transport (e.g., using waste as fertilizer). The animal population, according to Food and Water Watch’s 2007 numbers, in Prowers County, CO was calculated to be 44,017 cattle and 137,766 hogs. The human population in 2010 was 12,551, according to the US Census Bureau.
Listeria monocytogenes are not the first bacteria that come to mind if a contamination is due to animal causes, said Dana Johnson in an FE interview. Johnson is brewery and produce specialist at Birko Corp., a Henderson, CO company specializing in germicidal chemicals for the food and beverage industry. For example, an E. coli O157:H7 contamination would likely originate from cattle. Birko was called in to consult on the use of proper chemical treatments to prevent Listeria contaminations. Unfortunately, part of the problem is that HACCP food safety procedures are not yet mandatory for the produce industry, says Johnson.