Northwest Fairgrounds E. coli O157 Outbreak Lawsuit - Washington (2015)


In April 2015 Whatcom County Health Department (WCHD) along with the Washington Department of Health (WDOH) and the Centers for Disease control and Prevention (CDC) investigated an outbreak of E. coli O157:H7 infection occurring among persons who visited the Northwest Washington Fairgrounds.  Approximately 1300 school children from most of the seven school districts in Whatcom County attended the Milk Makers Fest held between April 21 and April 23.  All of the ill people either attended the Milk Makers Fest, helped with the event between April 20 and April 25; or were close contacts of people associated with the event. Most of the ill people were children including older children who helped with the event.

 

Disease investigators based case counts based only on lab-confirmed infection with E. coli O157:H7 or physician diagnosed hemolytic uremic syndrome (HUS). In total there were 25 people laboratory confirmed with E. coli O157.  Nine of the laboratory confirmed cases did not attend event but had close contact with someone who did attend. Ten people were hospitalized. Six people developed HUS. No one died. In addition to confirmed cases, investigators identified 34 probable case patients. Of these, 23 were case-patients who attended the Milk Makers Fest and 9 were secondary case-patients who acquired their infection through contact with someone who did attend.  Dates of illness onset for primary cases ranged from April 22 to May 3.  Secondary cases were reported beginning April 25 through May 25.  Genetic testing by Pulsed Field Gel Electrophoresis (PFGE) showed that laboratory confirmed patients were infected with an indistinguishable strain identified as PulseNet Pattern Combination EXHX01.0047/EXHA26.0071.

 

Investigators interviewed persons involved with the Whatcom Youth Fair, an event preceding the Milk Makers Fest. Beef and dairy cattle were exhibited at the Youth Fair. Youth Fair organizers cleaned the fairgrounds after their event. A scraper was used to move bedding (sawdust) to the manure bunk and a leaf blower was used to move remaining sawdust. Set up for the Milk Makers Fest began approximately 10 days later. Volunteers set up stations including bleachers and the hay maze. The location of some of the Milk Makers Fest stations coincided with the locations where dairy cattle were shown during the Youth Fair.

 

Multiple samples from the environment where the event was held were collected on two different days (April 30 and May 13) and submitted for laboratory testing. The samples indicated that several areas of the north end of the Dairy Barn at the Northwest Washington Fairgrounds were contaminated with the same genetic strain of E. coli O157 that made people ill.  The outbreak strain of E. coli O157:H7 was identified in the following areas of the Dairy Barn:  manure bunker, hay maze area, bleachers by the east wall, and bleachers by the west wall.  Contamination of the environment most likely occurred before the Milk Makers Fest.

 

A case-control investigation was conducted among Milk Makers Fest participants to identify risk factors for E. coli O157:H7 infection at this event. Contact information for cases and controls was provided by public and private schools to Whatcom County Health Department investigators.  Three controls were recruited for each case. Controls were frequency-matched with cases in three groups: 1) individuals who helped to set up the event on April 20, 2015 or dismantle the event on April 24, 2015; 2) first grade students who attended the event between April 21, 2015 and April 23, 2015; and 3) adults who attended the event between April 21, 2015 and April 23, 2015.  By June 11, 2015 public health investigators had interviewed 31 case-patients and 95 controls.

 

Univariate analysis of risk factors for infection with E. coli O157:H7 among Milk Makers Fest attendees showed that children who reported always biting their nails were significantly more likely to become ill than children who reported almost always, sometimes or never biting their nails (Odds Ratio 5.31; 95% Confidence Interval 1.35, 22.45). Participants who reported washing or sanitizing their hands before eating lunch were significantly less likely to become ill, compared to participants who did not wash or sanitize their hands before lunch (Odds Ratio 0.21; 95% Confidence Interval 0.06, 0.62). Exposures that were not associated with illness included previous farm animal exposure, visiting the petting zoo, and drinking chocolate milk.

 

            These findings led investigators to conclude that exiting the dairy barn, which would be considered an “animal area” and therefore contaminated, without hand washing contributed to an increased risk of transmission of E. coli O157:H7 among Milk Makers Fest attendees. They also noted that eating in animal areas contributed to an increased risk of transmission of E. coli O157:H7 among event attendees. These behaviors are well known to increase the risk for human infection, especially for children who are exposed to animals in public settings. Recommendations for reducing the risk of illness in these settings include evaluate and update plans for cleaning and disinfection before, during and after events; evaluate and update measures to restrict access to areas more likely to be contaminated with manure or fecal material; ensure access to hand washing facilities with soap, running water, and disposable towels, as well as the use of signs and other reminders to attendees to wash hands when leaving animal areas. 

 Marler Clark represented 9 people affected by the outbreak, achieving settlements covering medical expenses, wage loss, pain and suffering, and loss of enjoyment of life.