November 12, 2015
3 min read

Congenital syphilis rates increase across US

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The incidence of congenital syphilis in the United States increased 38% between 2012 and 2014, with last year’s overall case rate the highest recorded since 2001, according to recently published CDC surveillance data.

This increase mirrors — and may be driven by — similar increases in syphilis infection rates among women over this same time period, according to Virginia Bowen, PhD, MHS, officer of the CDC’s Epidemic Intelligence Service, and colleagues.

Virginia Bowen

“The findings from this report show we are missing opportunities to screen and treat pregnant women for STDs,” Bowen told Infectious Disease News. “Syphilis in pregnant women can cause miscarriages, premature births, stillbirths, or death of newborn babies. We have great tests and effective treatment for syphilis — there’s no excuse for allowing it to resurge, especially among pregnant women who are largely engaged in medical care.”

A reversal of positive trends 

Previous surveillance data showed a decrease in congenital syphilis cases from 1991 to 2005, but more recently a minor increase from 2005 to 2008. To document more recent incidence rates and identify transmission trends, Bowen and colleagues examined CDC surveillance data collected through the National Notifiable Diseases Surveillance System from 2008 to 2014. Included cases of congenital syphilis included stillbirths, infants with clinical evidence of the disease, and all stillbirths and infants born to mothers with undertreated syphilis. Incidence rates were calculated per 100,000 live births as determined by data from the National Center for Health Statistics. Rates of primary and secondary (P&S) syphilis per 100,000 women obtained using U.S. Census population estimates also were collected for analysis, and demographic and clinical features of the infants and mothers were analyzed to identify trends in transmission.

From 2008 to 2012, the researchers observed a decline in congenital syphilis cases from 10.5 cases per 100,000 live births to 8.4 cases per 100,000 live births. This decline was seen within all regions of the U.S. except the Midwest, which reported a rate increase of 62%. Case rate decreases during this period were greater among whites than blacks, and the majority (57%) of congenital syphilis cases in 2012 were among infants with black mothers.

These overall positive trends were reversed from 2012 to 2014, as the congenital syphilis rate increased to 11.6 cases per 100,000 live births. This change was seen throughout the U.S., but was greatest in the West (5.5 cases per 100,000 live births vs. 12.8 cases per 100,000 live births). Incidence increases were seen among whites (61%), Hispanics (39%) and blacks (19%), although infants of black mothers remained the most affected in 2014.

There was a slight rise in the proportion of congenital syphilis cases that resulted in stillbirth or early infant death throughout the study period. Stillbirths accounted 5.4% of reported cases in 2008 and 5.5% in 2014, while reports of infant deaths within 30 days increased from 0.7% to 1.7% during the same time period. In 2014, 6.5% of reported cases had one or more clinical signs or symptoms of congenital syphilis infection, 11.4% other nonclinical evidence and 9.8% of cases had no treatment recorded at the time of reporting.

The importance of prenatal care

The trends in congenital syphilis identified by the researchers mirrored similar fluctuations observed among U.S. women. From 2008 to 2012, P&S syphilis decreased from 1.5 cases per 100,000 women to 0.9 cases per 100,000, and increased to 1.1 cases per 100,000 in 2014.

According to the researchers, the increase from 2012 to 2014 represents a “missed opportunity” to interrupt the transmission of the infection and is accompanied by low engagement with various areas of prenatal care.

“Notable increases of P&S syphilis among women can create a higher likelihood of increases in congenital syphilis,” Bowen said. “Prenatal care is essential to the overall health and wellness of mother and child — and late or inadequate care is a leading cause of congenital syphilis.”

The researchers found that more than one-fifth of mothers whose children were infected with congenital syphilis in 2014 received no prenatal care, and no information about care was available for 9.6%. Among those who attended one or more prenatal visits, 43% received no treatment for their syphilis infection throughout the pregnancy, and 30% received inadequate treatment. Further, 21 of the mothers who received prenatal care were never tested for syphilis, and 52 mothers acquired the infection after a negative screening early in the course of their pregnancy.

“A substantial percentage of [congenital syphilis] cases are attributable to a lack of prenatal care; even among those receiving some prenatal care, the detection and treatment of maternal syphilis often occurs too late to prevent [congenital syphilis],” they wrote. “Health departments, in partnership with prenatal care providers and other local organizations, should work together to address barriers to obtaining early and adequate prenatal care for the majority of vulnerable pregnant women.”

Along with improving testing and access to care among women of reproductive age and men who have sex with women, other areas of congenital syphilis prevention in need of increased attention include timely administration of antibiotic treatment, provision of STD partner services and accurate reporting of identified cases, the researchers concluded. – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.