FLINT, Mich. (AP) — The federal Centers for Disease Control and Prevention is continuing an investigation following last year's high numbers in Genesee County of shigellosis, a highly contagious gastrointestinal illness.

The Flint Journal reports a federal study was unable to link the Flint-area outbreak back to a single source, such as tainted food or water.

A final weekly report by the Michigan Disease Surveillance System in 2016 showed there were 136 Shigellosis cases in Genesee County for the year, which the Genesee County Health Department said was up from average of 20 cases in a 365-day period.

The investigation began amid Flint's ongoing crisis with lead-tainted water.

The Genesee County Health Department consulted with the CDC in August after dozens of shigellosis cases. The outbreak also included cases in Saginaw County.

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Information from: The Flint Journal, http://www.mlive.com/flint

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