Nine months after Colorado issued an extraordinary public health order to fight an explosion of syphilis in newborn babies, cases have slowed.
When the order — which expanded testing for the disease — went into effect in April, Colorado health officials were anticipating there being as many as 150 cases of congenital syphilis in 2024. There were 50 cases in 2023 and just seven as recently as 2018.
Instead, state health officials are now projecting that 2024 saw roughly 60 cases of congenital syphilis. (“Projecting” because the famously sneaky disease — which one local doctor has called “the great masquerader” — takes time to formally diagnose.)
“It’s still more cases than we saw in 2023, but it’s a significant slowing,” said Dr. Rachel Herlihy, the state epidemiologist at the Colorado Department of Public Health and Environment.
Syphilis is most commonly thought of as a sexually transmitted disease, but it can also be transmitted to fetuses in utero. The disease, which is caused by a bacterium, is easily treated with antibiotics. Left untreated, the disease can be deadly to both babies and adults.
Last year, Herlihy said there were six stillbirths connected to the disease, as well as two newborns who died shortly after birth. Between 2000 and 2023, 11 people in Colorado died of syphilis, according to state data.
Cases of syphilis among adults have been increased in Colorado, too — a trend also being seen across the country. Because the disease can lie hidden for so long, that has led to many people, including pregnant women, passing the disease along without even knowing they had it.
To combat the surge in congenital syphilis, CDPHE last year issued a public health order requiring medical providers to offer syphilis testing to people who are pregnant during the third trimester and at the time of delivery. It also required an offer of testing when there was a fetal death after 20 weeks of gestation. State law already requires that medical providers offer syphilis testing during the first trimester.
The agency has now codified that testing order in a state Board of Health regulation, ensuring that the increased surveillance effort will continue. CDPHE also continues to work with sheriff’s departments in several counties to provide syphilis testing in jails.
According to preliminary CDPHE data, the total number of syphilis cases in the state in 2024 — around 3,200 cases — increased slightly over 2023. That increase largely came in what are known as late syphilis cases, meaning they were infections that had been lying hidden for some time.
That points to how the testing orders may have helped Colorado start to get ahead of the disease.
In a statement, CDPHE Chief Medical Officer Dr. Ned Calonge said: “The success of the syphilis public health order in significantly reducing projected congenital syphilis cases demonstrates the power of public health interventions and the importance of early and consistent syphilis testing.”