CASE Pregnant woman with positive Treponema pallidum antibody test
A 30-year-old primigravida at 10 weeks and 4 days of gestation by her last menstrual period presents to your office for her initial prenatal visit. She expresses no concerns. You order the standard set of laboratory tests, including a sexually transmitted infection (STI) screening panel. Consistent with your institution’s use of the reverse algorithm for syphilis screening, you obtain a Treponema pallidum antibody test, which reflexes to the rapid plasma reagin (RPR) test. Three days later, you receive a notification that this patient’s T pallidum antibody result was positive, followed by negative RPR test results. The follow-up T pallidum particle agglutination (TP-PA) test also was negative. Given these findings, you consider:
- What is the correct interpretation of the patient’s sequence of test results?
- Is she infected, and does she require treatment?
Meet our perpetrator
Syphilis has plagued society since the late 15th century, although its causative agent, the spirochete T pallidum, was not recognized until 1905.1,2T pallidum bacteria are transmitted via sexual contact, as well as through vertical transmission during pregnancy or delivery. Infection with syphilis is reported in 50% to 60% of sexual partners after a single exposure to an infected individual with early syphilis, and the mean incubation period is 21 days.3T pallidum can cross the placenta and infect a fetus as early as the sixth week of gestation.3 Congenital syphilis infections occur in the neonates of 50% to 80% of women with untreated primary, secondary, or early latent syphilis infections; maternal syphilis is associated with a 21% increased risk of stillbirth, a 6% increased risk of preterm delivery, and a 9% increased risk of neonatal death.4,5 Additionally, syphilis infection is associated with a high risk of HIV infection, as well as coinfection with other STIs.1
Given the highly infective nature of T pallidum, as well as the severity of the potential consequences of infection for both mothers and babies, primary prevention, education of at-risk populations, and early recognition of clinical features of syphilis infection are of utmost importance in preventing morbidity and mortality. In this article, we review the epidemiology and extensive clinical manifestations of syphilis, as well as current screening recommendations and treatment for pregnant women.
The extent of the problem today
Although US rates of syphilis have ebbed and flowed for the past several decades, the current incidence has grown exponentially in recent years, with the number of cases reported to the Centers for Disease Control and Prevention (CDC) increasing by 71% from 2014 to 2018.6 During this time period, reported cases of primary and secondary syphilis in women more than doubled (172.7% and 165.4%, respectively) according to CDC data, accompanied by a parallel rise in reported cases of congenital syphilis in both live and stillborn infants.6 In 2018, the CDC reported a national rate of congenital syphilis of 33.1 cases per 100,000 live births, a 39.7% rise compared with data from 2017.6
Those most at risk. Risk factors for syphilis infection include age younger than 30 years, low socioeconomic status, substance abuse, HIV infection, concurrent STIs, and high-risk sexual activity (sex with multiple high-risk partners).3 Additionally, reported rates of primary and secondary syphilis infections, as well as congenital syphilis infections, are more elevated among women who identify as Black, American Indian/Alaska Native, and/or Hispanic.6 Congenital infections in the United States are correlated with a lack of prenatal care, which has been similarly linked with racial and socioeconomic disparities, as well as with untreated mental health and substance use disorders and recent immigration to the United States.5,7
Continue to: The many phases of syphilis...