Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2004
Publication Date: November 1, 2004
Citation: Reynolds, K.M., Keen, J.E., Durso, L.M., Bauer, N. 2004. Investigation of an STEC O157 outbreak at a 2003 Texas county fair [abstract]. Research Workers in Animal Diseases Conference. p. 120.
Since 1999, at least eight outbreaks of shiga-toxigenic Escherichia coli (STEC) O157 have been linked with visits to US county fairs. Cumulatively, these incidents have sickened more than a thousand persons (including >300 culture-confirmed cases) and caused at least 38 cases of hemolytic uremic syndrome (HUS) and two deaths. In fall 2003, STEC O157 infected at least 24 persons among the 180,000 visitors and exhibitors at the Fort Bend County Fair in Rosenberg, TX, which ran from 9/26/03 to 10/4/03. Seven culture-confirmed persons, four HUS cases and one thrombotic thrombocytopenic purpura (TTP) case were outbreak-associated. A fairground sewage overflow, contaminated food or water, and animal contact were initial suspect sources of human infection. All human STEC O157 isolates shared the same pulsed-field gel electrophoresis (PFGE) pattern. All patients were either fair exhibitors or visitors to animal exhibits. No apparent pattern of food or beverage consumption linked the ill persons. Six weeks after the fair, environmental samples were collected at sewage overflow and animal husbandry areas of the fairgrounds and at the adjoining rodeo arena. Ten of 62 environmental sites sampled were STEC O157 culture-positive: five animal sites and five rodeo sites. The 28 isolates derived from the ten positive sites had eight different PFGE patterns. All ten isolates from four animal husbandry sites matched patient PFGE patterns. These findings suggest that while both the rodeo and animal husbandry areas of the fair were heavily STEC O157 contaminated, the outbreak strain was only found in animal exhibit areas, pointing to direct or indirect livestock contact as the most likely source of human infection.