Congenital Syphilis
BULLETIN FOR MEDICAL PRACTITIONERS
Dr. Priya Sen*, Dr Tan Hiok Hee **, A/Prof Roy Chan***
* Associate Consultant Dermatologist
** Consultant Dermatologist
*** Medical Director and Senior Consultant Dermatologist, National Skin Centre
Introduction
Congenital syphilis is a serious and life threatening infection in an infant. It is contracted from an infected mother via transplacental transmission of the Spirochaete Treponema pallidum at any time during pregnancy or at birth. It was initially believed that this infection is not transmitted across the placenta to the unborn infant until after the 4th month of pregnancy1 due to the protective effect of the cytotrophoblastic (Langhan’s) layer but later studies have showed that infection of the foetus can occur early even before the 10th week of pregnancy2. The lack of prenatal care and screening largely contributes to the incidence of congenital syphilis3.
Aetiology and pathogenesis
Congenital syphilis occurs when T. pallidum from the mother invades and crosses the placenta. The organism enters the bloodstream of the foetus and multiplies to large numbers with subsequent invasion of multiple organs including the liver, the skin, mucous membranes, bones as well as the central nervous system.
Clinical features
The severity of infection to the foetus is dependent on the stage of development at which the infection has taken place and the time that has elapsed before treatment. Congenital syphilis may produce intrauterine growth retardation, prematurity, and small for gestational age foetuses4. In infancy, failure to thrive, persistent rhinitis, an intractable diaper rash, unexplained jaundice, hepatosplenomegaly, or anaemia of uncertain cause should raise a suspicion of congenital syphilis.
The clinical presentation of congenital syphilis is divided into early (< 2 years of age) and late (> 2 years of age) disease. Early disease usually presents before 3 months of age but can occur anytime within the first 2 years.
Mucous membrane involvement is often the earliest sign and may present as snuffles (syphilitic rhinitis). This begins as a clear nasal discharge, teeming with Spirochaetes and is highly infectious, can be progressively more profuse and occasionally blood-tinged. Further inflammation and ulceration of the nasal mucosae can result in perforation of the nasal septum with a consequent "saddle nose" deformity. Condyloma lata are highly infectious flat-topped papules and plaques that occur at the mucocutaneous junctions of the nares, angles of themouth, and in the anogenital region. Chronic induration resulting in these areas predisposes to linear scars or rhagades, which commonly fan out from the corners of the mouth or the affected orifices. Mucous patches may appear on the lips, tongue and palate and are more common in infants with severe systemic disease5.
The most common cutaneous lesion is a maculopapular rash that is oval and pink or red, subsequently becoming coppery-brown associated with scaling particularly on the palms and soles. The lesions are more common on the posterior aspect of the body particularly the buttocks, back, thighs and soles. Other early cutaneous findings include petechiae (from thrombocytopaenia) and haemorrhagic vesicles and bullae (pemphigus syphiliticus).
The early extracutaneous findings in congenital syphilis include low birth weight, jaundice, hepatomegaly with elevation of serum alkaline phosphatase, splenomegaly, anaemia and thrombocytopaenia, generalised lymphadenopathy, osteochondritis, respiratory distress, hydrops fetalis, nephrotic syndrome, meningitis, chorioretinitis and pseudoparalysis6.
The late clinical features of congenital syphilis appear after 2 years of age. This involves the central nervous system (neurosyphilis, which may be asymptomatic), the teeth (Hutchinson peg-shaped notched central incisors, mulberry multicuspid first molars), bones (saddle nose, frontal bossing, concave central face, sabre shins, Clutton’s joints), skin (rhagades, nodular syphilides, gummata), eyes (interstitial keratitis, optic atrophy) and ears (CN VIII nerve deafness)7. Hutchinson’s triad consists of notched central incisors, interstitial keratitis and CN VIII nerve deafness - this is pathognomonic.
Diagnosis
Serological diagnosis is generally made by using nontreponemal antibody tests (VDRL, RPR) for screening in conjunction with specific treponemal antibody tests for confirmation (TPPA, FTA-Abs). Caution must be taken when interpreting results as maternal non-treponemal and treponemal IgG antibodies can be present in the foetus resulting from transplacental transfer even if the mother was adequately treated during pregnancy (Table 1). As a result, serum should be taken from the infant, as oppose to cord blood, in order to enhance the accuracy of serologic test results.
The diagnosis of congenital syphilis can also be made by the demonstration of Spirochaetes within a clinical specimen using dark field microscopy or direct fluorescent antibody testing. Radiographic abnormalities are particularly important since they are present in up to 95% of symptomatic and 20% of asymptomatic neonates with congenital syphilis8. A CSF examination should be performed to exclude neurosyphilis.
The following is a guide to the evaluation of a suspected case of early congenital syphilis9:
1. Maternal history, including results of serologic testing and treatment.
2. Physical examination of mother and neonate
3. Serological tests (RPR/TPPA/FTA-Abs)
4. CSF analysis (cell count, protein level determination, VDRL)
5. Dark field microscopy or DIF of clinical lesions or body fluids
6. Long bone radiographs (diaphyseal periostitis, osteochondritis, Wimberger’s sign - bilateral metaphyseal destruction in upper medial tibias)
7. Other tests as clinically indicated (FBC, LFTs, UFEME, CXR)
8. HIV antibody test
Treatment9
1. Intramuscular Aq. Procaine Penicillin G 50 000 units/kg/day daily x 10 days, or
2. Intravenous Aq. Crystalline Penicillin G 50 000 units/kg/day every 12 hours (total 100 000 to 150 000 units/kg/day) during the 1st 7 days of life, and every 8 hours thereafter for a total of 10 days, or
3. Intramuscular Benzathine Penicillin 50 000 units/kg daily x 10 days
In asymptomatic infants with negative investigations (apart from serology), the decision to treat or not should be made after consideration of the maternal history and the serology of the mother and baby.
Follow-up
Infants should be followed up at 1, 2, 4, 6 and 12 months of age. Serologic non-treponemal tests should be performed at 3, 6 and 12 months after the completion of treatment or until they become non-reactive. Nontreponemal antibody titres decline by 3 months of age and should be non-reactive by 6 months of age if the infant was not infected and the initially positive serologic test reflected transplacentally acquired maternal antibody. Patients with persistent, stable titres, including those with low titres should be considered for re-treatment.
Infants with congenital neurosyphilis and initial positive CSF VDRL or abnormal or uninterpretable CSF cell counts and/ or protein should undergo repeat clinical evaluation and CSF examination at 6 month intervals until their CSF examination is normal. A reactive CSF VDRL at 6 months of age is an indication for re-treatment.
Prevention
Congenital syphilis is an easily preventable infection. The prognosis in promptly treated early congenital syphilis is excellent. It is recommended that all pregnant women should have a serologic test for syphilis during the 1st trimester and a repeat test should be performed toward the end of pregnancy or at the time of delivery for women in high-risk groups. The cord blood should also be tested.
Risk behaviours and low socio-economic status have been found to constitute two separate maternal profiles associated with congenital syphilis10. Effective prevention strategies should target each maternal profile.
References
- Congenital syphilis. Department of Neonatal Protocol Book. Royal Prince Alfred Hospital.
- Clinical practice in sexually transmitted infections. Saunders 2002: pp395-456.
- Congenital syphilis New York City, 1986-1988. MMWR 1989; 38:835-829.
- Early congenital syphilis in the new millenium. Paed Derm Vol. 19 No. 3 May/June 2002. 5. Solomon L, Esterly N. Neonatal Dermatology. Philadelphia:WB Saunders, 1973: pp 158-162.
- Chawla V, Pandit P, Nkrumah F. Congenital syphilis in the newborn. Arch Dis Child 1988; 63:1393-1394.
- Textbook of Neonatal Dermatology. WB Saunders, 2001:pp 196-200.
- Brion L, Manuli M, Rai B et al. Longbone radiographic abnormalities as a sign of active congenital syphilis in asymptomatic newborns. Paediatrics 1991; 88:1037-1040.
- Sexually transmitted infections. Management Guidelines of the Department of STI Control (Singapore) 2003.
- Lago EG, Fiori RM, Stein AT. Congenital syphilis: identification of two distinct profiles of maternal characteristics associated with risk. Sex Trans Dis 2004; 31(1): 33-7.
- Lago EG, Fiori RM, Stein AT. Congenital syphilis: identification of two distinct profiles of maternal characteristics associated with risk. Sex Trans Dis 2004; 31(1): 33-7.
DEDICATED TO EXCELLENCE IN DERMATOLOGY
By National Skin Centre (Singapore)
Copyright (C) 1995 - National Skin Centre (Singapore)
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