DALLAS – While the father of a 6-year-old girl told News 8 he is not sure what killed his daughter Monday, investigators are looking into the possibility that cryptosporidium, a waterborne illness, played a part in her death.

The parasite has led to a rash of illnesses across North Texas this summer.

As inviting as water parks, swimming pools and lakes are during triple digit temperatures, health experts worry they could be sickening swimmers because of cryptosporidium.

The number of cases in Dallas, News 8 has learned, could soon skyrocket.

"We had 38 last year," said Zachary Thompson, Director, Dallas County Health Department. "We're already at 47 [this year]. We're looking at over 100 in terms of investigations [right now]. That tells us there are some issues here."

Thursday evening, Thompson said his office is awaiting autopsy results on the 6-year-old girl. She died Monday, two days after being admitted to Medical City for dehydration and vomiting.

Her father told News 8 she was a swimmer but didn't know what could have led to her death.

Tests will take 10 days to confirm whether cryptosporidium played a part in the child’s death. If it is related, it would be the first death from the waterborne illness in recent memory.

Swallowing tainted water can infect people, though it’s uncertain how the girl might have contracted it.

Thompson said the majority of cases in Dallas have been traced back to spray parks that have fountains and jets of water that shoot up from the ground rather than pools of water. They are often unregulated, which is something Thompson said he hopes legislators will change next year.

"Not to say anybody's doing anything wrong," he said. "We're saying that right now, based on the number of cases we're seeing and what we know nationally has happened, it's time to get more stringent guidelines around these water parks."

Experts speculate the economy might be to blame for the outbreak.

More families staying home this summer mean local recreation areas see more visitors.

E-mail jwhitely@wfaa.com