Ashton Kutcher DMOORE110607_10.jpg Ashton Kutcher's big 30th birthday party earlier this month sure looked like fun - but we're guessing the guests probably wish they'd stayed home instead!

The New York City Health Department issued a press release yesterday warning of a potential outbreak of hepatitis A stemming from a bartender at Socialista who worked on February 7th - the same night and location as Ashton's party!

That means that everyone who attended the party's at risk of contracting the dangerous disease - and considering the party's stacked guest list, that could mean half of Hollywood's got a shot to take!

Guests at the party included Madonna, Kate Hudson, Bruce Willis, Gwyneth Paltrow, Lucy Liu, Liv Tyler, Eric Dane, Rebecca Gayheart, Salma Hayek, Molly Sims, Amy Smart, Ivanka Trump, Parker Posey, Ali Larter, Rachel Zoe, and Roberto Cavalli, among others.

Thankfully, hepatitis A isn't the end of the world - the Health Department estimates that 80-90% of patients vaccinated within 14 days of exposure recover fully, and that fewer than one percent of all hep A cases prove fatal.

Let's hope everyone's already gotten their shots!