The fountain at Plaza de Cesar Chavez Park in downtown San Jose, the interactive fountain that has long been a magnet for frolicking children, has now been closed indefinitely.

County health officials believe the popular water feature is the common denominator for seven confirmed cases of cryptosporidiosis — a diarrheal infection — and possibly 15 recent cases of salmonella infection, which also causes diarrhea, nausea and cramps.

Seven children with cryptosporidiosis linked to the fountain are between 1 and 13 years of age. One was hospitalized, but has since been released and has recovered. Health officials are also reviewing 15 cases of salmonella infection in children between the ages of 1 and 15 who fell ill.

“Right now, we’re not 100 percent sure how this occurred,’” said Mike Will, the city’s acting parks manager. The water is basically tap water to begin with, and is chlorinated, Fenstersheib said. But because it is recycled — and chlorine is ineffective at killing Cryptosporidium and salmonella — illnesses can occur.

When — or whether — the fountain will reopen is uncertain.