SPOKANE, Wash. -- Spokane health officials fear a man with HIV may have had unprotected sex with as many as 80 partners.

A spokeswoman for the regional health district, Julie Graham, told The Spokesman-Review its the biggest investigation in at least five years.

The 22-year-old man, Zuriel Roush, is accused of exposing another man to the virus that causes AIDS. He pleaded not guilty to an assault charge at his arraignment Wednesday in Spokane County Superior Court.

Court documents say Roush signed health district paperwork last year warning him it was a crime to expose people to the virus without warning.

The documents say Roush met men on a Web site and went to People's Park for anonymous sex.

A trial date has been set for July 20.