A pornography trade group has called for a nationwide filming moratorium while performers are tested for syphilis and Los Angeles County public health officials investigate a possible outbreak of the sexually transmitted disease.

One performer has tested positive, and the performer's sexual partners are being notified, according to Joanne Cachapero, a spokeswoman for the Free Speech Coalition.

The voluntary, temporary moratorium on production is expected to shutter a multi-billion dollar industry "until the risk to performers in the industry has been properly assessed and all performers have been tested," the trade association said in a statement.

On Friday, the Los Angeles County Public Health Department announced an investigation into at least five possible cases of syphilis that were reported last week.

Cachapero said the group is calling on all performers, more than 1,000, to be tested. Because the illness can be difficult to detect, the trade group's medical experts have ordered preventative shots of antibiotics for performers. After performers get the shots, they can go back to work within 10 days, Cachapero said.

According to the Centers for Disease Control and Prevention, syphilis is transmitted through direct contact with syphilis sores, which mainly occur on the external genitals, vagina, anus or inside the rectum. The disease can be transmitted through a variety of sex acts.

A single shot of penicillin can cure a person who has had syphilis for less than a year, according to the CDC. Additional doses are necessary for people who have had the STD for a longer period.

County public health spokeswoman Sarah Kissell acknowledged the investigation Monday but declined an interview seeking details of its scope or an update of its findings.

Latest moratorium

The porn industry has held self-imposed moratoriums following news of diseased performers before.

In 2011, major porn producers stopped filming for nearly a week after an adult film performer tested positive for HIV, which causes AIDS. The Free Speech Coalition said the case was later determined to have been a false report.

In late 2010, porn actor Derrick Burts was diagnosed as HIV-positive, and his case was confirmed, briefly halting production.

In 2004, at least five performers tested positive for HIV, prompting another brief self-imposed moratorium.

The AIDS Healthcare Foundation, an advocacy group that has called for the use of condoms in all pornography, said Monday that the industry is incapable of policing itself and protecting its performers.

The group is backing a November ballot measure that will allow Los Angeles county voters to mandate the use of condoms during pornography shoots.

The Free Speech Coalition opposes the measure, saying the industry is a tight-knit community that has been proactive in testing and protecting the welfare of performers.