Why did they use mercury to treat syphilis?

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It is a chronic infection that progresses through several stages if left untreated. Syphilis was first definitively described in Europe in 1494 during a major outbreak in Naples, Italy. It quickly became a widespread public health issue across the continent. At the time, there were no effective treatments for the disease. Doctors tried many approaches to curing syphilis, including the use of heavy metals like mercury. Mercury treatments were commonly used to treat syphilis from the 1400s through the early 1900s. Though toxic, the mercury killed the syphilis bacteria and provided temporary relief of symptoms before serious complications could develop.

History of Syphilis

The exact origins of syphilis are unknown. There are two primary hypotheses: one proposes that syphilis was carried to Europe from the Americas by Christopher Columbus and his crew in the late 1400s, while the other proposes that syphilis previously existed in undiscovered forms in the Old World. Regardless of its origins, several major syphilis outbreaks in Europe in the late 15th and early 16th centuries marked the beginning of the Early Modern syphilis epidemic that would afflict Europe for the next several hundred years.

Without any professional medical understanding of venereal diseases, syphilis was commonly misdiagnosed and often confused with other diseases like leprosy. This resulted in very inconsistent early descriptions and terminology. The name “syphilis” was first used by the Italian physician and poet Girolamo Fracastoro in 1530. The name comes from a mythological Greek shepherd named Syphilus who was cursed by the god Apollo. Despite the name syphilis being applied to the disease in 1530, it took several more decades for this term to widely diffuse and replace other common names for the disease.

Syphilis Symptoms and Stages

Syphilis progresses through several stages with distinct symptoms associated with each stage:

Primary syphilis

The first signs of infection appear after an incubation period of 10-90 days following initial syphilis exposure. A painless chancre sore develops, usually in the location where syphilis entered the body (like the mouth, genitals, or anus). The sore lasts 3-6 weeks and heals regardless of whether a person receives treatment or not.

Secondary syphilis

After the chancre heals, infected individuals may experience a rash on the soles of the feet and hands. Other symptoms appear 2-10 weeks after the chancre forms and may include fever, sore throat, fatigue, hair loss, headaches, weight loss, muscle aches, and open sores. These symptoms also resolve in 2-6 weeks as the body temporarily suppresses the infection.

Latent syphilis

After the symptoms of secondary syphilis disappear, syphilis enters a latent phase. At this stage, there are no external symptoms, but the bacteria remain in the body. Latent syphilis is categorized as early latent syphilis (less than 1 year after infection) or late latent syphilis (more than 1 year after infection). Latent syphilis may persist for years before progressing to late stage syphilis.

Late syphilis

In 15-30% of infected persons who do not receive treatment, syphilis will reactivate after the latent stage and progress to serious late stage complications:

  • Tertiary syphilis – characterized by the formation of inflammatory granulomas and gummas in various tissues like the bones, skin, and liver. Other neurological and cardiovascular symptoms may appear.
  • Neurosyphilis – infection of the brain and nervous system leading to dementia and diminished muscle coordination.
  • Cardiovascular syphilis – weakening of the heart muscle and blood vessels.

Without treatment, late stage syphilis can be fatal.

Early Syphilis Diagnoses and Treatment

In the 15th-19th centuries before the microbiological understanding of venereal diseases, syphilis was very difficult to accurately diagnose. The first visible sign of infection, the painless chancre sore, often went unnoticed. When secondary symptoms appeared, they were non-specific and could be indicative of other diseases. Doctors would examine symptoms like rashes, lesions, and lymph node inflammation to make an educated guess on whether a patient had syphilis or something else. This resulted in delayed and inaccurate syphilis diagnoses.

While the bacteria that caused syphilis would not be discovered until 1905, early doctors did recognize that the disease could be treated with compounds containing heavy metals like mercury and bismuth. The first recorded mercury treatment for syphilis dates back to The Middle East in 1350. In 1495, just after the first major European syphilis outbreaks began, the use of topical mercury ointments to treat chancres and skin lesions was noted at the University of Paris. Mercury treatments would become the predominant syphilis therapy for the next 400 years.

Doctors readily prescribed mercury to syphilis patients because the side effects were less severe than the potential complications of late stage syphilis. Mild cases of syphilis that were treated early had a good prognosis. However, more serious cases of late stage syphilis carried a high risk of mortality. Mercury remained the best known option for reducing disease progression and mortality.

Common mercury-based treatments included:

  • Calomel – Mercurous chloride powder dusted on lesions.
  • Blue mass – pills made of elemental mercury, licorice, and honey.
  • Mercury ointments – Topical ointments made with mercury, hog fat, and ammonia.
  • Vapor baths – Patients sat in chambers filled with mercury vapor.
  • Mercury injections – Injections of soluble mercury salts like mercuric chloride.

Problems with Mercury Treatments

While mercury killed the syphilis bacteria, these treatments had many problems:

  • Toxic side effects – Mercury is highly poisonous, so treatments caused side effects like kidney and liver damage, gum disease, loss of teeth, and drooling.
  • Ineffective for late syphilis – If the disease progressed to late stage syphilis, the damaged organs could not be repaired.
  • Poor dosing – Doctors often gave too much mercury, leading to toxicity side effects.
  • Temporary relief – Symptoms would return after ending a treatment regimen requiring long-term therapy.
  • No cure – Mercury helped ease symptoms but did not fully eliminate the infection.

Rise of Ehrlich’s Salvarsan Treatment

The problems with mercury treatments led doctors to continue researching other potential cures for syphilis. In 1905, German bacteriologist Fritz Schaudinn identified the spirochete bacterium Treponema pallidum as the cause of syphilis. This discovery enabled German chemist Paul Ehrlich to begin developing targeted compounds to kill the bacteria.

In 1909, Ehrlich discovered the drug Salvarsan, an arsenic-based compound. Salvarsan was the first known chemotherapeutic drug – a medicine capable of killing microorganisms without severely affecting the patient. Clinical trials showed it was highly effective at treating all stages of syphilis with reduced side effects compared to mercury. Salvarsan was approved for medical use later that year.

Salvarsan was often administered intravenously. Patients required fewer injections than mercury treatments. While not explicitly a cure, Salvarsan provided a stronger therapeutic effect than mercury and remained the predominant treatment for syphilis until Penicillin replaced it in the 1940s. Even after Salvarsan ended the reign of mercury, mercury treatments were still used in some areas where Salvarsan was unavailable. Mercury was also used to treat neurosyphilis into the 1950s.

Public Health Advancements to Combat Syphilis

Public health initiatives were also critical for controlling the syphilis epidemic. Efforts included:

Education Campaigns

Health departments educated the public about transmission and prevention by promoting monogamy and condoms.

Regulation of Prostitution

Brothels were periodically closed during outbreaks to prevent transmission. Prostitutes were often forcibly examined and confined if infected.

The Wassermann Test (1906)

Developed by German bacteriologist August von Wassermann, this was the first effective screening test for syphilis. It enabled earlier detection.

Contact Tracing

Health officials interviewed infected people to identify sexual partners for testing and treatment.

Mass Treatment Campaigns

Entire populations were treated during some outbreaks in an attempt to eliminate disease reservoirs.

Penicillin and the Modern Syphilis Landscape

The advent of Penicillin in 1928 rapidly transformed the outlook for syphilis patients. Penicillin provided an affordable, widely available antibiotic capable of definitively curing all stages of syphilis with negligible side effects if taken correctly. By the 1950s, syphilis cases had declined dramatically in countries with access to Penicillin.

Syphilis is still with us today as a treatable but serious venereal disease. With Penicillin, it is easily cured if diagnosed early. Without treatment, late stage syphilis still can occur and result in dire health consequences. Public health organizations currently focus efforts on encouraging at-risk groups to get tested regularly to prevent transmission and late stage infections. They also watch out for any signs of increased antibiotic resistance in syphilis strains.

Conclusion

From its mysterious origins to the modern antibiotic era, syphilis has a long and deadly history as one of humanity’s most notorious infections. For centuries, doctors tried many ineffective and sometimes dangerous remedies to treat the disease. The use of mercury treatments emerged as the first semi-effective option for reducing syphilis symptoms and mortality before late stage complications could develop. Despite major problems with toxicity, insufficient dosing, and inability to cure syphilis, mercury remained the standard syphilis treatment for over 400 years before Paul Ehrlich’s discovery of the arsenic-based Salvarsan treatment in 1909.

Public health efforts also played a major role in controlling the spread of syphilis outbreaks. However, it was not until the mass production of Penicillin in the 1940s that humans finally developed a true cure for syphilis free of major side effects. While syphilis remains an important public health concern today, it serves as an example of the dramatic progress that can be made against a disease that was once a certain death sentence. Our steadily increasing medical knowledge has transformed syphilis from its fearsome reputation in the past into a manageable infection today.

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