Syphilis

Stages

• Primary syphilis typically presents around 3 weeks post-exposure with a firm, painless chancre at the inoculation site and regional lymphadenopathy

• Secondary syphilis generally occurs around 6 weeks post-exposure with systemic features including fever, malaise and a rash often involving the palms and soles, along with generalized lymphadenopathy and possible neurological signs such as cranial nerve palsies or meningitis

• Latent syphilis is divided into early latent (infectious, within 2 years) and late latent (generally non-infectious though congenital transmission remains a risk)

• Tertiary syphilis, which may develop months to years after initial infection if untreated, is characterised by gummatous lesions, cardiovascular involvement and neurosyphilis such as tabes dorsalis

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Diagnosis

• Diagnosis is based on a combination of clinical history, physical examination and laboratory testing

• Non-treponemal tests such as RPR or VDRL are used for screening and monitoring treatment response, expecting a fourfold titre decline with successful treatment

• Treponemal tests (eg EIA, TPPA, TPHA, FTA-ABS) confirm diagnosis and typically remain positive for life

• In early syphilis, serology may be negative during the window period; direct detection using T. pallidum PCR from ulcer swabs can be useful

• A reactive treponemal test with a non-reactive non-treponemal test may indicate early infection or previously treated syphilis, while a fourfold rise in RPR titre suggests re-infection

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Treatment

• Early syphilis (primary, secondary and early latent <2 years) is treated with a single intramuscular dose of benzathine penicillin G 2.4 million units

• Late latent syphilis (>2 years) or tertiary syphilis without neurosyphilis is treated with benzathine penicillin G 2.4 million units IM weekly for 3 weeks

• Neurosyphilis requires intravenous benzylpenicillin 1.8 g every 4 hours for 15 days

• In patients with penicillin hypersensitivity, doxycycline 100 mg orally twice daily for 14 days is an alternative in non-pregnant individuals; pregnant patients should undergo desensitisation and receive penicillin

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Jarisch-Herxheimer Reaction

• Typically occurs 6–12 hours post-treatment with fever, chills, headache and myalgia

• Management is supportive, using analgesia and rest

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Partner Notification and Follow-Up

• All sexual contacts should be treated presumptively regardless of their serology

• Contact tracing is advised for the past 3 months in primary syphilis, 6 months in secondary, and 12 months in early latent syphilis

• Follow-up serology is recommended at 3, 6 and 12 months to ensure a fourfold decline in nontreponemal titres and to detect potential re-infection

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Notes

• Syphilis incidence is increasing in Australia, particularly among Aboriginal and Torres Strait Islander populations and men who have sex with men; high-risk patients should be managed promptly without waiting for laboratory confirmation

• Pregnant women with syphilis require specialist input to reduce the risk of congenital syphilis and should be treated with penicillin after desensitisation if hypersensitive

• In patients with HIV infection, there is an increased risk of neurosyphilis; careful clinical and serological monitoring is essential, with cerebrospinal fluid analysis considered if treatment response is inadequate

• Document curative treatment clearly in the patient’s medical history, as treponemal tests remain reactive for life despite successful treatment