Mystery Rash Leads to Diagnosis of Congenital Syphilis

By Oluwatosin Goje, MD

Congenital syphilis is a rare, disabling condition spread through the placenta from an infected mother to her infant. A diagnosis of syphilis in pregnancy is always treated as soon as possible. With successful maternal treatment, infants tend to have positive outcomes.

Caused by Treponema pallidum, the condition can be life-threatening infection in infants. Many babies with congenital syphilis are stillborn. Others may be asymptomatic at birth and develop symptoms over time, such as an enlarged liver, failure to thrive, irritation of skin around mouth, genitals and anus, rash on palms and soles, skeletal abnormalities and watery discharge from nose. Untreated infants can develop blindness, deafness, facial deformities and nervous system problems.

Mystery rash leads to diagnosis

A young woman, pregnant with her first child, had a negative result on the initial rapid plasma regain (RPR) at 16 weeks. She delivered at term via cesarean section due to an active herpes infection. The post-partum course was uneventful, and both mother and baby were discharged home on postoperative day three, with pediatric follow-up on day 11 of baby’s life.

At 4 weeks, mom brought baby to see pediatrician for a rash on arms and throat, which she had treated at home with bacitracin. The infant showed no other obvious symptoms at the time. Mother and newborn had a few more follow-up visits with the pediatrician to monitor the improvement and/or resolution of the rash, which was also noted in the diaper area. Because the mother had tested negative for syphilis when tested prenatally, congenital syphilis was not considered as a contributing factor to the rash.

Both the young mother and the pediatric team continued to seek answers. At age 3 months, a pediatric dermatologist was consulted about the persistent rash and more laboratory testing, including RPR testing of mother and newborn, was requested. This baby was diagnosed with congenital syphilis.

Baby was admitted and started on a 10-day course of intravenous penicillin. Additional studies indicated that the infant’s organs, sight and hearing were unaffected. He had perianal condyloma lata, which fully resolved by 6 months of age, a saddle nose deformity, his cerebrospinal fluid screen was positive for syphilis with high titers. The infant was stable following antibiotic treatment.

Congenital syphilis case despite standard prenatal care

This is an unusual case with important teaching/learning points because the mother received high-quality, standard-of-care prenatal services, and was negative for syphilis when tested early in her pregnancy. As part of the standard of care, all pregnant women receive the syphilis IgG screen or rapid plasma reagin (RPR) test for syphilis at the first prenatal visit. Pregnant women who test positive are further investigated; they receive serial obstetric ultrasounds looking for evidence of congenital syphilis, and then are treated with a series of Benzathine penicillin G injections based on diagnosis. Treatment effectively clears the infection. The mother was infected during pregnancy, but after the RPR at 16 weeks’ gestation. It is recommended that women considered at high-risk for contracting syphilis during pregnancy be given a second syphilis test at 28-32 weeks of pregnancy. In this case, however, the mother was not considered high risk and no second syphilis or RPR test ordered.

As an institute, we went back to the drawing board to further investigate the problem and seek opportunities for process improvement. Unless a woman is at high-risk for sexually transmitted infections, we screen for syphilis only once, in the first trimester of pregnancy. Traditionally, populations considered at high-risk include men who have sex with men, and men and women who are HIV positive. Additional risk factors include incarceration, working in the sex trade and belonging to certain racial groups with historically higher incidence rates.

More recent CDC recommendations indicate a second RPR/syphilis test in the third trimester for pregnant women living in high-incidence regions, regardless of the outcome of the first test. In 2017, syphilis rates in the United States increased 10.5% from 2016 to 9.5 cases per 100,000 population. Although Ohio comes in below the 2017 national average at 7.2 cases per 100,000 population, urban areas such as Franklin and Cuyahoga county have rates of 25.4 and 12.6 per 100,000.

Realizing that we are in a high-incidence region for syphilis, many women in our care meet the criteria for a second syphilis screen. Our hope is that, by recommending a universal second RPR/syphilis test at 28-32 weeks, maternal syphilis contracted during pregnancy would be appropriately diagnosed and treated with an antibiotic regimen at least 30 days prior to delivery..

Although this is an unfortunate case, we applaud this mother and her caregiving team for continuing to question the infant’s symptoms until a diagnosis could be made. This truly was a team effort.