It’s a new kind of virus for Sun Microsystems Inc.

At the company’s JavaOne conference this week in San Francisco, 70 people came down with what officials believe is norovirus, a type of medical virus easily spread by touching dirty surfaces.

The city’s Department of Public Health started receiving reports on Wednesday. On Thursday and Friday, the department warned people who felt they had been infected to stay home.

Shawn Dainas, a spokesman for Santa Clara-based Sun Microsystems, which makes servers and software and is accustomed to protecting against viruses of the digital variety, said the company also alerted attendees about the illness by e-mail.

David Perry, spokesman for the Moscone Center, said 67 of people infected were staff working at the weeklong conference and 3 were attendees. He said the facility had been fully cleaned and disinfected by Friday afternoon, when the conference was winding down on schedule.

Norovirus causes nausea, vomiting and diarrhea and lasts 24 to 48 hours.

No victims were hospitalized, said Jim Soos, the health department’s assistant director of public policy and planning.

Workers disinfected surfaces including food preparation tables, escalator handrails, desks and bathrooms to reduce the risk of the virus spreading further, Soos said. It was unclear where the virus started.

“We’re saying that healthy people should be careful, wash their hands a lot, kind of the standard public health practices,” he said.