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Cases of a devastating STI are on the rise and newborns are at high risk for deadly complications.

The deadly and entirely preventable disease has claimed the lives of 42 babies in Australia, and a spike in cases in the US has experts worried about a potential uptick in domestic deaths.

Across the US, syphilis cases have risen sharply over the past decade. In states like New York, infections have increased fivefold since 2013, reflecting a broader nationwide trend.

Last month, several California counties reported particularly alarming rates.

Even more concerning, federal data shows congenital syphilis — when the infection is passed from a pregnant mother to her baby — has skyrocketed by 700% compared to roughly ten years ago.

“As a physician and former public health official, I have never been more concerned about those rates of congenital syphilis,” Jeffrey D. Klausner, a clinical professor of medicine at the Keck School of Medicine of the University of Southern California, wrote in an op-ed for STAT this week.

Left untreated, congenital syphilis can lead to miscarriage, premature birth, skeletal abnormalities, neurological problems, developmental delays, stillbirth or infant death shortly after birth.

In 2024, the CDC reported nearly 4,000 new cases of congenital syphilis, the highest case number since the mid-1950s.

In Australia, the disease has been the cause of 42 infant deaths in the past decade and a source of infection for countless others, leading the country’s Chief Medical Officer to deem it a “communicable disease incident of national significance.”

“It worries us a lot. It’s 100% important not to allow it to spread and to become endemic,” University of Adelaide Emeritus Professor Maciej Henneberg told the outlet.

Syphilis is spread by vaginal, anal or oral sex. Symptoms typically emerge 10 to 90 days after exposure, starting with a painless sore at the site where the bacterium Treponema pallidum enters the body.

The sore can heal on its own in three to six weeks, even as the infection persists.

Syphilis is spread by vaginal, anal or oral sex. Symptoms typically emerge 10 to 90 days after exposure, starting with a painless sore at the site where the bacterium Treponema pallidum enters the body.

In the next stage of infection, symptoms can include a rash, fever, fatigue, sore throat, swollen lymph nodes and hair loss.

If not addressed, it can devastate the brain, heart, and nervous system, leading to blindness, paralysis, and even death.

Syphilis is typically diagnosed with a blood test.

Despite progress in reducing other sexually transmitted infections like chlamydia and gonorrhea, congenital syphilis has continued to climb year after year in the US.

By 2024, it marked 12 consecutive years of increases, reaching its highest level since 1994.

According to the CDC, most cases of congenital syphilis are the result of pregnant women not being tested for syphilis or not being properly treated when they test positive.

Lack of insurance or access, fear of immigration detention, substance use and mental health problems can all create barriers to proper prenatal care and testing.