There's now one confirmed case of norovirus associated with an investigation of restaurant chain Buffalo Wild Wings (NASDAQ: BWLD), Kansas health officials said Friday.

The Johnson County Department of Health and Environment obtained lab test results confirming a positive case of the foodborne illness, it said in a release, with additional test results pending.

The Buffalo Wild Wings investigation is one of multiple outbreaks in the area, the state health department said.

The Kansas Department of Health and Environment said earlier this week that it received more than 600 reports of illness related to various locations in Overland Park, Kansas, during the end of January. Just 10 of those cases are associated with Buffalo Wild Wings, while most are associated with a different restaurant nearby.

Buffalo Wild Wings spokeswoman Heather Leiferman told CNBC that despite one positive norovirus test, there's no confirmation that Overland Park's Buffalo Wild Wings is the source.

"We understand that the Johnson County health department is investigating multiple potential sources of the virus, which has been widespread in the community for several weeks," Leiferman said. "We are monitoring the situation and will continue to work closely with health department until their investigation is complete."

Buffalo Wild Wings shares closed down more than 8 percent Friday after dropping as much as 12.7 percent earlier in the day. News of the virus came ahead of the busy Super Bowl Sunday, and after the chain said it experienced lower same-store sales during the holiday season.

After an educational visit from the health department, the restaurant location hired a private firm that cleaned the entire facility with a disinfectant, which kills norovirus and is safe for food establishments, the state health department said Monday. Leiferman called the deep cleaning an action taken "out of an abundance of caution."

Symptoms of norovirus include diarrhea, vomiting, nausea and stomach pain, and usually develop 12 to 48 hours after being exposed, the Kansas Department of Health and Environment said in a release.

"These types of illness are common this time of year," said Lougene Marsh, a Johnson County health official, in a statement. "The best thing you can do is wash your hands properly and stay home when you are sick to prevent the spread of these types of illness."

CORRECTION: The health department overseeing a norovirus outbreak in Overland Park, Kansas, is surveying customers of a restaurant near the local Buffalo Wild Wings. The scope of the survey was misstated in an earlier version of this article.

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