The Whatcom County Health Department in the state of Washington reported an outbreak of Shiga toxin-producing E. coli (STEC) affecting 32 children and adults on April 30.  Four cases have been hospitalized, one of which is a child who has reportedly developed haemolytic uremic syndrome (HUS).


Haemolytic uremic syndrome is the most severe manifestation of STEC which may lead to life-threatening kidney failure.  The symptoms of infection with STEC, also referred to as enterohemorrhagic E. coli (EHEC), include diarrhea (that can range from mild, non-bloody to virtually all blood), stomach cramps and vomiting. Seventeen of the cases have been confirmed by laboratory tests.

The health department believes the general source of the outbreak was an event held at the Northwest Washington Fair and Event Center in Lynden, Washington during three days, April 21-23.  It is estimated that over 1,300 children and their adult chaperones attended the 22nd annual Milk Makers Fest, which featured a petting zoo of small farm animals.

Transmission of STEC is by the oral-fecal route, mainly through ingestion of fecally contaminated food or contact with ruminant animals.  The specific point source of this outbreak has not yet been identified.  Sponsors of the event had required hand disinfection at soap and water and hand sanitizer stations at the entrances and exits of the petting zoo.

The mother of one of the hospitalized cases stated that her son told her that hand sanitizer was used to clean his hands, according to KOMO News. Chocolate milk was provided to the children attending the event, but health officials believe it was not a likely source since it had been pasteurized. Direct person-to-person transmission is common with STEC, in particular between family members, but it is unknown at this time how many secondary cases there may be related to this outbreak.

Steven Smith, M.Sc. is an Infectious diseases epidemiologist