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Pictured Above: The bacteria that cause syphilis are shaped like corkscrews. Image: David Cox, CDC

Last month, a “weird” medical case made headlines. An Australian man with unexplained headaches and eye pain got a diagnosis for his mysterious symptoms when his doctors discovered he had syphilis — and the infection had spread to his head. Syphilis had caused both optic nerves to become swollen, triggering pain that worsened whenever he moved his eyes.

It might seem strange that a disease most people associate with below-the-belt symptoms can wreak havoc above the neck, but syphilis is a wanderer that can travel all over the body, sowing chaos wherever it goes.

Syphilis can quickly enter the nervous system and travel to the head, where it can cause blindness, psychiatric problems, and other trouble.

Ocular Syphilis

The bacteria that cause syphilis can be passed from one person to another through contact with a sore, which can appear on or around the mouth, genitals, or anus. Any type of sexual contact, including oral sex, can transmit these bacteria. Sores are painless, contain a highly infectious liquid, and can appear between three weeks to three months after infection. These sores aren’t always visible, which means you can’t tell if someone has syphilis just by looking at them.

Although the bacteria typically land in the mouth, genitals, or anus, they can also be sexually transmitted directly into the eye, causing redness and vision problems. After infection, syphilis sores can appear on the eyelids, tear ducts, and soft tissues around the eyes. Bacteria can also travel to the eye by entering the nervous system and blazing a trail to the optic nerve — no direct contact between the eye and a sore necessary.

Pictured Right: Eye, FDA.gov

An ocular infection with syphilis can lead to scarring and, ultimately, to blindness, so prompt treatment is important. Unfortunately, it might be difficult to receive a diagnosis, as sexual health professionals might not always be paying attention to the

eyes, and ophthalmologists might not be thinking of STDs when caring for patients. Also, if symptoms are mild, many patients won’t be sufficiently bothered by them to seek medical care in the first place. The man in Australia suffered through his headaches for three weeks before seeing a health care provider.

Though ocular syphilis is rare, it is, unfortunately, on the rise, along with syphilis as a whole. While ocular syphilis can do permanent damage to the eyes if not caught in time, it can be treated with penicillin. If caught early enough, damage to the eyes can often be reversed.


After infection, the bacteria that cause syphilis can quickly enter the nervous system to move all around the body, leading to symptoms that are a far cry from those of a typical STD. When syphilis invades the nervous system, it’s called neurosyphilis.

A common myth is that it takes years — a decade or more — for untreated syphilis to reach the head. But actually, a simple syphilis infection can enter the nervous system in a matter of days. And, while neurosyphilis usually doesn’t have symptoms in the early stage (during the first two years), it can potentially invade the membranes that enclose the brain and spinal cord to cause headaches, stiff necks, blindness and other vision problems, deafness (often preceded by tinnitus), and more. It can also affect the central nervous system, potentially causing muscle weakness or partial paralysis on one side of the body, seizures, and language impairments.

After those first two years, syphilis enters a later stage, and at this time, the infection can manifest in new ways. One manifestation of late-stage syphilis, called general paresis, doesn’t show up until a decade or more after the initial infection. This form of the disease causes dementia, which can sometimes include dramatic personality changes, hallucinations, and manic delusions. General paresis is the form of syphilis that, to this day, is most infamous for addling the minds of many of the pre-antibiotic era’s favorite geniuses, including (supposedly) Vincent Van Gogh, Oscar Wilde, Beethoven, and Mozart.

Late-stage syphilis can also lead to serious damage in the spinal cord and nervous tissues, causing tabes dorsalis, characterized by muscle weakness and abnormal sensations, including “lightning pains.” It can cause difficult walking and other coordination problems, resulting in a staggering, unsteady gait.

The Importance of Getting Tested

In the days before antibiotics, only 10% to 20% of people with syphilis actually progressed far enough in their diseases to develop late-stage neurosyphilis — we don’t know if the risk is the same for untreated people these days. HIV infection, however, could hasten the onset of neurosyphilis symptoms, and might make treatment more difficult.

Fortunately, the Australian man’s symptoms went away after completing a two-week course of intravenous penicillin, and it seemed that no permanent damage was done to his vision. But his experience highlights the importance of practicing safer sex and getting tested for STDs regularly. He was on Truvada — aka PrEP — to reduce his risk of catching HIV, but that medication doesn’t protect against other STDs, and he was exposed to syphilis when he engaged in condomless sex with a partner. Condoms and dental dams are still the best way for sexually active people to protect themselves from a range of sexually transmitted pathogens.

The good news is that ocular syphilis and serious manifestations of neurosyphilis are rare in the United States. But, since the stakes are so high, it’s important that sexually active people know their status. 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. The infection can lead to serious damage or death, but it’s easily detected and cured, so get tested!

Tags: condom, syphilis, HIV, sexually transmitted infections, Prep, sexual health, STD Awareness

About Anna C.

Anna first volunteered for Planned Parenthood as a high school student in the 1990s. Since then, she has received a bachelor’s degree from UC Berkeley and a master's degree in epidemiology from the University of Arizona. As an ode to her fascination with microbes, she writes the monthly STD Awareness series, as well as other pieces focusing on health and medicine.

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