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The role of dairy cattle in human infections with Shiga toxin-producing Escherichia coli (STEC) has emerged in the past two decades. A large number of outbreaks and sporadic cases of human illnesses resulted from visiting dairy farms or consumption of raw milk, dairy products, or ground beef from culled dairy cows. The illnesses included mild or bloody diarrhea, vomiting, abdominal pain, hemorrhagic colitis, and the life-threatening hemolytic uremic syndrome (HUS). The objective was to determine STEC prevalence in four dairy farms (averaging 713 Holstein cows and heifers) in California during winter and spring. Fresh fecal samples were collected from 532 cows and 73 heifers. Over the two seasons, STEC were recovered in all farms with prevalence rates ranging from 0.6 to 4.1%. Prevalence of STEC was not altered (P > 0.05) by season, parity, or days in milk (1 to 60, 61 to 150, or 151 d). The corresponding prevalence rates averaged 2.0, 1.5, and 1.3%, respectively. Heifers tended to have a higher (P = 0.17) prevalence rate of STEC than cows (5.5 vs 1.5%). The STEC isolates belonged to five serotypes (E. coli O15:H- [a nonmotile isolate], O127:H19, O136:HUT [an untypeable H antigen], OUT [an untypeable O antigen]:H-, and OUT:HUT). Of these STEC serotypes, one (E. coli OUT:H-) is known to cause HUS and two (E. coli O15:H- and OUT:HUT) are known to cause other human illnesses. The E. coli O127:H19 serotype detected in this study has not been reported in cattle. Interestingly, E. coli O157:H7 isolates were not found in the cattle tested. The results of this study emphasize the importance of testing dairy cattle for STEC, in general, and suggest the need for developing pre-harvest control methods to decrease carriage and fecal shedding of these foodborne pathogens. [ABSTRACT FROM AUTHOR]

In the past 25 years, many human illness outbreaks have been traced worldwide to consumption of undercooked ground beef and other beef products contaminated with Shiga toxin-producing Escherichia coli (STEC). Because of the global nature of food supply, the safety concerns with beef will continue and the challenges facing the beef industry will increase. To be prepared to address these concerns and challenges, it is critical to assess the beef cattle role in human infection with STEC. Because most STEC outbreaks in the US were traced to beef containing E. coli O157:H7, the epidemiological studies have focused on prevalence of this serotype in beef cattle. Worldwide, however, additional STEC serotypes (e.g., members of the O26, O91, O103, O111, O118, O145, and O166 serogroups) have been isolated from beef and caused human illnesses ranging from bloody diarrhea and hemorrhagic colitis to the life-threatening hemolytic uremic syndrome (HUS). To provide a global assessment of the STEC problem, published reports on beef and beef cattle in the past three decades were evaluated. Prevalence rates of E. coli O157 ranged from 0.1 to 54.2% in ground beef, from 0.1 to 4.4% in sausage, from 1.1 to 36.0% in various retail cuts, and from 0.01 to 43.4% in whole carcasses. The corresponding prevalence rates of non-O157 STEC were 2.4 to 30.0%, 17.0 to 49.2%, 11.4 to 49.6%, and 1.7 to 58.0%, respectively. Of the 161 STEC serotypes isolated from beef products, 43 were detected in HUS patients and 36 are known to cause other human illnesses. With regard to beef cattle, prevalence rates of E. coli O157 ranged from 0.3 to 19.7% in the feedlot and from 0.7 to 27.3% on pasture. The corresponding prevalence rates of non-O157 STEC were 4.6 to 55.9% and 4.7 to 44.8%, respectively. Of the 350 STEC serotypes isolated from cattle feces or hides, 63 were detected in HUS patients and 61 are known to cause other human illnesses. The results indicated prevalence of a large number of pathogenic STEC in beef cattle and their products at high rates and emphasized the critical need for control measures to assure beef safety. [ABSTRACT FROM AUTHOR]

Since the first outbreak of Shiga toxin-producing Escherichia coli (STEC), the role of beef in human infection has been emphasized. In the US, E. coli O157:H7 has been the STEC commonly associated with human illnesses ranging from diarrhea to the life-threatening hemolytic uremic syndrome (HUS). Worldwide, a large number of STEC serotypes have caused similar illnesses. The objective was to assess STEC prevalence in four cow/calf operations on pasture (ranging from 38 to 1,300 cows) and five on the range (ranging from 65 to 225 cows) in California during winter and spring. Fecal samples were collected from 319 cattle on pasture and 365 on the range. Prevalence rate of STEC was not affected (P > 0.05) by season for cattle on pasture (averaging 3.8%) but was higher (P < 0.05) in winter than in spring for those on the range (13.6 vs 0.6%). Across operations and seasons, calves had a higher (P < 0.05) STEC prevalence rate than cows (12.4 vs 2.3%). Cattle on pasture had a lower (P < 0.05) STEC prevalence rate than those on the range (3.8 vs 7.7%). The STEC isolates belonged to 16 serotypes (E. coli O26:HUT [an untypeable H antigen], O86:H2, O111:H16, O125:H2, O125:H16, O125:H19, O125:H- [a nonmotile isolate], O127:H2, O127:H19, O128:H16, O146:H21, O166:H2, OUT [an untypeable O antigen]:H2, OUT:H16, OUT:H-, and OUT:HUT). Of these serotypes, five (E. coli O26:HUT, O125:H-, O146:H21, OUT:H2, and OUT:H-) are known to cause HUS and two (E. coli OUT:H16 and OUT:HUT) are known to cause other human illnesses. Eight of the serotypes (E. coli O86:H2, O125:H2, O125:H16, O125:H19, O127:H2, O127:H19, O128:H16, and O166:H2) detected in this study have not been reported in cattle. Interestingly, E. coli O157:H7 isolates were not found in the cattle tested. The results of this study illustrate grazing beef cattle as a reservoir of a wide range of STEC of which several serotypes are pathogenic to humans. Thus, it is critically important to develop and implement control measures to decrease carriage and fecal shedding of these foodborne pathogens by beef cattle. [ABSTRACT FROM AUTHOR]