Syphilis Facts

What is Syphilis?

Syphilis is a sexually transmitted infection (STI) spread by direct contact during vaginal, anal or oral sex. If left untreated, it can cause brain, nerve and tissue damage, and death.

Syphilis Is On The Rise In Colorado

  • Syphilis cases are rising in Colorado and throughout the United States
  • In Colorado, the number of overall cases of syphilis tripled from 2018 to 2023
  • Congenital syphilis, which is caused when a mother with syphilis passes the infection to her baby during pregnancy, has increased by 7 times from 2018 to 2023 with a total of 50 cases in Colorado in 2023

The state health department has recommended increased syphilis testing in response to the increase in cases.


The average time between acquiring syphilis and the start of the first symptom is 21 days. However, initial symptoms can appear anywhere from day 10 to day 90 of infection, and many people will not notice any symptoms at all.

Syphilis infection is divided into different stages: primary, secondary, latent, and tertiary. Each stage can have different signs and symptoms.

Primary Stage

  • A single or multiple sores that are typically firm, round, and painless occurring on the penis, vagina, anus, rectum, lips, or in the mouth.

Secondary Stage

  • Typically red or reddish-brown non-itchy skin rashes or sores on the trunk, hands, and/or feet.
  • Large, raised, gray or white lesions in the mouth
  • Fevers, swollen lymph nodes, sore throat, patchy hair loss, headaches, weight loss, muscle aches, and fatigue

Latent Stage

  • A period when there are no visible signs or symptoms but the infection is still present.

Tertiary Stage

  • May occur 10-30 years after the infection began, causing damage to organs and possibly death.

Congenital Syphilis

Congenital syphilis is a disease that occurs when a mother with syphilis passes the infection to the baby during pregnancy. The infection can be transmitted at any stage of syphilis.

Syphilis can affect a baby by causing the following complications:

  • Miscarriage (losing the baby during pregnancy)
  • Stillbirth (a baby born dead)
  • Prematurity (a baby born early)
  • Low birth weight, or
  • Death shortly after birth

For babies born with congenital syphilis, they may develop the following problems:

  • Deformed bones
  • Severe anemia (low blood count)
  • Enlarged liver and spleen
  • Jaundice (yellowing of the skin or eyes),
  • Brain and nerve problems like blindness or deafness
  • Meningitis
  • Skin rashes

Getting tested and treated for syphilis can prevent serious health complications in both mother and baby. Syphilis treatment during pregnancy can prevent transmission of the infection to the baby.

Testing and Treatment

Syphilis is detected using a simple blood test and is easily curable. You can schedule an appointment with your primary care provider or call the Denver Sexual Health Clinic at 303-602-3540 to set up an appointment. Convenient syphilis testing sites are also located throughout the Denver metro area.

We recommend syphilis screening in the following situations:

  • All pregnant people at the first prenatal visit, early in the third trimester (28-32 weeks gestation), and at delivery
  • All pregnant people in correctional facilities also at first prenatal visit, early in the third trimester (28-32 weeks gestation), and at delivery
  • Infants born to any person who did not have prenatal care or syphilis testing before delivery
  • Men who have sex with men at least every year, or every 3-6 months depending on risk factors
  • Sexually active people living with HIV at first HIV visit, and at least every year thereafter
  • People who have partner(s) who have tested positive for syphilis (immediately)

Syphilis screening should be offered to all sexually active people ages 15-44 years-old.

What to do if you test positive

  • Don’t worry. Syphilis can be cured with antibiotics.
  • Abstain from sex until sores are healed and your course of antibiotics is complete.
  • Contact all sex partners so they can be tested.

How to protect yourself and others

Syphilis symptoms aren’t always obvious. Protect yourself by:

  • Getting tested routinely for STIs.
  • Practicing safer sex—talk to your partners about STIs before you have sex and use condoms if you or your partner have multiple partners.
  • Avoiding sex if you see sores or other a rash, especially in the groin area.

What is the link between syphilis and HIV?

Oral, anal, vaginal, or penile syphilis sores make it easier to transmit and acquire HIV infection. A person is 2 - 5 times more likely to get HIV if exposed when syphilis sores are present.

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