A man accused of knowingly exposing another man to the virus that causes AIDS also may have exposed up to 80 others, Spokane health officials say.

Zuriel Roush, 22, on Wednesday pleaded not guilty in Spokane County Superior Court to charges of first-degree assault.

Roush, who is HIV-positive, is accused of lying about his HIV status to a married man he had sex with in April. The man later learned Roush had the virus and called police, court documents say.

Roush was being held on $100,000 bond, with trial set for July 20.

Detectives have talked with about 10 people who had unprotected sex with Roush, The Spokesman-Review reported Friday. But Spokane Regional Health District officials said up to 80 of his sex partners may have been exposed to the virus.

"Since I've been here we've not had an investigation of this magnitude," said district spokeswoman Julie Graham, who's been with the district for at least five years.

According to court documents, Roush signed health district paperwork last year warning him it was a crime to expose people to the virus without telling them. But Roush's friends told police that he routinely meets anonymous men on the Internet and that he often visited a local park to have sex.

Court documents state that Roush told a friend he's had multiple sex partners since last year.

The health district has a process for discouraging risky sexual behavior, which can include issuing a cease-and-desist order, which if violated, can land the client in the court system.

"On a rare occasion that we find out that someone has intentionally put others at risk, we would take the actions first to keep that from happening," Graham said. "This is our first time where we have had our records subpoenaed by police as a first step."

Roush was diagnosed HIV-positive last fall.

Authorities are concerned that the men who had sex with Roush may not recognize him or be willing to come forward. They urge anyone who may have been at risk to get tested.

"The problem was that a lot of it was anonymous sex or on first-name basis only," said Officer Jennifer DeRuwe, a Spokane police spokeswoman.

Roush declined to be interviewed by The Spokesman-Review. At his arraignment, his father pleaded unsuccessfully with the court to reduce the bond and let his son be released to the family.

"Knowing my son right now, he pretty much knows that he's made a big mistake and that will not happen again," Eldon Roush said.