Doctors fear that stars such as Madonna, Demi Moore, Bruce Willis and Gwyneth Paltrow may have hepatitis after it emerged that a barman working at Ashton Kutcher's recent birthday party had the liver disease.

The Punk’d star celebrated his 30th birthday at New York’s Socialista club on 7th February with a host of celebrity friends.

The Hepatitis A-infected barman had been employed to help out on that night and now doctors are worried some of Ashton’s guests may have contracted it through him.

The New York City Health Department have urged the stars to get a hepatitis shot as a precaution in case they contract the disease.

Fortunately, if infected the majority of people recover within a few weeks, so there should be no need to worry about your favourite stars!

Hepatitis A is usually spread because of poor personal hygiene. The most common causes of infection are contaminated food or water and person-to-person contact.