A 42-year-old male porn star was sentenced to 30 days in prison, for causing a syphilis outbreak in Los Angeles' adult film industry last year.

Porn star Jesse Spencer, who goes by the screen name Mr Marcus, tested positive for syphilis, a Sexually Transmitted Disease (STD), during a routine test in July last year. He received a penicillin shot immediately and doctors told him he would not be contagious after 10 days.

However, when Spencer returned to work after 11 days, he was still a carrier. Unfortunately, in order to continue working, he decided to hide his syphilis-positive test results.

Spencer has worked for nearly two decades in the adult film industry. The case was heard in the Los Angeles Superior Court, which also sent him to 36 months' probation and 15 days of community labour.

The actor admitted to spreading the disease and the court was told the incident halted all production for 10 days, while all adult film stars in the Los Angeles area were tested. The actors and actresses were also administered preventive antibiotics for STDs.

The tests revealed that at least nine people had contracted syphilis.

"I tried to cover it up...because I said it was like the scarlet letter. It's the word. Syphilis, whoa," Spencer said, adding, "I'm very sorry. I did not think that this would come out like this."

It was revealed that after returning to work, Spencer hid his medical records and substituted them with a copy from his mobile phone, which did not have those details printed. However, his charade was unmasked after a suspicious producer questioned him.

Syphilis is a treatable bacterial infection with a 90-day incubation period. During this period, there are no symptoms and medical tests do not reveal an infection. Syphilis spread either by bodily fluids or contact with infected skin. Sex workers are required to undergo regular blood tests to ensure they are free of Sexually Transmitted Diseases.