Rocky Mountain Natural Meats has recalled approximately 66,000 pounds of bison meat – both ground and steak- in response to at least five linked cases of E. coli O157:H7 in Colorado.   There is another potentially linked illness in New York.

Outbreaks of E. coli O157:H7 in the summer months are nothing new.  Numerous studies have detailed the higher incidence of the potentially lethal bacteria in both humans and animals (ruminants, particularly) in the summer months.  Among these:


  •  A review of E. coli O157:H7 diarrhea in the US by Slutsker et al (1997) found that E. coli O157:H7 was isolated most frequently from patients during the summer months.
  • Results from an epidemiological review of E. coli O157:H7 outbreaks in the US (1982-2002) showed that outbreaks involving ground beef peaked in summer months (Rangel et al, 2005)
  • n a review of non-O157 STEC infections in the US from 1983-2002 revealed that these infections also were most frequent during the summer (Brooks et al, 2005)
  •  In Scotland, HUS and E. coli O157:H7 infections peaked in patients under 15 years of age in July/August, followed by a plateau from June to September (Douglas et al, 1997). Interestingly, the prevalence in Scottish beef cattle at slaughter was found to be highest during the winter, but the concentration of E. coli O157:H7 (number of bacteria shed in cattle feces) was highest during the warmer months (Ogden et al, 2004).

In ruminants (a mammal that digests plant-based food by initially softening it within the animal’s first stomach, then regurgitating the semi-digested mass,  and chewing it again – most commonly cattle, sheep, and goats:

  •  Numerous studies in cattle indicate that fecal shedding of E. coli O157:H7 is typically low in the winter, increases in the spring, peaks during the summer and tapers off in the fall (Edrington et al, 2006; Hancock et al, 2001; Hussein et al, 2005, etc.)
  • Barkocy-Gallagher et al (2003) found that the prevalence of E. coli O157:H7 in cattle feces peaked in the summer, and prevalence on hides (a known risk factor for beef contamination) was highest from spring through fall.
  •  A survey of ground beef samples in the US showed that they were 3x more likely to be contaminated with E. coli O157:H7 from June – September (Chapman, et al 2001)
  • A survey in the UK found that the majority of retail meats that tested positive for E. coli O157:H7 were collected between May and September.

In litigation against producers of meat susceptible to contamination with E. coli O157:H7, we seek to determine what extra precautions (if any) the producers take against the bacteria in the summer months.   Seems better to take those precautions than to be explaining their lack of them to a jury after an outbreak.