Nearly three months after E. coli O157:H7 sickened 25 people who attended the North Carolina State Fair, investigators know little more about what caused the outbreak, other than   it originated in a livestock building on the fairgrounds.    

Field notes published Thursday, from the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report, confirmed that the only space visited by all outbreak victims was a permanent structure where sheep, goats and pigs were kept during livestock competitions.

Eight of the fairgoers became so sick they required hospitalization. Four developed hemolytic uremic syndrome (HUS), a life-threatening complication of E. coli infection.  

And while the exact source of the E. coli O157:H7 exposure remains unclear, the investigators conclude that it likely was contact with the animals.

“Fair attendees were not intended to have physical contact with animals in the building,” the CDC noted, but 25 percent of the case patients said they did.

The conclusion echoes the findings of an investigation into a 2004 outbreak, also at the North Carolina State Fair. That year E. coli bacteria traced to the fair’s petting zoo sickened 187 people, 15 of whom were hospitalized with HUS.  

After that outbreak, the North Carolina Legislature adopted Aedin’s Law – named after a boy who developed a serious case of HUS. The law stipulates, among other things, that animal exhibitors must carry a public permit if visitors come into contact with animals.

However, because the animals housed in the Kelley Livestock Building during the 2011 State Fair were not intended to be touched by fairgoers, the facility was not subject to the law.

The building did have certain sanitation measures in effect, in accordance with a national set of recommendations for public animal exhibits that has been in place since May 2011. For instance,  the facility had posted educational signs about animal hygiene and provided hand-washing facilities for visitors.

The CDC announced that the next step in the 2011 North Carolina State Fair investigation will be evaluating the sanitation precautions that were in place when the outbreak occurred, and identifying further ways to prevent the spread of disease at animal exhibitions. A multiagency task force is being formed in North Carolina for this purpose.