Congenital syphilis is a potentially devastating infection that results from mother to child transmission (MTCT) of Treponema pallidum subspecies pallidum (T. pallidum), the etiological agent of syphilis, via the placenta during pregnancy.1 Mother to child transmission of syphilis can be prevented by universal screening for maternal syphilis early in pregnancy, preferably in the first trimester, and treatment of infected women and their sexual partners with intramuscular benzathine penicillin G (BPG), the recommended first-line drug for syphilis.1,2 In 2007, the World Health Organization (WHO) launched a global initiative to eliminate congenital syphilis.3 This strategy called for actions that are based on 4 “pillars,” namely: (1) ensuring sustained political commitment and advocacy; (2) increasing access to, and quality of, maternal and newborn health services; (3) screening and treating pregnant women and their sexual partners; and (4) establishing surveillance, monitoring and evaluation systems. Newman et al4 estimated that in 2008 approximately 1.4 million pregnant women had probable active syphilis that resulted in 521,000 adverse outcomes including 212,000 stillbirths or fetal deaths, 92,000 neonatal deaths, 65,000 pre-term or low birth weight infants, and 152,000 infants with congenital infection. The WHO estimated that in 2012 there were approximately 950,000 maternal syphilis infections that resulted in 360,000 adverse outcomes including 110,000 infants with congenital infection.5 The approximately 33% decline in maternal syphilis infections and adverse pregnancy outcomes from 2008 to 2012 showed that reducing MTCT of syphilis has a positive impact on maternal and child health.
In 2010, the Pan American Health Organization initiated a regional strategy for the Americas with the broader goal of the dual elimination of MTCT of syphilis and HIV through integration of the screening programs for both infections into routine antenatal care (ANC).6 This strategy, which was updated in 2015, aims to detect and treat syphilis and HIV in early pregnancy so that infants will be born free of these diseases.6,7 The use of rapid, dual point-of-care (POC) tests for the detection of antibodies to T. pallidum and HIV enables screening for both infections simultaneously with finger prick blood during the ANC visit.8 These simple, cost-effective tests can be performed even in low resource settings that lack access to traditional laboratories. As a result, treatment for syphilis and/or HIV can be initiated promptly, thereby reducing patient loss to follow-up. Although dual POC tests show considerable promise, most countries in the Americas region have yet to use the new tests. These countries continue to use traditional and/or reverse serological diagnostic algorithms for syphilis testing based on the combination of non-treponemal tests such as the Venereal Disease Research Laboratories/Rapid Plasma Reagin tests and treponemal tests such as the Treponema pallidum Hemagglutination Assay/Treponema pallidum Particle Assay.
Pan American Health Organization supports the dual elimination of MTCT of syphilis and HIV through the integration of services and surveillance in existing maternal and child health programs. Countries must achieve, for at least 1 year, the impact target of ≤50 cases of congenital syphilis per 100,000 live births and ≤30 cases of pediatric HIV per 100,000 live births, as well as a rate of ≤2% of MTCT of HIV in non-breastfeeding populations.7 Countries that seek to validate the elimination of MTCT of syphilis must provide evidence that process targets have been met by supplying at least two years of data that show that: (1) more than 95% of pregnant women attend at least one ANC visit, (2) more than 95% of pregnant women are screened for syphilis and HIV and know their test results, and (3) more than 95% of pregnant women who screen positive for syphilis and/or HIV are adequately treated. Additionally, these countries are expected to maintain effective program interventions and quality surveillance systems to monitor cases of MTCT of syphilis and HIV. As countries work to achieve elimination of MTCT of syphilis, the need for BPG is anticipated to increase with the expanded screening of pregnant women during ANC visits.9 In May 2016, the 69th World Health Assembly recognized BPG as an essential medicine that has been in short supply for several years. Stock outs of BPG have been reported across three WHO regions including the Americas. Ensuring a continuous global supply of BPG is critical because BPG is the only recommended treatment for pregnant women and infants with syphilis. World Health Organization is collaborating with international partners to assess the global supply, current and projected national needs, and production capacity for BPG.
In 2014, 17 countries in the Americas region, including the United States, reported data compatible with meeting the targets for the dual elimination of MTCT of syphilis and HIV.7 Cuba is the first country in the world and, as of August 2016, the only country in the Americas that has received official validation from the WHO of the dual elimination of MTCT of syphilis and HIV.10 Cuba's success, despite its modest economic resources, is attributable to its strong primary health care infrastructure, synergized data information systems, and core of well-trained doctors and nurses who provide basic health services that are accessible and free of charge to all.
Although progress is being made in the elimination of congenital syphilis, control of syphilis in the natural reservoir of infection (ie, untreated or inadequately treated sexually active adults) remains problematic. Adult syphilis is endemic in several low-income countries in the Americas and rates have increased markedly in high-income countries such as the United States and Canada.11,12 Infectious (ie, primary and secondary stage) syphilis is disproportionately common among men, particularly men who have sex with men (MSM), in part because partner change tends to be high and condom use low. MSM who have sex with women (MSMW) have similar or, in some cases, a greater likelihood of infection with syphilis compared to MSM-only.13 MSMW who engage in unprotected sex may spread syphilis from their high-risk male partners to their low-risk female partners who are pregnant or may become pregnant. The possibility of bisexual bridging of sexually transmitted infections highlights the need for all pregnant women to be screened for syphilis during early pregnancy.1 Moreover, pregnant women who are at increased risk for syphilis or living in areas where syphilis prevalence is high should be screened for syphilis at their first trimester ANC visit, at the beginning of their third trimester, and at delivery.1,2 Those who are infected must be treated with BPG and monitored for an appropriate clinical and serological response to prevent MTCT of syphilis. Additionally, the sexual partners of pregnant women with syphilis should be treated with BPG or an appropriate alternative drug if BPG is unavailable and monitored to ensure that re-infection of the pregnant woman does not occur. Any neonate at risk for congenital syphilis must receive a full evaluation, be screened for syphilis, and treated appropriately.2
Although, the elimination of MTCT of syphilis is not an easy goal, Cuba (June 2015) and Thailand, Belarus and the Republic of Moldova (June 2016) have shown that it is an attainable one.10,14 Several countries in the Americas are poised to eliminate MTCT of syphilis.7 Nonetheless, syphilis continues to cause adverse pregnancy outcomes, even in women who receive ANC, in some other countries in this region. Improving access to quality ANC, including POC testing with prompt, effective treatment and counseling of pregnant women and their sexual partners, and establishing robust systems for surveillance, monitoring and evaluation are key to the elimination of MTCT of syphilis. Because of the widespread Zika virus epidemic, low-income countries in the Americas region are facing unanticipated challenges to their maternal and child health services that could hinder efforts to eliminate MTCT of syphilis.15,16 It is imperative that the commitment of these countries to the elimination of MTCT of syphilis be strengthened and sustained to ensure that this goal, which is almost within reach, does not slip away.
1. Braccio S, Sharland M, Ladhani SN. Prevention and treatment of mother-to-child transmission of syphilis. Curr Opin Infect Dis 2016; 29:268–74.
2. Workowski KA, Bolan GA, Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recommend Rep 2015; 64(RR-03):1–137.
4. Newman L, Kamb M, Hawkes S, et al. Global estimates of syphilis in pregnancy and associated adverse outcomes: Analysis of multinational antenatal surveillance data. PLoS Med 2013; 10:e1001396.
6. Pan American Health Organization. Strategy and plan of action for the elimination of mother-to-child transmission of HIV and congenital syphilis in the Americas. 50th Directing Council, 62nd Session of the Regional Committee. Resolution CD50.R12. PAHO, Washington, DC, 2010. http://new.paho.org/hq/dmdocuments/2010/CD50.R12-e.pdf
8. Bristow CC, Leon SR, Huang E, et al. Field evaluation of a dual rapid immunodiagnostic test for HIV and syphilis infection in Peru. Sex Transm Dis 2016; 43:57–60.
9. Taylor MM, Nurse-Findlay S, Zhang X, et al. Estimating benzathine penicillin need for the treatment of pregnant women diagnosed with syphilis during antenatal care in high-morbidity countries. PLoS One 2016; 11:e0159483.
10. Kamb ML, Caffe S, Perez F, et al. Cuba eliminates mother-to-child transmission of HIV and congenital syphilis: A call to action for the America region. J bras Doencas Sex Transm 2015; 27:3–5.
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13. Jeffries WL 4th. Beyond the bisexual bridge: Sexual health among U.S. men who have sex with men and women. Am J Prev Med 2014; 47:320–9.
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