Syphilis, the “Great Imitator,” Is on the Rise in the U.S.

“He who knows syphilis knows medicine.”

- William Osler, father of modern medicine

“Perhaps more than any other disease before or since, syphilis in modern Europe provoked the kind of widespread moral panic that AIDS revived when it struck America in the 1980s.”

- Peter Lewis Allen, American author and educator

Syphilis is a sexually transmitted infection (STI) that William Osler referred to as the “Great Imitator” because it can simulate “almost every disease known to man.” In the U.S., a shocking rise in the number of cases of syphilis is accompanying the COVID-19 pandemic. While syphilis is easily treated, many people don’t know they’re infected and without detection and treatment, this STI can have devastating consequences. In this Germ Gems post, I discuss briefly the history of the disease and then the nature of syphilis and reasons for the recent upturn of cases.

Brief history of the disease in Europe. Syphilis was unknown in the Old World until the late 15th Century. According to the “Columbian hypothesis,” navigators in Christopher Columbus’s fleet brought this affliction from the New World back to the Old World on their return in 1493.

At its beginning in Europe, syphilis was a severe, often deadly disease because the population had no immunity against it. (Some have considered syphilis as a justifiable payback, given the fact that explorers carried a number of highly lethal viruses with them, such as smallpox, measles and influenza, that tore through South America killing an estimated 90% of indigenous populations.)

From its beginning, syphilis was stigmatized as a disgraceful disease. Each country whose population was affected pointed the finger at neighboring countries for outbreaks of this infection. For example, inhabitants of today’s Italy, Germany, and the United Kingdom, called syphilis “the French disease”; the French named it “the Neapolitan disease”; the Turks coined the term the “Christian disease”; the Hindus blamed the Muslims; and in the end everyone blamed the Europeans. Ultimately, syphilis became endemic in Europe.

What causes syphilis? It was not until 1905, that Fritz Schaudinn, a German zoologist, and Erich Hoffman, a German dermatologist, discovered the cause of syphilis: the spiral-shaped bacterium Treponema pallidum. Spirochetes are transmitted from person to person by sexual activity, or in the case of congenital infection from mother to baby during pregnancy or at birth.

The four stages of the disease are primary, secondary, latent, and tertiary. The signs and symptoms of syphilis vary depending upon the stage of disease. But sexual transmission by infected people is a threat in all four stages.

The primary stage classically presents with a chancre (a painless skin ulcer or ulcers) in the genital area or mouth. In secondary syphilis, a diffuse rash occurs that frequently involves the palms of the hands and soles of the feet. (A rash in this location is unusual and can be a tipoff to the diagnosis of secondary syphilis.) But in latent syphilis there are few or no symptoms, and this stage of syphilis can last for years.

In tertiary syphilis, “gummas” (soft, non-cancerous growths) occur, and neurological or heart involvement is common. Tertiary infection can appear 10-30 years after a person gets infected and can involve multiple organ systems, including the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints. (The protean clinical manifestations of syphilis explain Osler’s allusion to syphilis as the “Great Imitator.”)

Spirochetes can cross the placenta and infect the fetus starting at about 14 weeks of gestation, and the risk of fetal infection increases with gestational age. Congenital syphilis can manifest with a variety of signs, such as, deformity of the nose (saddle nose), peg-shaped and notched incisors (“Hutchinson teeth”), decreased hearing, an enlarged liver and spleen, jaundiced skin, and a variety of eye diseases, including blindness.

The rise in syphilis cases. According to the Center for Disease Control and Prevention (CDC), the overall number of syphilis cases, including congenital syphilis and syphilis transmitted through sexual contact, rose nearly 70% between 2017 and 2021. The cases increased by nearly 28% in 2021 alone, the second year of the COVID-19 pandemic.

In 2021, the U.S. recorded the highest rate of syphilis since 1990 and the greatest number of overall cases (171,074) since 1951. The increase in congenital syphilis was even steeper than cases transmitted sexually. (Other STIs, like gonorrhea and chlamydia, also saw significant increases, though not nearly as steep as those of sexually-transmitted syphilis.)

The reasons for the increasing number of syphilis cases are manifold and are laid out in a September 28, 2022 PEW Trusts STATELINE article, “’Shocking’ Rise in STIs During COVID Alarms Health Workers.” In this analysis, as well as that of the CDC, COVID-19 contributed to the rise in cases by preventing people from getting routine health care and siphoning public health workers (and funding) for STI work to focus on COVID-19. A lack of sufficient funding for STIs, however, began at least a decade before COVID-19 came long, and these funding shortfalls over the years resulted in the closure of many government-run STI clinics.

Other factors also fueled the increase in STI infections. Foremost among these factors was men having unprotected sex with men and sexually active high school students not using condoms. The opioid and methamphetamine epidemics also spurred risky sexual behavior.

Who should get tested for syphilis and how often. Syphilis can be detected with a simple blood test at a clinic; the test is typically free or inexpensive. Public health experts recommend that health care providers screen all patients who are at increased risk of syphilis, and testing for syphilis should also be performed in people with an illness compatible with the clinical picture of syphilis.

Two of the highest risk groups—men who have sex with men and people with HIV—may benefit from screening more than once one a year. CDC data show that men who have sex with men are 106 times more likely to be infected with syphilis than men who have sex with women. Other groups at increased risk for syphilis include Black Americans, who are nearly five times more likely to be infected than White Americans, and those with limited access to good health care.

All pregnant women should be tested for syphilis early in pregnancy, and those who use drugs should be re-tested in the third trimester and at birth as well. Pertinent to the increase in congenital syphilis cases, David R. Scrase, M.D., secretary of the New Mexico Department of Health, suggests that every encounter with a pregnant woman should be seen as an opportunity to test for syphilis. “We must talk, test and immediately treat those who test positive for syphilis with penicillin to prevent transmission to the fetus. ”

Treatment and prevention. Historically, treatment of syphilis involved using toxic agents containing mercury or arsenic. Fortunately, once penicillin arrived it became, and is still, the drug of choice. (One of the most unethical and maligned studies in the history of medical science was the “Tuskegee Study of Untreated Syphilis in the Negro Male,” carried out in the U.S. in 1932-1972 without informed consent. By this time, penicillin became recognized as highly effective in preventing complications of tertiary syphilis, and withholding treatment with penicillin was unconsionable).

The risk of contracting and transmitting syphilis can be reduced with safe-sex practices including using condoms and being in a monogamous relationship with someone who has tested negative. Until a vaccine is developed and becomes available, safe-sex is of paramount importance in curtailing the alarming upturn of syphilis cases.