Congenital Syphilis

In US primary, secondary and cong syphilis all surged in the 90s, now focal outbreaks in urban, drug using population. In N Africa, 3% of pregnancies, up to 7% in Carribean. 1 million pregnancies affected worldwide, of which 50% will end in abortion or still birth, and the other 50% will be congenital cases (unlike TORCH).

Clinically, 2/3 affected neonates asymptomatic at birth. Otherwise:

  • “snuffles” (vesicles on upper lip, highly infectious)
  • mucous patches (moist erosions)
  • hepatosplenomegaly and hepatitis
  • anaemia +/- hydrops
  • meningitis, with CSF pleocytosis and high protein
  • pneumonia, +/or fluffy diffuse infitrates on CXR (=pneumonia alba)
  • pseudoparalysis

Years later:

  • Typical facies – frontal bossing, saddle nose, short maxilla, high palate
  • Mulberry Molar (5 blobs in ring shape to tooth, pathognomic!). Hutchinson’s incisors (peg-like) better known.
  • Gummata (rubbery ulcers)
  • Sabre tibia (anterior bowing)
  • Hutchinson’s triad = interstitial keratitis, peg shaped incisors, and sensorineural deafness.

Prevention

The risk of transmission is very high, particularly for untreated primary (ie a chancre) or secondary (ie multiple lesions, lymphadenopathy) disease. The risk falls to 40% for early latent syphilis (ie test positive but asymptomatic, with infection likely to have occurred in the previous 12 months on the basis of previous tests, symptoms or exposure). A category exists of latent syphilis of unknown duration, which only applies to patients aged 13-35yrs with nontreponemal titre of 32 or more.

Treating syphilis in pregnancy – for early acquired disease (primary, secondary or latent of <1yr) benzathine penicillin 50 000U/kg, with second dose a week later if in third trimester [BNF] but exclude neuro. For late latent syphilis >1yr duration give 3 doses at weekly intervals. For neuro disease benzylpen 50 000U/kg qds for 10-14/7 followed by 3 doses benzathine penicillin as above. If HIV positive also, then there tends to be more CNS disease, treatment failure, and treatment reactions (fever, myalgia, preterm labour – give steroids).

Adequate antenatal treatment = adequate benzathinepenicillin dose (2.4M Units IM) once weekly x3 – erythromycin is not reliable), 30 days before birth, proven 4x drop in nontreponemal serology.

Diagnosis

Syphilis tests are either nontreponemal or treponemal.

  • Nontreponemal viz VDRL, RPR are screening tests, 70% sensitive in primary, 99% in secondary.
    • False positives – lupus, infection, recent immunization, pregnancy, other treponemes.
    • Quantitative – correlate with disease activity: 4x rise in titre early on or in relapse, drop of 4x suggests adequate response to treatment. In secondary, titres are always high ie 1:32.
    • False negative – early? Tertiary – V high levels of antibody! So if high suspicion then do dilutions.
    • Should become negative within 1 yr of treatment in primary, 2 yrs in secondary or congenital, 5 yrs in late.
  • Specific treponemal tests eg TP immobilization (TBI), fluorescent T antibody absorption (FTA-Abs) used to confirm.
    • False positive with non pallidum, Lyme or other borrelia.
    • Remain positive for life, even with treatment.
    • Do not correlate with disease activity.
    • FTA-Abs IgM available for testing baby, but still has false positives/negatives

In newborns, direct microscopy and fluorescent antibody tests can be done from mucous patch, else from placenta (beware non pallidum treponemes in normal flora esp mouth). PCR can be done from lesions too. VDRL more than 2x dilutions richer than mum’s is suggestive. IgM can be negative early esp infection occurring late in pregnancy, not always recommended. False positive VDRL may occur due to transplacental antibodies if high maternal levels.

Where disease is likely, or maternal treatment has been inadequate, further testing is required:

  • FBC, LFTs
  • Lumbar puncture, incl VDRL on CSF (not 100% sensitive so if congenital disease suspected, treat for neuro.)
  • XR long bones to look for destructive lesions. Even in asymptomatic, XR changes seen in 20% esp ankles, knees but also wrists, elbows. Lesions are symmetric, multiple: periostitis, osteitis, osteochondritis.
  • CXR
  • Ophthalmology assessment

For screening adults, 1 step strip test available, and one off oral treatment (Azithro, 1.8g). Antibodies give only partial protection.

Treatment

For congenital syphilis treat with benzylpen 100-150 000 U/kg/d in bd or tds doses for 10-14/7.

There is concern about CSF levels with procaine or benzathine penicillin, although sometimes these are used for asymptomatic babies with nontreponemal tests less than 4x mum’s, which might occur with inadequate treatment. In this situation, any abnormal finding on evaluation requires full 10/7 course.

If late diagnosis (>4/52), give high dose viz 200-300 000 U/kg/d qds for 10-14/7. If CNS disease is excluded, this could be converted to benzathine penicillin.

Follow up

Monitor to show fall in VDRL at 3-6 months.

(Rana Chakraborty, St George’s)

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