Syphilis is a dangerous infection transmitted during sexual contact with a person who has the disease. It can have very serious complications if not treated, including visual problems and blindness, hearing loss, stroke, other nervous system problems, even death. Syphilis infection also increases a person’s risk for getting HIV or giving it to others.

Syphilis has increased 67 percent from 2011-2015, in men, women and some newborns. Syphilis among newborns has increased along with the national increases of syphilis in women of childbearing age. It can cause miscarriage, stillbirth, early infant death or severe illness in babies who survive.

Primary and secondary (P&S) syphilis – the most infectious stages of the disease – have increased almost 20 percent between 2014 and 2015. There’s a similar rate of increase in the first six months of 2016. Rates have increased for men and women, but men account for more than 90 percent of all P&S cases. Gay, bisexual and other men who have sex with men (MSM) account for 82 percent of male cases where the gender of the partner is known.

Syphilis symptoms

Without treatment, syphilis progresses in four stages, each with its own symptoms. Throughout each stage, a person can pass on syphilis to others. Many of these early symptoms are so common that the infected person may not notice them or don’t think they need to be tested.

Within about three weeks of exposure (up to three months), a painless sore develops at the site where the bacteria entered the body. This is often the genital or anal area. A person is highly contagious during this primary stage of three to six weeks. The sore heals without treatment.

During the second stage (within 2-12 weeks of exposure), a rash of reddish brown, solid, flat or raised sores develops over the body. It is most common on the palms of the hands and soles of the feet. Open sores can also occur on mucous membranes such as the genital area or inside the mouth. Secondary-stage sores also heal without treatment.

However, without treatment the disease spreads throughout the body during the third stage. Symptoms may include fever, sore throat, weakness, weight loss, hair loss, headaches, paralysis and irregular pupils.

About a year after infection, the person enters the final, latent stage. This can last one to 20 years. Generally, there are no symptoms during the latent stage but some people can relapse and symptoms occur again. For most, but not all people, syphilis progresses and damages internal organs, causing heart disease, mental disorders, blindness, nervous system problems or large sores inside the body or on the skin.

Many men with syphilis do not have symptoms. That is another reason to be tested frequently if you are sexually active.

All 50 states require that syphilis cases be reported to the state or local public health agency so they can take action to find and treat exposed persons. This prevents others from becoming infected and prevents the devastating complications of untreated syphilis.

Treating it early

There is no simple test for syphilis. It requires two blood tests and this can lead to treatment delays. Tests are hard to interpret and they cannot detect an early infection.

There is no vaccine to prevent syphilis. However, it can be cured and treatment is simple. The antibiotic penicillin has been used to treat syphilis since 1943 and remains the best drug to treat it. Prompt treatment is essential to cure the infection, keep it from spreading and prevent complications. That’s why it’s important for you and your sexual partner (s) to be tested regularly, or any time the above symptoms appear.

If you receive syphilis treatment, do not have any sexual contact until the syphilis sores are completely healed. If you have syphilis you must notify all your sex partners so they can be tested and receive treatment.

Preventing syphilis

You can lower your chances of getting syphilis in four ways:

  • Use a latex condom every time you have sex. However, if your partner has a syphilis sore outside of the area covered by a condom, you can easily get the infection. Always be cautious even when using a condom.
  • Stay in a long-term, mutually monogamous relationship with a partner who has been tested and has negative STD test results.
  • Avoid all types of sexual contact, including oral sex.
  • Get tested every three to six months if you have sex with more than one partner, don’t use condoms or engage in risky sexual behaviors.

Who should be tested?

  • Pregnant women should be tested for syphilis during the first pre-natal visit. The baby can get syphilis at any stage of pregnancy. About 40 percent of babies born to women with untreated syphilis are born dead or die from the infection as a newborn. Untreated babies who survive can develop problems later on, including delays in development, and bone and joint deformities.
  • Men who have sex with men (MSM) should be tested at least every year, according to CDC recommendations. MSM account for about two-thirds of syphilis cases.
  • Anyone who is sexually active but does not use condoms or does not use them correctly should be tested at least every year.
  • Anyone who has multiple sex partners, has a sex partner or lives with someone who has syphilis or HIV should be tested at least annually. Syphilis causes open sores that allow the HIV infection to enter the body easily.
  • Anyone with sores, bumps, rashes, blisters or warts on or around your genital or anal area or on any area where they could have been caused by a STI should be tested immediately.
  • All sex partners of a person with untreated syphilis needs to be tested and treated. Do not have sex or other sexual contact until you have been treated.

In most areas, public health clinics or county health departments can diagnose and provide no- or low-cost treatment of early syphilis or other STIs.

NIAID researchers are working on ways to develop a vaccine for syphilis, and to develop a simpler, more accurate test that does not require a blood test. Current tests are hard to interpret and they cannot detect an early infection.