2004 Outbreak of E.Coli
O157:H7 at a
Speaker: Brant Goode, BSN/RN, MPH
Epidemic Intelligence Service Officer
CDC, assigned to NC Div of Public Health
Level of Knowledge: Multi-Level
Background: E. coli O157:H7 and other enterohemorrhagic
E. coli (EHEC) infections cause hemorrhagic colitis and hemolytic uremic syndrome (HUS). An estimated 73,000 EHEC related
infections and 61 deaths occur annually in the
Methods: We conducted a matched case-control study among fair visitors using randomly recruited controls who purchased tickets in advance. We defined cases as persons with culture-confirmed E. coli O157:H7 infection, HUS, or bloody diarrhea with illness onset after visiting the fair. Clinical specimens and environmental samples were tested by culture and pulsed-field gel electrophoresis (PFGE).
Results: Of 108 reported cases, we enrolled 45 confirmed or probable case-patients and 188 controls in the case-control study. Median case-patient age was 3.2 years (range: 1-61). Thirty-six case-patients (80%) reported visiting the same petting zoo (Odds Ratio [OR]:7.7, 95% Confidence Interval [CI]:3.5-17.0). Among visitors to this petting zoo, illness was associated with stepping in or touching manure (OR: 4.9, CI: 1.9-12.8), falling or sitting on the ground (OR: 3.4, CI: 1.3-8.6) or contact with sheep or goats’ front legs (OR: 2.5, CI: 1.03-5.9). Hand hygiene upon exiting the petting zoo was not protective (OR: 1.7, CI: 0.5-5.8). Of 38 patient isolates, 33 (87%) had indistinguishable PFGE patterns. Environmental isolates from the petting zoo area were indistinguishable by PFGE from these 33 clinical isolates.
Conclusions: In this study, most illnesses were associated with animal or manure contact in a single petting zoo. Hand hygiene was not protective. Contact with animals and manure in petting zoos should be restricted to prevent EHEC infections.