Posted Friday, July 13, 2012 --- 7:40 a.m.

BLACK RIVER FALLS, Wis. (AP) -- Lake Wazee beach in Jackson County will remain closed through the weekend while health officials determine what made dozens of swimmers sick.

The county's health officer, Christine Hovell, says the likely cause of contamination found in the water at the popular beach is norovirus. It's a contagious infection that causes flu-like symptoms.

Samples from some of the sick swimmers are being tested at the State Lab of Hygiene. Health officials will test the beach water again on Monday. Hovell tells WKBT-TV (http://bit.ly/N9uXxg ) the hot temperatures and sunlight will help destroy contaminants in the water.

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Information from: WKBT-TV, http://www.wkbt.com

Copyright 2012. The Associated Press.