It's perhaps a good sign for public health when I don't tend to come home from a local fair and write a rant about the sorry state of the petting zoo. Around here, things seem to have improved at most events over the past few years, probably largely because of the efforts of local public health personnel. However, some establishments still fall through the cracks and regardless, even with optimal management, there's always some degree of risk with contact between animals and the public.
Welsh authorities are investigating a small (so far... and hopefully to remain that way) outbreak of E. coli O157 that has been tentatively linked to Cantref Adventure Farm. The two children became ill after visiting the farm. Two family members of one child have also tested positive for the bacterium, and it's believed that one of them was infected via contact with child (as opposed to direct contact with animals at the farm). Since both kids visited the farm in the days before they got sick, and since petting zoos are a prime source of E. coli outbreaks, it's logical to assume the farm was the source. Even though this has not yet proven, the reason to make this early assumption before a link can be definitively established is to get the word out to others that may have visited the petting zoo, in case there are more cases of illness. Authorities are telling people who visited the farm since the beginning of August to contact their physician. It's not clear whether they want to test everyone (by collecting a stool sample) or just have them checked out to make sure they are okay.
Meanwhile, the investigation at the farm is ongoing. Presumably, stool samples from animals on the premises and environmental samples have been collected to see if the same strain of E. coli is present. All direct contact between the public and animals on the farm has been stopped, and the site is being thoroughly cleaned. That's a pretty standard response overall, and hopefully if the petting zoo was the source, transmission has ceased.
Petting zoos can be fun and educational and we don't want to over-react and assume they are all inherently dangerous. There's always some degree of risk of infectious disease exposure, and the key is making sure petting zoos are run optimally to reduce, as much as possible, the risk to the public. The public also has to play a role, by following rules, supervising children and (probably most importantly) actually using hand sanitizers and handwashing stations that are provided.