Can syphilis really erase memories?

Yes. At an advanced stage, untreated syphilis can cause neurosyphilis, a form in which the bacterium Treponema pallidum crosses the blood-brain barrier and infects the central nervous system. It then causes general paresis, marked by dementia, memory disorders, personality changes, and progressive cognitive breakdown. This form was incurable before the antibiotic era.

Phenomenon medicinemicrobiology

Syphilis: Dementia and Neurosyphilis Explained

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During her visit to the Verdigris Palace, Maomao observes Suirei, a former courtesan whose condition strikes her. She offers a sober clinical assessment: the disease is erasing her memories. The remedy has proven effective in the past, but it is now struggling to help her, and there’s nothing else that can be done. The narration specifies that Suirei had contracted syphilis, that the disease was still in its incubation phase when Maomao’s father first treated her, and that a few years later the symptoms returned and the illness spread rapidly. In a few sentences, the episode describes the disease’s classic progression: a deceptive period of silence, a relapse, then a terminal neurological decline that nothing can reverse.

The subject in depth

Syphilis is a sexually transmitted infection caused by a spiral-shaped bacterium: Treponema pallidum ^[Wikipedia]. It progresses through four distinct phases, the first three of which can pass largely unnoticed, and that is precisely what the story portrays accurately.

Diagram of the four phases of syphilis and the passage of Treponema pallidum into the brain — Four phases, then the passage of Treponema pallidum into the central nervous system

Primary phase. A few weeks after infection, a painless sore (the chancre) appears at the bacterium’s point of entry, then disappears on its own. Many people never notice it.

Secondary phase. Weeks to a few months later, the bacterium circulates throughout the body via the bloodstream. It produces skin rashes, mucosal lesions, and general symptoms resembling an ordinary flu. This phase also resolves on its own, without treatment, and gives way to a silent period.

Latent phase. For months or years, the bacterium persists in the body without producing apparent symptoms. This is the silent incubation period referenced in the episode. The carrier is not cured: Treponema pallidum keeps multiplying in the tissues.

Tertiary phase and neurosyphilis. Left untreated, about a third of infected people develop severe complications after several years. The bacterium reaches deep organs: the heart, major arteries, bones. Above all, it can cross the blood-brain barrier, the membrane that normally shields the brain from infectious agents circulating in the blood ^[Wikipedia]. When Treponema pallidum settles into the central nervous system, this is called neurosyphilis.

The most devastating form of neurosyphilis is general paresis. The brain is progressively destroyed by the infection: neurons die, connections break down. Early signs are memory problems, irritability, and loss of concentration. Then personality disintegrates, dementia sets in, and the patient loses all cognitive autonomy. Without treatment, the outcome is fatal. This is exactly the picture Suirei presents in the episode: a woman whose memory is fading and whom the available remedy can no longer save.

In real life

Before the discovery of penicillin in 1928 and its medical use starting in the 1940s, syphilis was incurable in the modern sense. The only known treatment since the fifteenth century was mercury, administered as skin friction, fumigation, or a drink. Mercury slows the disease’s progression in some patients and can reduce visible lesions, but it is itself extremely toxic: mercury poisoning causes tremors, tooth loss, and neurological and kidney damage. A serious disease was thus treated with a serious poison, in the hope that the bacterium would give in before the body was too damaged. Salvarsan, the first synthetic drug specifically targeting syphilis, was introduced by Paul Ehrlich in 1910; it remained partial and toxic. Only with penicillin did syphilis become truly curable within weeks. Today, the disease can be diagnosed with a simple blood test and treated at an early stage with antibiotics. Neurosyphilis, however, requires hospitalization and high doses of intravenous penicillin; brain damage already done cannot be repaired, but progression can be stopped.

The fact-checker's eye

The work is remarkably accurate. The sequence of silent incubation, relapse of symptoms, rapid spread, and terminal dementia matches point for point the natural history of untreated syphilis. Maomao’s phrasing that the remedy is now “struggling to help her” captures precisely the pre-antibiotic reality: mercury can slow the disease in its early stages but cannot reverse neurological damage once neurosyphilis has set in. The one thing the work leaves in the shadows is the identity of the “remedy,” most likely mercury given the imperial Chinese setting, a subject covered in the entry devoted to that element. Medically, there’s nothing to correct: syphilis really does erase memories, and it isn’t a metaphor.

Note: syphilis is a sexually transmitted infection that can be screened for and treated. If in doubt, getting tested by a doctor or at a sexual health clinic remains the only way to know and to be treated in time.

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Published on May 30, 2026

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