Orange County, Florida, health officials are investigating a cluster of illnesses linked to Walt Disney World’s "Wild Africa Trek" experience, a boutique tour in which small groups of people get up-close access to some of the wildlife in Disney’s Animal Kingdom and a catered meal served on the theme park’s manmade savannah.

The Orlando Sentinel reports investigators have documented "several dozens of cases" of illnesses among guests who took the Disney tour in June and July, said Dain Weister, a spokesman for the Orange County Health Department.

The source of the illness remains a mystery.

"It appears to be some kind of stomach bug," Weister said. "It could be foodborne, it could be waterborne, it could be something that’s passed on person-to-person, it could be something that’s picked up by surface."

Disney has taken several precautionary steps, including "deep cleaning" various surfaces that guests touch, distributing more hand sanitizers, and re-emphasizing hand-washing policies to guests and employees.

"We are working closely with the Orange County Health Department to review the situation," Disney spokeswoman Andrea Finger said.

The year-and-a-half-old Wild Africa Trek is one of the most-exclusive experiences at Disney World. Guests pay from $139 to $249 a person — on top of basic park admission — for the three-hour tour, during which they pick their way through wooded overgrowth, peer over a cliff at a pool of hippos, cross a rickety bridge above Nile crocodiles, and dine in a safari-style camp.