TALLAHASSEE, Fla. (AP) – State health officials said Friday at least 15 people, including 11 children, who recently visited central Florida festivals have since tested positive for a dangerous strain of E. coli, or a potentially fatal kidney disease caused by the bacterium.

While local health officials have said the cases appeared to be linked to petting zoos at the festivals, state Health Secretary John Agwunobi cautioned the link is not definitive.

Agwunobi said the bacterium also could have been contracted from consuming tainted food or drink, or from some other activity – riding ponies or other animals, petting livestock, milking cows of other situations where people might be close to animals or animal waste.

The 15 people all visited either the Central Florida Fair in Orlando or the Florida Strawberry Festival in Plant City, which were held in early March.

All have had diarrhea and have either tested positive for the particular E. coli strain or developed the kidney disease known as hemolytic uremic syndrome, or HUS, which is caused by toxins from the E. coli infection.

Various Orlando-area hospitals reported at least 13 people hospitalized with HUS or infections of E. coli Friday, at least three of them in critical condition.

It wasn’t clear whether the other two people being monitored by state health officials were hospitalized.

Agwunobi said if someone develops HUS, it might be two or three weeks after having diarrhea; symptoms would likely include lethargy, puffiness and vomiting.