KNSD-TV reports that Thomas Miguel Guerra entered the plea Monday to violating a state health code against someone with a communicable disease willfully exposing others.
Prosecutors say Guerra claimed to be HIV-negative and urged his boyfriend to have unprotected sex. The other man tested positive for HIV in May of 2013.
During his prosecution, a judge ordered Guerra to stay off dating websites.
Guerra earlier pleaded not guilty. He changed his plea on the day his trial was to start and now faces up to six months in jail and a $1,000 fine.
At least two other men alleged last year that Guerra intentionally infected at least two dozen men in and around the San Diego area.
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