An outbreak of syphilis threatens to shut down the porn industry in America.More than 1,000 performers in the Los Angeles area are being tested and administered preventative antibiotics.Officials are now warning the STI spate could jsut be "the tip of the iceberg".The dramatic move comes after five actors were found to have the disease, including a “major male porn star” who was rumoured to have been infected but continued to film scenes.The man could have potentially had unprotected sex with hundreds of women on camera, according to numerous adult film industry blogs.The Public Health Department in Los Angeles confirmed the small cluster of positive syphilis tests.“Whenever there is a cluster like that it may be the tip of the iceberg,” said Peter Kerndt, director of the LA’s Sexually Transmitted Disease program.“It is a concern. It is a serious health risk to workers in this industry.”There are now calls for a temporary moratorium on adult film production until all performers get tested from industry bodies, including porn star resource Adult Production Health & Safety Services.The outbreak is likely to bolster an upcoming ballot aiming to force all porn performers to wear condoms during shoots.Syphilis is a treatable bacterial infection spread by bodily fluids and contact with infected skin.It causes skin lesions and rashes but if left untreated the infection can permanently damage internal organs and brain function.