The trade association that monitors the pornography industry in the U.S. has called for a nation-wide moratorium on filming as it deals with a possible syphilis outbreak among performers.

The Free Speech Coalition is providing syphilis testing for all actors in the industry, as well as treatment for those who need it, after a performer reportedly tested positive.

The Los Angeles-based actors' sexual partners are being notified, the FSC said in a statement. As well, Los Angeles County public health officials are investigating whether an outbreak has in fact occurred.

"APHSS' (Adult Production Health and Safety Services) doctors have met and discussed the best avenue to protect the performers and have determined that testing the entire population is the most prudent strategy," said a statement from the FSC.

"A determination will be made by the doctors on the appropriate time to lift the moratorium as more information is revealed."

The voluntary moratorium will likely shut down the multi-billion industry for several weeks, or "until the risk to performers in the industry has been properly assessed and all performers have been tested," said the statement from the FSC.

The FDA statement said a negative test result for syphilis does not necessarily mean the performer receives a clean bill of health. The test may not reveal its presence if a performer was infected with syphilis recently.

As well, a person with an acute infection may test negative and yet still be contagious.

"We cannot rely on these tests alone to determine a performer's availability to work. This test only provides our doctors a baseline from which to base further testing or treatment options," the statement said.

The trade group is also calling for all performers, more than 1,000, to undergo preventative antibiotic shots, after which they could theoretically return to work within 10 days.

Last week, the Los Angeles County Public Health Department announced it was investigating at least five reported cases of possible syphilis.

It's not the first time the adult film industry has voluntarily shut down production over a health scare. In 2011, porn producers stopped filming for close to a week after a performer tested positive for HIV -- though it was later said to be a false report.

And in 2010, a porn actor was diagnosed as HIV-positive, which also halted production. A few years earlier, in 2004, at least five performers tested positive for HIV, leading to another moratorium.

FSC Executive Director Diane Duke said the industry has a history of coming together and putting the health and safety of its performers first, in times of crisis.

"I always appreciate how our industry comes together in a time of need," Duke said in a statement. "Clearly our industry's priority is the health and well-being of our performers. Thank you to all of the producers who have and will contribute and thanks to all of you for honouring the moratorium."

Syphilis can be treated with a single shot of penicillin in patients who have had syphilis for less than a year. Those who have had the sexually transmitted disease for longer than a year require additional doses of penicillin.

It is typically transmitted through direct contact with syphilis sores that generally occur in the genital areas.