STI Awareness: Syphilis

Treponema pallidum, the causative agent of syphilis, is seen in this electron micrograph adhering to a surface with the end of its structure. Image: Public Health Image Library, CDC

When syphilis first descended upon Europe, it was seen as a new plague, and anxiety and blame coalesced around this mysterious scourge. Was it a punishment from God? Was it introduced by a hated Other? Was it caused by the stars’ alignment or the presence of “bad air”? The panic it provoked foreshadowed the hysteria that surrounded the emergence of HIV in the 1980s, as syphilitics were discriminated against, feared, or thought to have received punishment for their “unbridled lust.”

We now know that syphilis is not caused by supernatural forces, foreigners, or “bad air,” but rather by a species of spiral-shaped bacteria called Treponema pallidum, which can cause infections in the vagina, anus, urethra, or penis, as well as the lips and mouth. It is mostly spread by sexual contact – vaginal or anal intercourse, as well as oral sex – in which one person comes into contact with a syphilis sore. These sores can be hidden on the cervix or in the vagina, urethra, rectum, or mouth, making it not immediately apparent that one is infected with syphilis. Syphilis can also spread to a fetus during pregnancy. Sexually active people can reduce their risk of contracting syphilis by using latex barrier methods such as condoms or dental dams.

Syphilis’ initial symptoms, if present, can be mild, and can include a painless sore or an ulcer, called a chancre, which can appear after about three weeks of infection (but can take as long as three months). These sores contain a liquid that is highly infectious, making early-stage syphilis extremely contagious – the presence of sores also increases risk for HIV transmission. Three to six weeks after the sores appear, other symptoms that characterize the secondary stage of infection may appear. They include lesions, as well as rashes on the body, usually on the soles of the feet or the palms of the hand. Other symptoms include fever, sore throat, hair loss, weight loss, swollen glands, and muscle pain.

According to the Centers for Disease Control and Prevention, 15 percent of people infected with untreated syphilis reach the late stage, which can occur up to 20 years after initial infection. It includes severe damage to the nervous system, brain, heart, or other organs, and can be fatal. Symptoms can include difficulty coordinating movement, numbness, paralysis, weakening eyesight, or dementia. It can also lead to gummatous syphilis, in which severe inflammation leads to complete destruction of areas of the skin, bones, and other organs.

Written records of syphilis date back to 1495 when it seemed to appear in Europe for the first time. To differentiate it from smallpox, syphilis was called the Great Pox – according to a 1519 description it caused

Boils that stood out like Acorns, from whence issued such filthy stinking Matter, that whosoever came within the Scent, believed himself infected. The Colour of these was of a dark Green and the very Aspect as shocking as the pain itself, which yet was as if the Sick had laid upon a fire.

Interestingly, such descriptions don’t match modern forms of syphilis, which is mild at least compared to its apparent earlier manifestation. This suggests that the disease might have evolved into a less virulent form, possibly in response to selective pressure against symptoms that render the host sexually unappealing; the pustules of yore don’t seem to decorate the epidermis of contemporary sufferers, making them more likely to perpetuate the milder form of syphilis through sexual transmission. This is not to suggest that syphilis can safely be left untreated! As we saw above, untreated syphilis can lead to severe tissue damage and is potentially fatal.

For centuries, syphilis had no effective cure. The best available treatment consisted of continual doses of mercury, which slowed the disease’s progression but was toxic to humans as well. It wasn’t until 1910 that scientists led by Paul Ehrlich synthesized an arsenic-based chemical that was marketed under the trade name Salvarsan. While it was certainly several steps up from mercury, it had to be given in small doses to avoid its toxic effects; it also had many unpleasant side effects, ranging from rashes to liver damage. Two years later, Neosalvarsan was released, with milder side effects, and was hailed as a “magic bullet” by journalists.

Unfortunately, this treatment regimen could take weeks, months, or even more than a year to administer, and it involved not just arsenicals but compounds based on mercury and bismuth as well, all with their own dangerous side effects. Malaria fever therapy, popular from the 1920s until the adoption of penicillin as a cure for syphilis, was used on patients with an advanced form of the infection, based on the idea that infecting a patient with malaria would induce a fever that could somehow kill T. pallidum. In the meantime, although arsenic-based therapies improved, such treatments were too expensive for most patients, and the long-term regimen was off-putting for many. This helped keep a great number of quack doctors in business. Various tonics, “blood purifiers,” treatments involving electric shock, and other alternative remedies were popular, but ultimately ineffective. Unfortunately, because syphilis goes into a latent phase, many people undergoing such treatments believed they had indeed been cured. As a health official noted in 1937,

[Q]uacks flourish and the sale of patent medicines for syphilis has become big business because even the severe and recognizable early symptoms usually are transitory. No matter what nostrum is taken; no matter how inadequate the treatment given, eventually these early signs and symptoms of the disease disappear. When they disappear, thousands of syphilis victims think themselves cured, not realizing that instead of cure, this marks the end of the period when the best chance for it is possible.

Although treatment for syphilis and other STIs is more accessible and effective than it was a century ago, bogus cures still abound, taking advantage of people’s embarrassment over receiving treatment from a medical provider.

The spiral-shaped members of Treponema pallidum cause syphilis. Here the bacterium is magnified 36,000 times by an electron microscope. Image: Public Health Image Library, CDC

Treponema pallidum, the organism responsible for syphilis, moves through mucus or the bloodstream in a corkscrew-like motion. As you can see in the picture above, the way it is shaped allows it to attach to a host cell by “hooking” onto its surface. It has one of the smallest genomes of any bacteria species, but despite its simplicity, it is difficult to culture outside of a human host, making it tricky for microbiologists to determine what exactly allows it to harm us. Like the bacteria that cause gonorrhea, members of T. pallidum have multiple copies of the gene coding for the proteins that allow them to adhere to human cells – perhaps, as in the case of gonorrhea, these genes allow T. pallidum to alter their surface proteins in order to escape recognition by the immune system. Additionally, T. pallidum produces lipoproteins, which are thought to elicit an inflammatory response that ultimately leads to tissue damage. Our immune systems, for whatever reason, don’t seem to respond aggressively to T. pallidum’s outer lipid layer, earning it the nickname “Teflon pathogen.”

Diagnosis is usually obtained either by testing the blood for antibodies or observing the products of a suspected syphilis lesion under a microscope. In its early stages, syphilis is easily treated with an antibiotic such as penicillin. If it is not caught until its later stages, any damage done to your body cannot be reversed, so it is important to be tested if you are at risk. If you are concerned that you might have syphilis, you can get tested at a Planned Parenthood health center, as well as other clinics, private health-care providers, and health departments. Further information can be found on the CDC’s website.