Escherichia coli O157 Infection and Hemolytic Uremic Syndrome (HUS), 2013

During 2013, 143 culture-confirmed cases of Escherichia coli O157 infection (2.7 per 100,000 population) were reported. This represents an 8% increase from the median number of cases reported annually from 2003 to 2012 (median, 132 cases; range, 110 to 163 [Figure 3]). During 2013, 64 (45%) cases occurred in the metropolitan area. One hundred seven (75%) cases occurred during May through October. The median age of the cases was 16 years (range, 9 months to 82 years). Twenty-seven percent of the cases were 4 years of age or younger. Fifty (35%) cases were hospitalized; the median hospital stay was 4 days (range, 1 to 31 days). No cases died.

In addition to the 143 culture-confirmed E. coli O157 cases, 139 cases of Shiga toxin-producing E. coli (STEC) infection were identified. Of those, culture-confirmation was not possible in 27, and therefore it is unknown if those were O157 or another serogroup. Among the remaining 112 cases of STEC other than O157, E. coli O26 accounted for 37 (33%) cases, E. coli O103 for 33 (29%), and E. coli O111 for 20 (18%). The median age of the cases was 18 years (range, 11 months to 94 years). Sixteen (14%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 12 days). One case (serogroup O111) developed HUS and died.

Ten E. coli O157 outbreaks were identified during 2013. Five outbreaks were due to person-to-person transmission in daycares, two outbreaks were due to animal contact, 1 outbreak involved foodborne transmission, 1 outbreak involved waterborne transmission, and 1 outbreak was suspected of being due to foodborne transmission, but other transmission routes could not be ruled out. The 10 outbreaks resulted in 46 illnesses (33 culture-confirmed), with a median of 5 cases per outbreak (range, 2 to 9 cases).
In June, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a daycare in Ramsey County. Two culture-confirmed cases were identified.

In July, 3 cases of E. coli O157 infections were associated with swimming at a lake in Hennepin County. A press release was issued at the time.
In July, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a daycare in Ramsey County. Seven cases were identified, including 3 culture-confirmed.

In August, an outbreak of E. coli O157 infections was associated with a restaurant in Olmsted County. Seven cases were identified, including 6 culture-confirmed. While a specific vehicle was not identified, the environmental health investigation suggested that cross-contamination from raw beef to ready-to-eat foods was the likely cause of the outbreak.
In August, an outbreak of E. coli O157 infections was associated with a wedding and private reception held in Nicollet County. Nine cases were identified, including 8 culture-confirmed. One case developed HUS. The lack of cooperation from the wedding organizers limited the investigation, and while foodborne transmission was suspected, other transmission routes could not be ruled out.

In September, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a daycare in Becker County. Two culture-confirmed cases were identified.

In October, 7 cases of E. coli O157 infections were associated with animal contact at a "Pumpkin Patch" business. Three cases were culture-confirmed, and 2 cases developed HUS. Goats and cattle were present at the "Pumpkin Patch," and multiple animal fecal and environmental samples taken from the pumpkin patch tested positive for Shiga toxin 2, indicating the presence of Shiga toxin-producing E. coli.

In October, an outbreak of E. coli O157 infections due to animal contact at a Fall Festival petting zoo occurred. Two culture-confirmed cases were identified, and 1 developed HUS. E. coli O157 with the same PFGE subtype as the human isolates was isolated from calf and goat feces, and environmental samples.

In October, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a daycare in Murray County. Two cases were identified, including 1 culture-confirmed.

In November, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a daycare in Anoka County. Five cases were identified, including 3 culture-confirmed. Two cases developed HUS. The index case in the outbreak reported recent contact with an ill cousin who was identified as a case in the October Murray County daycare outbreak.

Two non-O157 Shiga toxin-producing E. coli outbreaks were identified during 2013. In April, an outbreak of E. coli O26 infections associated with consumption of iceberg lettuce resulted in 5 cases, all laboratory-confirmed. In May, an outbreak of E. coli O103 infections due to person-to-person transmission in a daycare resulted in 3 cases, 2 culture-confirmed.

Hemolytic Uremic Syndrome (HUS)

In 2013, 17 HUS cases were reported. This number is a 31% increase from the median number of cases reported annually from 2002 to 2012 (median, 13 cases; range, 10 to 22). In 2013, the median age of HUS cases was 3 years (range, 1 to 87 years); 16 of the 17 cases occurred in children <7 years of age. All 17 cases were hospitalized, with a median hospital stay of 11 days (range, 3 to 32 days). One adult case died. From 1997 through 2013, the overall case fatality rate among HUS cases was 5.1%. All 17 2013 HUS cases were post-diarrheal. E. coli O157:H7 was cultured from the stool of 16 (85%) cases, and E. coli O111 was cultured from the stool of the remaining case (the fatal case). In 2013, there were 6 outbreak-associated HUS cases.

• For up to date information see:E. coli O157:H7 and HUS
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2013