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Nonvenereal Transmission of Syphilis in Infancy by Mouth-to-Mouth Transfer of Prechewed Food

Zhou, Pingyu MD, PhD; Qian, Yihong MD; Lu, Haikong MD; Guan, Zhifang MD

Sexually Transmitted Diseases: April 2009 - Volume 36 - Issue 4 - p 216-217
doi: 10.1097/OLQ.0b013e3181901c79

Early recognition of acquired syphilis in childhood is vital. Children may acquire syphilis as a consequence of kissing, breast-feeding, or handling. We report 2 cases of infantile syphilis transmitted by mouth-to-mouth feeding from actively infected relatives. Syphilis should be suspected in children presenting with atypical rashes accompanied by headache, sore throat, and adenitis, especially if family members are affected by active syphilis.

From the Department of STD Institute, Shanghai Skin Disease and STD Hospital, Shanghai, China

The authors thank Kefei Kang and Dr. Shun Lv for their helpful comments in writing this article.

Correspondence: Pingyu Zhou, MD, PhD, Department of STD Institute, Shanghai Skin Disease and STD Hospital, 196 Wuyi Road, Shanghai, China, 200050. Email:

Received for publication May 3, 2008, and accepted October 3, 2008.

SYPHILIS IS PRIMARILY A SEXUALLY TRANSMITTED INFECTION and is caused by Treponema pallidum. It is estimated that 30% to 60% of sexual contacts of individuals with early syphilis will acquire syphilis themselves.1,2 Children may be infected either in utero (congenital syphilis) or in ways similar to adults (acquired syphilis). The presence of a sexually transmissible disease in a child after the neonatal period is suggestive of sexual abuse.3,4 However, children may also acquire syphilis during early childhood as a consequence of kissing, breast-feeding, handling, or prechewed food feeding.5,6

Prechewing infants’ food is a common behavior in some countries, especially in developing countries. In Bali, for example, infants are fed prechewed food mixture of rice and banana,7 and in Zaire, infants are given prechewed food as early as their second or third week of life.8 Even in developed countries, such as the United States, some specialists think that prechewing of babies’ food might be more common than generally considered.9 That the behavior of prechewing infants’ food by their caregivers could be a way of disease transmission is not fully recognized in China. Prechewing food is a custom in most parts of China; however, no studies have been conducted yet to evaluate prechewed food as one of the important disease transmission routes. It has been reported that prechewing is associated with spread of other infections, including Streptococcus in the United States.9 More recently, prechewed food feeding has been believed to be a way of transmission of human immunodeficiency virus (HIV).10 We hereby report 2 cases of infantile syphilis acquired by prechewing feeding.

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An 18-month-old male infant presented with “thrush” for 2 weeks, which was said to be improving with methylrosanilinium chloride treatment. However, he was referred to us for further evaluation because his grandparents, who care for him, had been diagnosed with secondary syphilis 2 days ago in our hospital, and his grandmother was known to have oral mucous patches and papules. On examination, the boy had mucous patches over the tongue, palate, and cheeks, and a generalized lymphadenopathy with markedly swollen glands of the right neck. There was no other rash or anogenital lesion, and scalp and hair were normal. Serology showed positive rapid plasma reagin (RPR) (1:64), positive T. pallidum particle agglutination assay (TPPA) (>1:80), and negative HIV. The boy was given procaine penicillin 5 million IU/kg/day for 15 days. The mucous patches in his mouth disappeared within 3 days.

His father and mother had no signs or symptoms of syphilis. Routine prenatal RPR, and HIV tests of the mother had been negative, and examination and serology, including RPR, HIV, and TPPA were again negative. On further inquiry, the grandfather admitted to have had extramarital unprotected intercourse 4 months ago, while continuing to have intercourse with his wife. He had had a painless sore on his penis 3 months before a rash appeared on his trunk and limbs. The grandmother was in the habit of prechewing food before feeding it to the child, even when her mouth was affected by the mucous patches and papules.

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A 10-month-old female infant presented with a red throat and lymphadenopathy behind her right ear, without generalized lymphadenopathy. Her mother had been diagnosed with secondary syphilis 2 days ago. There were neither mucous lesions in the child’s mouth nor other rash and anogenital lesions, and hair and scalp were normal. Serology showed positive RPR (1:4), positive TPPA (>1:80), and negative HIV test result.

The child’s father had no signs of syphilis, but serology showed positive RPR (1:32), positive TPPA (>1:80), and negative HIV. He mentioned that three and half months ago he had a sore throat, headache, high fever, followed by a generalized rash, thought to be influenza and a drug erythema. Both parents denied a history of syphilis before their marriage 2 years ago and their premarriage health check was normal. The father refused to answer questions about his sexual behavior, while his wife was pregnant.

The mother denied syphilis during pregnancy and RPR and HIV tests in the first trimester and at the end of pregnancy were all negative. She had not had intercourse during pregnancy until the child was 3 months old. Two months ago she had a severe sore throat. Acute pharyngitis was diagnosed and treated with traditional Chinese medicine. Then she visited our hospital with oral mucosal patches and lingual papules (Fig. 1). Demonstration of T. pallidum in smears from the tongue papules, together with positive RPR and TPPA, confirmed secondary syphilis. After procaine penicillin treatment for 15 days, the lingual papules disappeared.

Figure 1.

Figure 1.

The child was not breast-fed, but the mother was in the habit of chewing food before giving it to her. The child was diagnosed as having acquired early latent syphilis and was given procaine penicillin 5 million IU/kg/day, for 15 days. After 3 months, RPR of the child was positive/negative and that of the parents was negative.

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The occurrence of acquired syphilis in early childhood is highly suggestive of sexual abuse transmission, but other modes of transmission exist. Nonvenereal transmission to young children was thought to be relatively common in the prepenicillin era3,11,12; some studies then suggested a rate of about 23% of nonsexual transmission in children.3,13 Murrell et al. (1947)14 reported 6 cases of syphilis in children, acquired through close contact with an actively infectious individual. In his classic text “Modern Clinical Syphilology,” Stokes comments that caregivers are sources of “too many such tragic situations,”15 but this knowledge has almost totally been neglected during “the illusory eradication of syphilis by penicillin.”16 We report these 2 cases of the disease transmitted via prechewed food feeding to again draw attention to the potential for syphilis patients caring for children in transmitting T. pallidum.

Although prechewing food for a child is a rare cause of transmission, it was recognized by Hofmann in 1998.6 Syphilis transmitted via this route may be underestimated in China because most caregivers were not asked whether they prechewed their infants’ food. When the question was asked, most people in our clinic reported that they occasionally prechewed the food and fed it to their babies when baby food was unavailable or as a means of pulverizing food for toothless infants. This behavior is most commonly seen among people from rural areas, or who are poorly educated, and there is no ethnic difference. To prevent this type of infection, it is important that caregivers are educated about the unhealthy nature of this custom.

The manifestations of acquired syphilis in children may mimic other diseases such as rubella, thrush, scabies with impetigo, pityriasis rosea, drug erythema, viral exanthema, streptococcal tonsillitis, and influenza. Malaise and anorexia are early symptoms followed by rash and sore throat with adenitis. Condylomata in the genital or anal regions appear later. In cases of oral transmission, the first symptoms are in the mouth or tonsils, and as in the first case, associated cervical adenopathy may be marked. To aid diagnosis, a detailed history and intensive physical examination are needed. A full family history should be obtained, with particular reference to whether the parents or other caregivers have ever been treated for syphilis. Samples should be taken from moist lesions to look for T. Pallidum as well as serology for RPR and TPPA.

Almost all children with syphilis acquire it from adults, so the epidemiology of adult syphilis is important in understanding its occurrence in children. In the late 1990s, syphilis reemerged as an important contagious infection in China. In 2007, 225,601 cases of syphilis were reported, including 117,986 cases with highly contagious early syphilis.17 Physicians should be aware that the risk of syphilis in early childhood is similarly increased.

Our cases suggest that prechewing infants’ food may be a way of syphilis transmission. Further studies would be required to determine the prevalence of the prechewing infants’ food practice in all parts of China and to validate whether this behavior is one of the important syphilis transmission routes.

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