Incubation Period for Syphilis
The incubation period for syphilis is typically 2-8 weeks after primary inoculation, with progression to secondary syphilis occurring during this timeframe. 1
Timeline of Disease Progression
Primary syphilis develops after an incubation period of approximately 2-8 weeks following initial exposure to Treponema pallidum. 1 This represents the time from inoculation to the appearance of the primary chancre.
The primary chancre appears at the site of contact as a single painless nodule that rapidly ulcerates, though multiple or atypical chancres may occur, particularly in HIV-infected individuals. 1
Secondary syphilis typically follows 2-8 weeks after primary inoculation, meaning it can overlap with or follow shortly after the primary stage. 1 This stage is characterized by systemic manifestations including rash, lymphadenopathy, and constitutional symptoms.
Clinical Implications for Diagnosis and Treatment
Partners exposed within 90 days prior to diagnosis should receive presumptive treatment even if seronegative, as they may be infected but not yet showing serologic evidence of disease during the incubation period. 2 This is critical because early infection may not produce detectable antibodies.
The recommended prophylactic treatment is benzathine penicillin G 2.4 million units IM in a single dose, identical to treatment for primary and secondary syphilis. 2
Important Caveats
HIV co-infection may accelerate disease progression and make clinical lesions more apparent, potentially shortening the typical incubation timeline. 1
Serologic testing may be negative during early incubation, which is why presumptive treatment is recommended for recent exposures rather than waiting for serologic confirmation. 2
All patients with syphilis exposure should be tested for HIV, as co-infection is common and may alter disease presentation. 2