Pediatric patients may acquire syphilis through nonsexual transmission as a result of close and repetitive contact with lesions of individuals with active syphilis. We chronologically describe the evaluation of a family cluster in which several members acquired syphilis without evidence of sexual transmission. Clinical evaluation and psychosocial assessment of the index case, sibling, and family group showed no evidence of sexual abuse. The children's mother, who had negative serologic tests for syphilis during hospitalization, developed clinical signs of secondary syphilis 48 days after the diagnosis of the index case, with seroconversion in both treponemal and nontreponemal tests. We emphasize that in any minor diagnosed with syphilis, sexual abuse must always be ruled out. If no family behaviors suggest such a route, alternative modes of transmission should be considered.
Syphilis is primarily transmitted through sexual contact or congenitally; however, nonsexual transmission may occur through close contact with family members or caregivers with active syphilis who have skin and/or mucosal lesions.1–3 Consistent with the increasing prevalence of the disease in our country and among young women, cases of nonsexual transmission in children have been reported.4,5
Mucocutaneous lesions of secondary syphilis contain a high burden of Treponema pallidum (TPA).6 Condyloma lata, a typical secondary lesion, is usually located in moist friction areas such as the perianal region. These lesions contain a high number of treponemes and are therefore highly contagious upon contact.4,7,8 Close and repetitive contact through skin and mucosal lesions has been described as a source of infection.9–12
To ensure protection of the minor, all cases of acquired syphilis require exclusion of sexual abuse.4 Evaluation must be rigorous, as incorrect attribution to sexual transmission may lead to unnecessary hospitalization and legal consequences, as well as stigmatization of family members. We describe the chronological diagnosis of syphilis in several members of a family group in whom no evidence of sexual transmission was found.
Patient #1: index caseA 2-year-old boy was evaluated after his mother noticed perianal lesions during hygiene. The family lived in a low-income neighborhood but had access to water and electricity. Perianal and penile condyloma lata were observed, along with a nonpruritic erythematous micropapular rash on the palms (Fig. 1). Given suspicion of syphilis, hospitalization was indicated to rule out possible sexual transmission. The nontreponemal test (RPR) was positive at 32 dilutions, and the treponemal test (TPHA) was positive at 1/10240 (reference value <1/80). Serologies for HIV, HBV, HCV, and herpes virus were negative. Maternal serologies during pregnancy were negative, ruling out congenital transmission. As sexual transmission had not yet been excluded at diagnosis, IV penicillin G (50000IU/kg/day) was administered for 10 days. RPR became negative 18 months into therapy, with a sustained decline in TPHA titers. Urinalysis, complete blood count, long bone radiography, abdominal ultrasound, and fundus examination were normal. Psychological evaluation was conducted through play sessions in different contexts (with peers, alone, with the mother, and during hospitalization), with additional observation by the psychopathology team. No indicators suggestive of sexual abuse were identified.
(A) Condyloma lata in the perianal region of patient #1 (index case). (B) Nonpruritic erythematous micropapular rash on the palms of patient #1 (index case). (C) Lesion in the mother (patient 4), consisting of a nonpruritic erythematous micropapular rash on the trunk corresponding to secondary syphilis.
The family underwent detailed history-taking and physical examination for signs of syphilis and possible abuse. Serologic testing of the mother, father, maternal grandparents, maternal uncle, maternal aunt, and a 5-year-old cousin was negative. The 3.5-year-old brother tested positive (patient #2) and was hospitalized for treatment. Both parents worked most of the day, leaving the children under the care of an 18-year-old caregiver (patient 3), who tested positive for RPR/TPHA. The chronology of family evaluation is shown in Fig. 2.
Chronology of serologic evaluation of the family group. The graph illustrates the timing of serologic testing in all family members and the caregiver, using day 0 as the diagnosis of the index case (patient #1). Onset of maternal clinical signs and subsequent seroconversion are shown, consistent with nonsexual transmission through close contact with her children.
Sibling of the index case. A 3.5-year-old boy with positive RPR (4 dilutions) and TPHA (1/5120). Physical examination was normal, and serologies for HIV, HBV, HCV, and herpes virus tested negative. He received IV penicillin G (50000IU/kg/day) for 10 days due to delayed availability of maternal pregnancy serology. RPR and TPHA showed sustained decline after treatment. Laboratory tests, long bone radiography, abdominal ultrasound, and fundus examination were normal. Urinalysis revealed hematuria and proteinuria in the nephritic range, with normal creatinine and urea levels, leading to a diagnosis of membranous glomerulonephritis secondary to syphilis. Proteinuria persisted for 6 years before resolution.
Patient #3Caregiver. Examination revealed a painless infiltrated erosion with a reddish base on the right lateral border of the tongue, suggestive of secondary syphilis. Although the duration of the lesion could not be determined, it was the only active lesion identified in the family, suggesting it as the source of transmission. The caregiver reported placing the pacifier in her mouth before giving it to the children, tasting food before feeding them, and sharing utensils. RPR was positive at 32 dilutions and TPHA at 1/20240. She received 3 doses of benzathine penicillin G (2400000IU). Her partner also tested positive and received the same treatment. He had never visited or met the children, excluding suspicion of sexual abuse.
Patient #4Mother of the index case. She had negative serologies during both pregnancies and reported no additional sexual partners. During hospitalization, both RPR and TPHA tested negative, possibly corresponding to a serologic window period. After discharge, she developed a nonpruritic erythematous micropapular rash on the trunk (Fig. 1). RPR was positive at 32 dilutions and TPHA at 1/320. She received a single dose of benzathine penicillin G (2400000 IU), with serologic negativization within 1 year.
None of the patients presented traumatic genital lesions suggestive of sexual abuse or primary syphilis lesions. No indicators of sexual abuse were identified in the children at the 12-year follow-up.
DiscussionThe mechanism of tissue invasion by TPA is not fully understood. Most available data derive from animal models, and in vitro studies have demonstrated its ability to adhere to human endothelium and penetrate intercellular junctions, even in intact endothelium.12–14
In any child with syphilis, sexual abuse must be excluded. When this route is ruled out through multidisciplinary assessment, alternative transmission pathways should be considered.
In the pre-penicillin era, nonsexual transmission in children was considered relatively common.9
In both children, infection was most likely acquired through indirect nonsexual contact with the caregiver's oral lesion. This conclusion was reached through multidisciplinary evaluation, absence of psychosocial indicators of abuse according to current clinical practice guidelines,15 lack of blood transfusion history, and negative maternal serology during pregnancy. Absence of primary syphilis lesions (chancre) does not exclude sexual abuse, as these lesions may go unnoticed. However, our patients had no genital or anal lesions suggestive of abuse. Repeated psychosocial evaluation during hospitalization and long-term follow-up confirmed absence of abuse indicators.
Crowding, sharing beds, linens, towels, utensils, and toothbrushes may facilitate transmission when a household member has active secondary lesions.3,4,9,11,16 Our group previously studied 5 families with intrafamilial nonsexual transmission of syphilis, in which TPA strains matched between index cases and caregivers, with predominance of oral and exposed lesions.17 An infected caregiver may pose a risk to infants through practices such as moistening pacifiers with saliva or tasting food before feeding. Transmission through prechewed food has also been reported.3,8,9,11 In this family, both children were presumed to have been infected via repeated exposure to the caregiver's oral lesions. Subsequent maternal infection, along with consistently negative paternal serologies, supports nonsexual transmission through close contact, likely during hygiene care. Condyloma lata, due to its rare anogenital location, often leads to suspicion of sexual transmission, although this is not always the case.4,7,18
Determining the route of infection in syphilis is complex. Pediatric cases require hospitalization and multidisciplinary evaluation to exclude sexual abuse. In this family, after thorough assessment, transmission was attributed to contact with skin and mucosal lesions during routine caregiving practices.
This report highlights the possibility of nonsexual human-to-human transmission of acquired syphilis in pediatric populations.
Conflict of interestThe authors declare no conflict of interests.
