The Whatcom County Health Department (WCHD) is investigating an outbreak of shiga toxin-producing E. coli O157 associated with the Milk Makers Fest that was held at the Northwest Fairgrounds in Lynden on 4/21 – 4/23/15.

Over 1,000 primary school children from all of the school districts in Whatcom County attended the event. Most of the cases involve children who attended the event. Several older children involved with the event and some adults and close contacts of cases have also become ill.

WCHD is continuing to interview cases to determine if there was a common food or water source or activity, such as the petting zoo or other contact with livestock. Washington State Department of Health Communicable Disease Epidemiology is assisting with the outbreak investigation.

Cumulative total: 22 cases* (7 cases have been hospitalized), 20 probable cases ** Change since last report of 5/2/15: no new cases, +1 probable cases, no new hospitalizations

*Cases include those with positive labs (preliminary presumptive positive O157 and final confirmed positives), and clinical cases with close contact with a case with positive or presumptive positive labs.

** Probable cases are cases with clinical symptoms and were associated with the event, but lab results are not available or labs were not done.

The state public health lab is testing confirmed E. coli O157 isolates for serogroup (to determine if O157:H7 or another related serogroup). Preliminary positive O157 isolates are regrown and have further testing done at a commercial lab to confirm O157. We expect to get the first results of serogroup testing from the state public health lab this week.