County public health officials backtracked on the number of previously unpublicized HIV cases in adult film performers Tuesday, saying they don't know if those who tested positive were actively working in the industry at the time.

Last week county officials told The Los Angeles Times that there were at least 16 cases of HIV in adult film performers reported to them since 2004. The disclosure came after news that a female porn performer recently tested HIV positive.

On Tuesday, the department told the Times it does not know if any of the people who tested positive were actively performing in the adult film industry.

Officials also corrected the number of new cases adjusting the figure upward from 16 to 18.

The Adult Industry Medical Foundation, the San Fernando Valley clinic that serves the porn industry, said none of the people were actively performing when they were tested.

Clinic co-founder Sharon Mitchell said each case involved either a non-performer or an aspiring actor or actress who tested positive, then dropped out of the business.

County public health officials said they mislabeled all reports from the clinic as adult performers, when they had no information about their occupations. The clinic was created primarily to serve the porn industry, but also serves other clients.

"Here's the bottom line: we're an HIV testing center," Mitchell, said. "We don't just test the adult entertainment industry. We have a lot of people who come who want testing from the general public."

The female actress who tested positive for HIV at their clinic earlier this month remains the only case detected in a working performer since 2004, Mitchell said.

In 2004, panic spread through the industry and briefly shut down production at several studios, after a male porn star and three actresses he worked with tested positive.

Public Health Director Dr. Jonathan Fielding said the county does not have enough information to explore these cases further.

"The system we have and the laws we have do not facilitate the kind of contact tracing and verification that we'd like to see. AIDS has been treated separately from other STDs," Fielding said.

In HIV cases, the medical clinic or doctor who conducts the test is responsible for notifying partners, Fielding said. For other sexually transmitted diseases, state laws allow the county to make partner notification.

"I'm sure that AIM provides a useful service to the degree that they prevent performers from performing when they have sexually transmitted diseases or HIV," Fielding said.

He said AIM's efforts are "better than nothing," but not enough to prevent a life-threatening occupational hazard.