Ashton, Demi & Others Exposed to Hepatitis

Ashton Kutcher's birthday bash has turned into a medical nightmare.

A bartender at the New York club Socialista, where his wife Demi Moore hosted an A-list bash, has tested positive for Hepatitis A, the New York City Department of Health and Mental Hygiene announced today, meaning Ashton and his guests need to get tested too due to exposure.

"In response to a case of Hepatitis A in a bartender at Socialista in Manhattan, the Health Department today notified patrons of the exposure and urged them to get a hepatitis A vaccination as a precautionary measure," the Health Department statement reads. "Hepatitis A is spread by putting something in one's mouth (even though it might look clean) that has been contaminated with traces of fecal matter from an infected person. Any patron who visited the establishment after 8 p.m. on February 7th or 8th, or after 10 p.m. on February 11th (the times the infected person worked after becoming infectious), is considered to be at risk and needs a preventive shot. "

Those in attendance at Ashton's Feb. 7 party included Kate Hudson, Madonna, Bruce Willis, Lucy Liu, Liv Tyler, Roberto Cavalli and past OK! cover boy Eric Dane and his wife Rebecca Gayheart.

Hep A is a viral liver disease. Recovery takes a few weeks with bed rest and alcohol abstinence. Symptoms include jaundice (yellowing of eyes and skin), fatigue, abdominal pain, nausea and diarrhea. Once the symptoms appear, there are no special medicines or antibiotics that can be used to treat it.