Escherichia coli O157 Infection and Hemolytic Uremic Syndrome (HUS), 2014

During 2014, 128 culture-confirmed cases of Escherichia coli O157 infection (2.4 per 100,000 population) were reported. The number of reported cases represents a 6% decrease from the median number of cases reported annually from 2004 to 2013 (median, 136 cases; range, 110 to 163). During 2014, 28 (22%) cases occurred in the metropolitan area. One hundred ten (86%) cases occurred during May through October. The median age of the cases was 22 years (range, 10 months to 88 years). Twenty percent of the cases were 4 years of age or younger. Thirty-eight (30%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 68 days). One case developed HUS and died.

In addition to the 128 culture-confirmed E. coli O157 cases, 173 cases of Shiga toxin-producing E. coli (STEC) infection were identified in 2014. Of those, culture-confirmation was not possible in 23, and therefore it is unknown if those were O157 or another serogroup. Among the remaining 150 cases with STEC other than O157, E. coli O111 accounted for 51 (34%) cases, E. coli O26 for 41 (27%), and E. coli O103 for 34 (23%). The median age of the non-O157 STEC cases was 21 years (range, 6 months to 92 years). Twenty-eight (19%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 68 days). No cases died.

Three E. coli O157 outbreaks were identified during 2014. One outbreak was due to person-to-person transmission in a daycare, one outbreak was due to animal contact, and one outbreak involved foodborne transmission. The three outbreaks resulted in 74 illnesses (43 culture-confirmed), with a median of 15 cases per outbreak (range, 2 to 57 cases).

In July, an outbreak of E. coli O157 infections associated with animal contact at a petting zoo that had traveled to three county fairs and one community festival occurred. Fifteen cases (14 culture-confirmed) were identified, and 2 cases developed HUS. E. coli O157 with the same PFGE subtype as the human isolates was identified in samples collected from a goat, alpaca pen, and an animal trailer.

In July, an outbreak of E. coli O157 infections associated with five events catered by the same company occurred. Fifty-seven cases were identified, including 27 that were culture-confirmed. E. coli O157 with the same PFGE subtype as the human isolates was isolated from potato salad served at three events. Celery from the same shipment was used in the potato salad and was served at the remaining two events at which cases ate.

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

Seven non-O157 STEC outbreaks were identified during 2014. Five outbreaks were due to foodborne transmission and two were due to person-to-person transmission, in daycares. The seven outbreaks resulted in 43 illnesses (34 culture-confirmed), with a median of 4 cases per outbreak (range, 2 to 14 cases).

In April, an outbreak of E. coli O26 infections associated with consumption of romaine lettuce resulted in 4 cases, all culture-confirmed.

In May, an outbreak of E. coli O103 infections associated with consumption of romaine lettuce served at multiple restaurants from the same restaurant chain resulted in 6 cases, 5 culture-confirmed.

In June, 14 cases of E. coli O111 infections were associated with consumption of cabbage served at a multiple restaurants from the same restaurant chain.

In July, an outbreak of E. coli O121 infections associated with person-to-person transmission occurred at a daycare in Todd County. Eleven cases,3 culture-confirmed, were identified.

In October, an outbreak of E. coli O121 infections was identified. Three cases occurred in Minnesota, and additional cases were identified in other states. Leafy greens were determined to be the most likely vehicle.

In November, an outbreak of E. coli O111 infections was associated with consumption of corn salsa served at a restaurant. Three cases, all culture-confirmed, were identified.

In November, an outbreak of E. coli O111 infections associated with person-to-person transmission occurred at a daycare in Stearns County. Two cases, both culture-confirmed, were identified.

Hemolytic Uremic Syndrome (HUS)

In 2014, 10 HUS cases were reported. The number of reported cases represents a 41% decrease from the median number of cases reported annually from 2004 to 2013 (median, 17 cases; range, 10 to 22). In 2014, the median age of HUS cases was 4.5 years (range, 0.2 to 35 years); 6 of the 10 cases occurred in children less than 7 years of age. All 10 cases were hospitalized, with a median hospital stay of 9 days (range, 4 to 69 days). One pediatric case died. From 1997 through 2014, the overall case fatality rate among HUS cases was 5.3%. All 10 HUS cases reported in 2014 were post-diarrheal. E. coli O157:H7 was cultured from the stool of 8 (80%) cases. In 2014, there were 2 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, 2014