Syphilis

Today we discussed syphilis. Some points about this infection that has made a resurgence:

Treponema pallidum (spirochete), is spread through contact with infectious lesions or fluids. 50-75% of exposed sex partners get infected.

Clinical manifestations (NB- syphilis is the "great imitator"; these are the more common presentation, but keep a high index of suspicion in the right epidemiological setting)

Primary:
-skin lesion (chancre) at site of innoculaion ~21d after exposure. Often goes unnoticed. Classically non-tender, indurated, non-purulent. Heals spontaneously.

Secondary:
-4-10 weeks after chancre appearance. Rash in 90%; pink, red, or purpule macules on flanks, shoulders, arms, chest, back. May become maculosquamous/papular and affect hands/soles in 50-80%.
-other signs/symptoms include sore throat, malaise, h/a, lymphadenopathy. Can cause neurologic, renal, ophthalmologic, GI, hepatic disease. Resolves without treatment, may recur.

Tertiary:
Years later- aortitis, gumma (mass), iritis.

A word about neurosyphilis:
Neurosyphillis can occur early or late. May coexist with primary, secondary, or tertiary. May see meningitis, cranial nerve involvement, eye involvement, meningoencephalitis, meningovascular (presents as stroke). Late findings are rare; occur decades later: paresis, dementia with psychosis (rapidly progressive), tabes dorsalis (posterior column involvement, bowel, bladder dysfunction).

LP indicated in any of 1) neuro/ocular/otic symptoms/signs. 2) biochemical evidence of late latent syphilis (or unknown duration) in HIV pt. 3) active tertiary- gumma, aortitis, iritis. 4) treatment failure for non-neurosyphilis

Lab testing
The lab testing for syphilis is very complex and confusing. Here are some general comments; click here for detailed interpretation from the Ontario Public Health Lab website

NB- RPR is essentially synonymous with VDRL
1) EIA (enzyme immunoassay), TPPA, FTA-Abs. All of these are durable antibody tests that are very sensitive, and remain positive for life. If negative, syphilis is usually ruled out. If positive, need confirmatory testing (there are false positives)
2) RPR- This is also an antibody test, but more suggestive of active infection. If postive, this confirms diagnosis. If negative, it can mean 1 of several things: a) very early primary- retest in 2 weeks. b) successful treatment. c) late latent d) biologic false positive

Treatment:
NB- latent =seroreactivity without clinical manifestations. Early is infected within previous year by documented conversion. Late is over 1 year from primary infection

Primary, secondary, early latent: Pen G 2.4M U IM single dose
Late latent, unknown, tertiary: Pen G 2.4M U IM qweekly x 3.
Neurosyphilis, ocular, otic: Pen G IV 18-24M units/d divided q4h for 10-14d.

NB- need repeat serology to confirm/document treatment success- see paper below for details

Primary should have RPR negative at 1 year. Secondary at 2 years. Tertiary at 5 years.

Links:
Click here for a JAMA review of syphilis that most of this post is based on
Click here for the Ontario Public Health Lab algorithm for interpreting the MANY permutations and combinations of lab results