Outbreak of Escherichia coli O157:H7 Infections Associated with Dairy Education Event Attendance - Whatcom County, Washington, 2015.

On April 27, 2015, the Whatcom County Health Department (WCHD) in Bellingham, Washington, was notified by a local laboratory regarding three children with presumptive Escherichia coli O157 infection. WCHD interviewed the parents, who indicated that all three children had attended a dairy education event held in a barn April 20­24, 2015, during a school field trip. WCHD, the Washington State Department of Health, and CDC investigated to determine the magnitude of the outbreak, identify risk factors and potential environmental sources of infection, and develop recommendations. A total of 60 cases (25 confirmed and 35 probable) were identified, and 11 patients were hospitalized.

Risk factors for campylobacteriosis in two washington state counties with high numbers of dairy farms.

Campylobacteriosis is a frequently reported, food-borne, human bacterial disease that can be associated with ruminant reservoirs, although public health messages primarily focus on poultry. In Washington State, the two counties with the highest concentrations of dairy cattle also report the highest incidences of campylobacteriosis. Conditional logistic regression analysis of case-control data from both counties found living or working on a dairy farm (odds ratio [OR], 6.7 [95% confidence interval [CI], 1.7 to 26.4]) and Hispanic ethnicity (OR, 6.4 [95% CI, 3.1 to 13.1]) to have the strongest significant positive associations with campylobacteriosis. When the analysis was restricted to residents of one county, Hispanic ethnicity (OR, 9.3 [95% CI, 3.9 to 22.2]), contact with cattle (OR, 5.0 [95% CI, 1.3 to 19.5]), and pet ownership (OR, 2.6 [95% CI, 1.1 to 6.3]) were found to be independent risk factors for disease. Campylobacter jejuni isolates from human (n = 65), bovine (n = 28), and retail poultry (n = 27) sources from the same counties were compared using multilocus sequence typing. These results indicated that sequence types commonly found in human isolates were also commonly found in bovine isolates. These findings suggest that, in areas with high concentrations of dairy cattle, exposure to dairy cattle may be more important than food-borne exposure to poultry products as a risk for campylobacteriosis.