Test results turned out negative for a suspected bacteria at Deer Creek State Park beach.

But health officials still don’t know what caused more than a dozen people to get sick after visiting the beach earlier this summer.

More than 15 people reported suspected cases of shigellosis, an infectious disease that causes diarrhea, fever, nausea and vomiting. There were six confirmed cases.

All individuals reporting symptoms had swam at the beach between June 15 and July 17.

The Pickaway Health Department received the results testing for the bacteria on Thursday, according to Emily Deshaief, registered sanitarium. All three tests were negative. Samples were taken last week.

Signs posted last week by the health department warning swimmers of an infectious disease have been removed from the beach.

However, health department officials are still urging caution.

“The precautions stay the same. We still don’t know what caused it,” said Deshaief.

Deer Creek State Park posted on its Facebook page Friday that the beach has received “a clean bill of health.”

“I’m not sure we’re willing to say that because samples were taken after the dates of people being at the beach,” she said. “We still don’t know what it was, but because of the tests we feel comfortable taking the advisory down.”

Tips include hand washing, avoiding getting water into your mouth and avoiding getting into the water if you have diarrhea. Water can also be contaminated by diapers.

“Any time you’re in any open body of water, you can get sick,” she said. “It’s not a treated pool.”

She urged residents to “swim carefully.”

It’s the same bacteria linked last month to Long’s Retreat Family Resort in Latham, Ohio.

The Pike County Health District identified approximately 140 people with symptoms. All had recently visited the resort. Twenty out of 25 stool samples from sick individuals tested positive for shigella.

Andrea Chaffin can be reached at 740-852-1616, ext. 1619 or via Twitter @AndeeWrites.