RICHLAND CENTER, Wis. -- University of Wisconsin Hospital officials said a 6-year-old boy with a life-threatening kidney disease might have been infected while playing in contaminated floodwater.

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Dr. Ellen Wald, a UW hospital infectious disease specialist, said the child has been on dialysis and in intensive care since Sunday. She said he will probably stay in the hospital for at least a week.

It's the first known health problem possibly linked to widespread flooding in Wisconsin earlier this month.

Authorities and health officials are again warning residents that sewage plants were overwhelmed during the storms and water might be contaminated with bacteria. They have also said that water can be contaminated by animal waste and that the E. coli bacteria grows quickly after flooding due to the standing water, WISC-TV reported.

"At this time when there's been flooding of creeks, its probably not a good playground for kids, just because I think children have their hands in the water then they have their hands in their mouth and I think that's the way they could ingest it," said Wald.

Wald said the boy started vomiting three days after playing in a flooded creek near his home in Richland Center. He was first taken to the hospital in Richland Center before being transferred to Madison.

She said a test for E. coli 0157 was negative, but doctors think he has another, hard-to-detect strain of the bacteria.

Wald is encouraging anyone coming in contact with the floodwaters to wash both their hands and clothes with soap and water or bleach to kill the bacteria.

Doctors said the boy's siblings also ended up with E. coli, but the less serious forms of it. They have since been treated and released.

State officials said more than 160 communities have discharged untreated sewage into streams and lakes because flooding shut down their treatment systems. The releases totaled more than 800 million gallons of sewage.