Computer viruses and worms will have to share the stage with a new challenger for the attention of attendees at a conference of anti-virus researchers: spam.

Spam - and how to stop it - will be a major topic at this year's Virus Bulletin conference in Chicago. The conference is expected to attract the world's leading anti-virus researchers, law enforcement personnel and corporate security experts.

The interest in spam reflects the increasing prominence of the problem, and the wandering eyes of anti-virus technology companies, which are looking to broaden the number of ailments their products address, according to Matt Ham, a technical consultant at Virus Bulletin. "There's been a lot of movement from just viruses to spam," he said. "People are saying 'We can look for viruses in e-mail, we might as well look for other things, too.'"

Sponsored by the eponymous anti-virus industry magazine, Virus Bulletin is one of a small number of technical conferences that cater to the international community of virus researchers and experts. The gathering caters to those with more than just a passing interest in viruses and malicious code. Presentations at the show have titles such as "Malicious media - ASF scripting" and "Proactive detection of code injection worms."

The show, in its 14th year, is often noted for its "family atmosphere", with researchers from universities and anti-virus companies getting to meet and speak face-to-face after working together remotely to spot and thwart viruses. But the explosion of malicious code in recent years has changed the show's complexion, Ham said.

"In the past, it was possible for one person to know everything there is to know about viruses," he said. "But now the information that is coming out is much broader. One person can't hope to know everything. So instead of vast detail on a tiny part of one virus, people present papers about broader subjects - for example, how to prevent viruses that spread through instant messenger."

Conference organisers sifted through 230 paper submissions this year and selected 30 for presentation, Ham said. Of those, six focus on spam or spam-related topics, compared to just one presentation at the 2003 conference.

The show's changing makeup is not an indication of waning interest in viruses and worms, but does reflect the changing interests of those who attend Virus Bulletin, Ham said. Despite increased press attention to spyware and Trojan horse programs, malware gets short shrift at this year's show, possibly because such programs are already easy to detect, Ham said. "Developers tend to do research on what they consider to be more interesting. Trojans are looked upon as dull," he said.

Virus Bulletin 2004 runs for three days from 29 September.