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STD Basics


Updated December 12, 2004

How Is Syphilis Diagnosed?

Syphilis is sometimes called "the great imitator" because its early symptoms are similar to those of many other diseases. Sexually active people should consult a doctor or other health care worker about any rash or sore in the genital area. Those who have been treated for another STD, such as gonorrhea, should be tested to be sure they do not also have syphilis.

There are three ways to diagnose syphilis.

  • Recognizing the signs and symptoms
  • Examining blood samples
  • Identifying syphilis bacteria under a microscope
The doctor usually uses all these approaches to diagnose syphilis and decide upon the stage of infection.

Blood tests also provide evidence of infection, although they may give false-negative results (not show signs of an infection despite its presence) for up to 3 months after infection. False-positive tests (showing signs of an infection when it is not present) also can occur. Therefore, two blood tests are usually used. Interpretation of blood tests for syphilis can be difficult, and repeated tests are sometimes necessary to confirm the diagnosis.

How Is Syphilis Treated?

Unfortunately, the early symptoms of syphilis can be very mild, and many people do not seek treatment when they first become infected.

Doctors usually treat patients with syphilis with penicillin, given by injection. They use other antibiotics for patients allergic to penicillin. A person usually can no longer transmit syphilis 24 hours after starting treatment. Some people, however, do not respond to the usual doses of penicillin. Therefore, it is important that people being treated for syphilis have periodic blood tests to check that the infectious agent has been completely destroyed.

People with neurosyphilis may need to be retested for up to 2 years after treatment. In all stages of syphilis, proper treatment will cure the disease. But in late syphilis, damage already done to body organs cannot be reversed.

What Are The Effects Of Syphilis In Pregnant Women?

A pregnant woman with untreated, active syphilis is likely to pass the infection to her unborn child. In addition, miscarriage may occur in as many as 25 to 50 percent of women acutely infected with syphilis during pregnancy. Between 40 to 70 percent of women with active syphilis will give birth to a syphilis-infected infant.

Some infants with congenital syphilis may have symptoms at birth, but most develop symptoms between 2 weeks and 3 months later. These symptoms may include

  • Skin ulcers
  • Rashes
  • Fever
  • Weakened or hoarse crying sounds
  • Swollen liver and spleen
  • Yellowish skin (jaundice)
  • Anemia (low red blood cell count)
  • Various deformities
People who care for infants with congenital syphilis must use special cautions because the moist sores are infectious.

Rarely, the symptoms of syphilis go undetected in infants. As infected infants become older children and teenagers, they may develop the symptoms of late-stage syphilis, including damage to their bones, teeth, eyes, ears, and brains.

Can Syphilis Cause Other Complications?

Syphilis bacteria frequently invade the nervous system during the early stages of infection. Approximately 3 to 7 percent of persons with untreated syphilis develop neurosyphilis, a sometimes serious disorder of the nervous system. In some instances, the time from infection to developing neurosyphilis may be up to 20 years.

Some people with neurosyphilis never develop any symptoms. Others may have headache, stiff neck, and fever that result from an inflammation of the lining of the brain. Some people develop seizures. People whose blood vessels are affected may develop symptoms of stroke with numbness, weakness, or visual problems. Neurosyphilis may be more difficult to treat, and its course may be different, in people with HIV infection or AIDS.

How Can Syphilis Be Prevented?

The open sores of syphilis may be visible and infectious during the active stages of infection. Any contact with these infectious sores and other infected tissues and body fluids must be avoided to prevent spread of the disease. As with many other STDs, using latex male condoms properly during sexual intercourse may give some protection from the disease.

Screening and treatment of infected individuals, or secondary prevention, is one of the few options for preventing the advanced stages of the disease. Testing and treatment early in pregnancy are the best ways to prevent syphilis in infants and should be a routine part of prenatal care.

reproduced from the National Institute of Allergy and Infectious Diseases

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