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Syphilis

GMJ News knowledge hub · last reviewed August 2026 · Georgian Medical Journal

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Syphilis — caused by Treponema pallidum — caused 7.1 million new infections and 133,000 deaths in 2020, with congenital syphilis (maternal transmission to the fetus) causing 710,000 cases including stillbirth, neonatal death and permanent disability, yet remaining treatable with benzathine penicillin G — a drug available since 1943 (WHO). Syphilis is experiencing a global resurgence: in the US, congenital syphilis increased 10-fold between 2014 and 2022 (362 to 3,882 cases) — a preventable tragedy. The classic four-stage presentation (primary chancre → secondary rash → latent → tertiary cardiovascular/neurosyphilis) makes syphilis the “great imitator” — among the most diagnostically challenging infections in medicine.

Key messages

7.1M new infections — 10x congenital surge in USA
Syphilis caused 7.1 million new infections and 133,000 deaths in 2020. In the USA, congenital syphilis increased 10-fold between 2014-2022 — a preventable tragedy from missed antenatal screening (WHO).
The great imitator — 4 stages
Syphilis progresses through four stages: primary (painless chancre); secondary (generalised rash including palms/soles, condylomata lata); latent (asymptomatic); and tertiary (cardiovascular syphilis, gummas, neurosyphilis). Each stage has distinct clinical features — no other infection mimics so many diseases.
Benzathine penicillin — still fully effective
Benzathine penicillin G remains the gold standard treatment for all stages of syphilis — remarkably, T. pallidum has developed NO resistance to penicillin in over 80 years of use. Single IM dose for early syphilis; 3 weekly doses for late latent.
Congenital syphilis — a preventable tragedy
Maternal syphilis causes stillbirth, neonatal death, bone/tooth deformities, sensorineural deafness, saddle nose deformity and neurosyphilis in neonates. Antenatal syphilis screening and treatment in the first half of pregnancy prevents virtually all congenital syphilis.
Syphilis and HIV
Syphilis and HIV are closely linked: genital ulcers (chancres) dramatically increase HIV transmission and acquisition (approximately 3-5 fold). Syphilis accelerates HIV disease progression; HIV alters syphilis serology and clinical presentation, making diagnosis more difficult.
Non-treponemal + treponemal serology
Diagnosis requires two-stage testing: non-treponemal tests (RPR or VDRL — quantitative, used to monitor treatment response); confirmed by treponemal tests (TPHA, FTA-ABS, TPPA — qualitative, remain positive for life after treatment).

Key statistics

7.1M
new syphilis infections in 2020 (WHO)
WHO 2020
133K
syphilis deaths per year
WHO 2020
710K
congenital syphilis cases/year globally (WHO 2020)
WHO
10x
increase in US congenital syphilis 2014-2022
CDC
0
penicillin resistance documented in T. pallidum after 80 years
WHO
3-5x
increased HIV transmission risk from syphilitic ulcers
WHO

Syphilis — four clinical stages and key features

Source: WHO. Syphilis stages progress over months to years; tertiary syphilis appears years after untreated infection.

Glossary of key terms

Treponema pallidum
WHO
A thin, spirochaete bacterium — obligate pathogen, cannot be cultured on artificial media. The causative agent of syphilis (subsp. pallidum), yaws (subsp. pertenue), bejel (subsp. endemicum) and pinta (subsp. carateum).
Primary chancre
WHO/Clinical
A painless, indurated (firm), well-defined ulcer with clean base — at the site of T. pallidum inoculation (genitalia, anus, mouth). Highly infectious; heals spontaneously in 3-6 weeks regardless of treatment. Regional painless lymphadenopathy accompanies.
Secondary syphilis
WHO
Haematogenous dissemination of T. pallidum — classically causing a generalised maculopapular rash including the palms and soles (pathognomonic) + condylomata lata (flat wart-like lesions in moist areas) + mucous patches + systemic symptoms (fever, lymphadenopathy, headache, myalgia). Any organ can be involved.
Neurosyphilis
WHO/Neurology
T. pallidum invasion of the CNS — occurring at any stage. Forms: asymptomatic (CSF abnormalities without symptoms); meningitis (early secondary); meningovascular (stroke from endarteritis); parenchymatous (tabes dorsalis — posterior column degeneration; dementia paralytica — frontal lobe). Treated with IV benzylpenicillin 14 days.
Congenital syphilis
WHO/Maternal
Vertical transmission of T. pallidum to the fetus after 16 weeks of pregnancy (when fetal immunocompetence develops). Early congenital syphilis (0-2 years): hepatosplenomegaly, rash, snuffles, bone lesions, haemolytic anaemia. Late (>2 years): Hutchinson triad (interstitial keratitis, Hutchinson teeth, 8th nerve deafness); saddle nose; sabre shins.
Jarisch-Herxheimer reaction
WHO
A transient febrile reaction occurring within 2-8 hours of the first penicillin dose for syphilis — caused by massive release of spirochaetal antigens and cytokines. Fever, chills, myalgia, headache lasting 12-24 hours. Not an allergic reaction. In pregnant women, may trigger preterm labour — warn patients, do not withhold treatment.

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Related health topics

STIsGonorrhoeaHIV/AIDSMaternal healthCongenital infectionYaws (related treponema)

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