Two other performers- Cameron Bay and Rod Daily- have come forward and announced that they tested positive, but the third infectee has not revealed their name.
Radar Online reports that 'a dozen female performers have been quarantined as a result of exposure' as a result of the third case.
The latest case is renewing concerns over the health of porn stars as a result of the growing number who have confirmed sexually transmitted diseases.
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Diagnosed: Rod Daily, 32, announced via Twitter that he was recently diagnosed with HIV
After Cameron Bay came out as being infected, a brief moratorium was issued that stopped all productions of pornographic films, but that was lifted just days later.
When Rod Daily announced via Twitter that he had tested positive for HIV less than two weeks after Bay made her announcement, he advocated for further precautions to be taken.
'Drumroll please!! I'm 32 years old and I'm HIV positive. Acute HIV, which means I recently was infected. For that I am blessed,' Daily wrote on Twitter on Tuesday.
'I'm blessed for the fact that I caught it so early that I can blast that s*** with meds.
'With the tests I have done the doctors have figured out that I was infected within the last month...My antibodies just showed up on a test this week which is scary because they didn't a week ago,' he said in two other tweets.
A trade group representing producers of pornographic movies in Los Angeles called on any of Daily's sexual partners to be tested for the virus.
However, the group, the Free Speech Coalition, stepped short of calling for a moratorium on adult film productions.
Porn actor diagnosed with HIV talks safe sex in 2012 interview
Positive attitude: Daily, who has been in the adult film industry for eight years, said that hopefully this will encourage porn stars to wear condoms
Out in the open: Daily announced his positive diagnosis on Twitter Tuesday
The group said it could not yet confirm whether Daily truly had contracted the human immunodeficiency virus, or HIV, but it warned his partners to be tested.
The Free Speech Coalition were the ones to confirm on August 22 that the actress who goes by the name of Cameron Bay was also infected with HIV.
Daily has been linked romantically to Bay on the adult film industry website XBiz.com.
California Assemblyman Isadore Hall, who has been trying for months to get a bill passed in the state Assembly mandating the use of condoms in sex scenes, said Daily's reported infection shows the need for such a regulation.
'This is the second individual within a week and a half to contract HIV in the industry,' said Hall, a Democrat.
'There will probably be more.'
The multibillion-dollar adult film industry is centered in the San Fernando Valley area of Los Angeles.
Distraught: Cameron Bay's agent says his client, whose recent HIV diagnosis has brought the porn industry to a standstill, is 'distraught' over the news
Risk: Xander Corvus, left, who played Weiner in the movie with Sydney Leathers, had unprotected sex with Cameron Bay, right, a few weeks ago - who has just been told she has HIV
Debut: Sydney Leathers porn movie was released yesterday where she stars alongside Xander Corvus
The industry has vigorously opposed efforts to require condom use on set, protesting against a 2012 voter-approved measure requiring condoms to be used in Los Angeles County and successfully arguing against an earlier effort for such regulation at the state level that would be specifically geared to film productions.
The Free Speech Coalition said in an email to Reuters that Daily acted in gay and transsexual sex movies in which condoms were used.
After Bay tested positive, production was shut down for about a week.
Medical signs: Daily said that the test suggests he contracted HIV in the past month
But as of early evening on Tuesday, no order to cease shooting sex scenes had been issued.
In a series of Twitter postings, Daily cited this brief moratorium as an example of how the industry is unwilling to change- to the detriment of it's actors.
'That does not change anything though. A week later people are back at it shooting without condoms.
'I have also learned that people can be so well medicated that they test negative. Scary, the test everyone relies on.
'Magic Johnson has HIV, and can infect other people but his test comes up negative. Is that so impossible for anyone else to do the same? NO.
'Just sayin be careful because that test ain't shit without a condom strapped up with it.'
Daily appears to be taking a positive approach to the news, staying optimistic by saying: 'Had to pinch myself a few times no doubt. But the sun still shines on my face and its warm. Can't take my heart ever. I love life, blessed.'
'I felt bad for the guy who had to read me my first test result. His face turned to stone, I wanted to give him a hug and say it will be ok.'
Bay's scare resonated outside of the porn industry, as it was revealed that she had recently had sex with the male performer who later appeared in a video starring Sydney Leathers, disgraced congressman Anthony Weiner's sexting partner.
Daily Mail