The growing number of syphilis cases in Minnesota women has spawned a new problem: syphilis infections in newborns.

Ten cases of congenital syphilis were found in 2018 in fetuses or newborn babies, a shocking number given that the Minnesota Department of Health leapt into action after just two such cases were reported in 2015. Untreated, syphilis in babies over time can affect the development of children’s eyes, ears and bones and can damage organs.

The 10 cases represented a fivefold increase from 2017, but only a small fraction of the total number of sexually transmitted diseases, or STDs, that were reported Tuesday in the state’s annual report on such infections.

Altogether, the report showed 32,024 cases of chlamydia, gonorrhea and syphilis in 2018, a 3% increase from 2017. Those STDs are primarily spread through unprotected sex and shared use of drug needles or other injectables. The state also reported 286 new cases of HIV in 2018, slightly above the 280 cases in 2017 but below the annual average of 296 new cases since 2014.

To address the transmission of syphilis to babies, state health officials said more and repeated prenatal testing is needed in high-risk women, because antibiotic treatment can prevent the worst outcomes of the infection, including miscarriages, stillbirths and birth defects.

“It is really important that pregnant women are tested for syphilis at least twice during pregnancy, and in some cases, a third time,” said Dr. Ruth Lynfield, state epidemiologist.

Syphilis cases overall declined in Minnesota, from 934 in 2017 to 918 in 2018, reflecting successful public health efforts to increase STD testing and treatment in the highest risk group — men who have sex with other men. But the progress masked a problem in women that has been emerging for a decade.

Early-stage cases of syphilis (those diagnosed within one year of infection) in women increased from 14 in 2010 to 94 last year. The earliest stages can produce skin lesions, rashes and classic fever symptoms. The most devastating symptoms for adults, such as organ and brain damage, occur in the later tertiary stage if the infection goes untreated.

The increase in women correlates to the increase in congenital cases, Lynfield said.

“Many of these women have risk factors such as drug use, such as homelessness. Many of them do not have adequate prenatal care, and what is really tragic is that syphilis can be detected easily. There are reliable tests and it can be treated in pregnancy.”

The nationwide opioid epidemic is playing a role in the increase in female and congenital cases. Case reports to the state showed that many of the congenital cases involved mothers whose syphilis infections occurred due to the use of tainted needles for injections of illicit heroin or other opioid drugs.

The state in February sent updated screening guidelines to obstetricians and other doctors, recommending syphilis screening for pregnant women at least at their first prenatal visits and at visits around 28th weeks of gestation.

Timing is important because antibiotic treatment has the best chance at preventing the worst outcomes of syphilis infections if given four weeks before delivery, said Dr. Farah Cassis-Ghavami, who is a pediatric infectious disease specialist at Children’s Hospitals and Clinics of Minnesota.

“Congenital syphilis is a very scary illness,” she said.

Infants born with the condition receive antibiotics and then blood and spinal fluid tests to make sure the bacteria is eliminated.

The updated state screening guidelines were based on a review of 69 syphilis cases in pregnant women in 2016 and 2017.

The state didn’t know of any cases in that time period in which stillborns had congenital syphilis. However, Lynfield said testing hasn’t been as routine in stillbirths as it has been in live births. The new guidance includes syphilis testing of all women who deliver a stillborn at 20 weeks gestation or later in order to find out how often the infection plays a fatal role.

Eighteen of the reviewed cases involved recent infections and early stages of syphilis. Five of those cases wouldn’t have been found had women only been tested at their first prenatal visits, either. That’s because they were infected through sexual activity after those visits or the syphilis-causing bacteria hadn’t grown to the point that it was detectable.