03/28/2008 02:46 am ET Updated May 25, 2011

Ashton Kutcher's Birthday Crashed By Hepatitis A

Uh-oh! Ashton Kutcher may have been Punk'd by a trendy New York restaurant. Earlier this month, wife Demi Moore threw her husband a 30th birthday party at Socialista, and it turns out his star-studded guest list may have been exposed to hepatitis:

Today, the New York City Health Department said a bartender at Socialista might have passed hepatitis A to club patrons early this month. The bartender only worked on three nights when he might have been infectious, but one of those nights -- Feb. 7 -- was the night of Kutcher's party.

Hepatitis is a swelling of the liver. Hepatitis A is spread "primarily through food or water contaminated by stool from an infected person," according to NIH.

Hep A is less serious than other forms of the disease, and usually gets better on its own in a few weeks. Still, health officials are recommending vaccination for anyone who may have been exposed. An estimated 700-800 people may have visited Socialista the nights the infected bartender worked, but no additional cases of illness have been identified, the Health Department said. (Note to frugal celebs: The Health Department is offering free shots at P.S. 41 in Greenwich Village this weekend.)

The day manager who answered the phone at Socialista this afternoon told the Health Blog that the bartender apparently got hepatitis on a recent vacation to Honduras, and just found out he had the bug. "We're doing everything we possibly can to make sure that no one comes in contact with this virus," the manager said.

Celebrities in attendance included, but are not limited to, Bruce Willis, Salma Hayek, Madonna, Lucy Liu, Kate Hudson, Molly Sims, Liv Tyler, Gwyneth Paltrow, Eric Dane, his wife Rebecca Gayheart and designer Roberto Cavalli