Syphilis is a sexually transmitted infection caused by the corkscrew-shaped spirochete bacterium Treponema pallidum that you are possibly familiar with. Millions of cases occur across the globe each year, predominantly in lower resource regions, but we are far from immune here in the United States. The CDC first began collecting data on syphilis in 1941 and cases began to decline dramatically after the introduction of penicillin and dedicated public health campaigns in the late 1940s. This decline persisted until the 1980s when cases spiked, largely in heterosexual men and women, during the crack cocaine epidemic. Once again, a dedicated public health effort bolstered by the general public’s growing focus on HIV prevention was successful, and cases plummeted.
There was a steady decline in cases of primary and secondary syphilis, which is when a person can most easily spread the disease to others, starting in 1990. We experienced what would be a nadir in syphilis incidence in the United States in 2000, with just under 6,000 total cases or 2.1 for every 100,000 Americans. This was the lowest rate since tracking of cases began.
Syphilis was fairly concentrated in the South and a few urban centers at that point. In fact, half of all new cases were diagnosed in only 21 counties and the city of Baltimore, which had a bit of a problem back then. 2,520 counties, which is about 80% of the total, reported zero primary or secondary cases of syphilis in 2000. The CDC got excited, and George W. Counts, MD, director of CDC’s syphilis elimination program, released a call to action:
“We have a brief window of opportunity to eliminate syphilis,” said Counts. “We must work together to rid our communities of this scourge. We cannot let this chance slip from our grasp.”
Alas, it wasn’t meant to be.
Cases of syphilis crept up slightly in 2001 and a trend of steady yearly increases in new infections has continued ever since. In 2019, the most recent year with complete and official data, almost 39,000 cases of primary and secondary syphilis were reported to the CDC. Since case counts began to increase in 2001, the majority of cases have been diagnosed in men, in particular men who have sex with men. Over the past few years, however, cases in men who have sex with men have leveled off at around 55-60% of total male cases, and significant increases are occurring in heterosexual men and women. Rates of syphilis have also increased across the United States and are no longer relegated to the South and a few large cities in other regions.
Not surprisingly, as cases of syphilis have increased in women there has been an increase in the incidence of babies infected during pregnancy. After a few years of stability, 2013 saw an increase in congenital syphilis with 9.2 cases for every 100,000 live births. Every year since 2012 has been worse than the year before. In 2019, there were 1,870 cases reported or 48.5 per 100,000 live births, which was about 40% more than in 2018, and an increase of about 400% from 2012. Not only are cases increasing in number, but they are more distributed across the country, with 43 states and the District of Columbia reporting at least once case of congenital syphilis in 2019.
A brief primer on congenital syphilis
Congenital syphilis typically occurs when a fetus becomes infected with the T. pallidum bacteria after it is transmitted across the placenta. Though uncommon, a newborn can also become infected during delivery when exposed to bacteria shed from infectious skin lesions. Transmission can occur at any point during pregnancy, though risk is increased if the mother is infectious earlier in pregnancy. Congenital infection is most likely to happen when mom has primary or secondary syphilis, with a 60-90% overall chance. The risk to the baby is low, around 2%, if at least 4 years have passed since mother became infected.
More than a million cases of congenital syphilis are estimated to occur around the world each year. Though the number of cases diagnosed in the United States make up a small percentage, it is still a major public health concern, particularly as rates have been steadily increasing. The reason most congenital syphilis happens in the United States is ultimately the same as why it might happen anywhere else. Whenever there is system with disparity in care, with large numbers of people having poor access to appropriate prenatal care or receiving inadequate management even when syphilis is diagnosed, it’s going to be a problem.
And it is a problem.
When a fetus is infected, the bacteria that cause syphilis have access to numerous organs via the bloodstream. This can cause an intense inflammatory reaction and severe damage, most commonly involving the bones, liver, pancreas, intestines, kidneys, and spleen, but other organs are also at risk. 40% of these pregnancies will end with a spontaneous abortion if mother has primary or secondary syphilis.
Most live born babies with syphilis will not have obvious problems, particularly if the baby was infected late in pregnancy or if the mother received partial but inadequate treatment. If an asymptomatic case is missed, and therefore goes untreated (penicillin), most of these babies will develop obvious disease by a few weeks of age. This can involve liver disease, characteristic rashes, swollen glands, bone defects, and syphilitic rhinitis, more commonly referred to as “snuffles“. It’s not as cute as it sounds.
Although less common, early congenital syphilis can present with a wide array of other abnormal findings, of which I’ll just name a few. Pseudoparalysis of Parrot is the name for when a baby with syphilis is unable to move an extremity because of severe pain caused by injury to a bone. Babies can also develop pneumonia, inflammation of the heart muscle or deeps structures of the eye, or severe and diffuse swelling (hydrops fetalis). Involvement of the central nervous system is common in affected babies, though severe symptoms are rare in infants treated in a timely fashion.
As with syphilis in adults, babies born with the infection can develop long term complications that present years after the initial presentation. Late congenital syphilis is usually seen after a child is at least 2 years of age, and can occur despite appropriate early diagnosis and treatment, though that does decrease the risk and severity. Late disease can involve characteristic changes in the bones of the face, inflammation of the cornea, hearing loss, malformed teeth, scarring around the mouth, abnormal development of some bones and joints, and intellectual disability.
To summarize, congenital syphilis can present as a mild or even asymptomatic infection that is picked up by lab or imaging findings in a newborn born to an infected mother. Those children, if properly treated, usually do well. If early infection is missed, symptoms can arise later in childhood that can be debilitating. Unfortunately, some babies are born already severely ill, or quickly go that route. And many cases of congenital syphilis result in death despite modern medical care.
Of the 1,306 cases reported in 2018, for example, there were 79 stillbirths and 16 infant deaths. In 2019, the number of syphilitic stillbirths increased to 94, and the number of congenital syphilis related infant deaths jumped to 34. Hot off the presses, recently released preliminary data from 2020 reveals that there were likely around 2,100 cases. 139 of these cases resulted in stillbirth or infant death.
Conclusion: This trend needs to end
Congenital syphilis is a preventable disease. These are all completely preventable deaths. There is an inexpensive test used to screen pregnant women and the treatment is penicillin. This is one of last conditions that not only can we use the original antibiotic to treat, we should use it. It is the standard of care to screen pregnant women, but the reality is that many pregnant women are not screened. And even when syphilis is diagnosed during pregnancy, appropriate treatment is not always administered.
Why would this be? As is often the case, it comes down to disparities in healthcare availability and quality. Black, Hispanic, and Native American women are significantly more likely to have late or absent prenatal care, and their babies are 5 times more likely to be diagnosed with congenital syphilis compared to white infants. Part of the problem is the fact that very little money goes towards this problem.
To put things in perspective, HIV in newborns is diagnosed less than 50 times a year compared to the roughly 2,000 cases of baby syphilis. But CDC funding for HIV has steadily increased to almost a billion dollars this year while funding for the prevention of other sexually transmitted infections has been decreasing, with a drop of 40% since 2003, despite these historic increases in incidence. I’m not trying to downplay the overall impact of HIV at all, but the difference in current fiscal emphasis is a bit frustrating.
Health and Human Services has developed a 5 year plan to tackle the rise in syphilis cases, as well as other sexually transmitted infections, and pregnant women are one of the prioritized populations. It will need to plug holes in maternal screening and treatment. One change over the past year in obstetrical medicine was a new recommendation to screen women for syphilis twice during pregnancy rather than only once in the 2nd trimester, but again they need to have access to care to benefit. It will need to stabilize supplies of penicillin formulated for intramuscular injections. And it will need to find ways to reach people who are not seeking prenatal care.