The new strand of the virus, which has been code named Melissa-X, was detected by antivirus firms overnight. However, unlike its predecessor Melissa, which infected thousands of PCs the world over in 1999, this new variant has only led to a few reported incidents.
Although it initially has been targeted at Mac users - as Office 2001 is only available on the Mac platform - the virus can also infect Microsoft Word users running Windows, according to a notice on the Web site of antivirus company Sophos.
The new variant is similar to Melissa. The virus sends a message to the first 50 addresses in all of the address books accessible by Outlook. This message has the subject line: "Important Message From
Despite its threat, Richard Baldry, Sophos managing director, described the new strand as not particularly virulent, especially when compared to some of the other viruses - such as the Love Bug - which have appeared in the past. Baldry was confident Melissa-X won't spread like the original. "The computer-using public is today far more aware of how to treat unexpected attachments," he said.