A STATEWIDE OUTBREAK OF ESCHERICHIA-COLI O157-H7 INFECTIONS IN WASHINGTON-STATE

In November 1986, a statewide outbreak of Eschertchla coil 0157: H7 infections in Washington State was Identified after a physician in an eastern Washington community hospitalized three patients with hemorrhagic colitis which progressed to thrombotic thrombocytopenic purpura. Epidemiologic investigation identified 37 cases in this community and linked the illnesses to a local restaurant which had served ground beef that was the suspected initial vehicle of transmission. The plasmid profile and toxin production pattern (Shiga-like toxin II alone) of the outbreak strain provided a unique strain marker. E. coil 0157: H7 Infections caused by this strain were simultaneously seen in other parts of the state among nursing home residents and in patients with the hemolytic-uremic syndrome, and an increase in sporadic cases of hemorrhagic colitis was noted at a Seattle health maintenance organization. It is suspected that a contaminated product, probably ground beef distributed statewide, was the common source. Tracing of this meat led to farms where rectal swabs from six (1%) of 539 cattle tested yielded E. coil 0157: H7, although the plasmids and toxin production patterns of these isolates differed from the human outbreak strain. Introduction of a single strain of E. coil 0157: H7 has the potential to cause widespread concurrent outbreaks. Such outbreaks are likely to escape recognition until heightened screening and surveillance for E. coil 0157: H7 is established. © 1990 by The Johns Hopkins University School of Hygiene and Public Health.