Syphilis is a highly contagious disease that’s mostly spread through sexual activity, including oral and anal sex. The infected person often doesn’t know that they have the disease and passes it on to their sexual partner.
Syphilis is contagious during its primary and secondary stages, and sometimes in the early latent period. The bacteria known as Treponema pallidum transmits it.
You face an increased risk of acquiring syphilis if you:
Engage in unprotected sex
Have sex with multiple partners
Are a man who has sex with men
Are infected with HIV, the virus that causes AIDS
Syphilis infection has three stages:
Early or primary syphilis. People with primary syphilis get one or more sores called chancres. They’re usually small, painless ulcers. They happen on your genitals, on your anus or rectum, or in or around your mouth between 10 and 90 days (3 weeks on average) after you’re exposed to the disease. Even if you don’t treat them, they heal without a scar within 6 weeks. But treatment will keep your disease from moving to the next stage.
Secondary syphilis. This stage begins 6 weeks to 6 months after you’re exposed. It may last 1 to 3 months. People with secondary syphilis usually get a rosy "copper penny" rash on the palms of their hands and soles of their feet. They may also have different rashes on other parts of their body. These may look like rashes caused by other diseases. People may have moist, wart-like lesions in their groin, white patches on the inside of their mouth, swollen lymph glands, fever, hair loss, and weight loss. As with primary syphilis, symptoms of secondary syphilis will get better without treatment.
Syphilis is most infectious in the first two stages.
Syphilis Diagnosis and Tests
Your doctor will need to do a physical exam. They might give you tests including:
Blood tests. A quick test at your doctor’s office or a public health clinic can diagnose syphilis.
Cerebrospinal fluid tests. If your doctor thinks you might have neurosyphilis, they’ll test fluid taken from around your spinal cord.
Darkfield microscopy. Syphilis bacteria are visible through a microscope in fluid taken from a skin sore or lymph node.