The U.S. rate of maternal syphilis cases rose 221.6%, from 87.2 infections per 100,000 births in 2016 to 280.4 per 100,000 in 2022, according to a new report released Tuesday by the Centers for Disease Control and Prevention’s National Center for Health Statistics. During the same time frame, the total number of annual cases rose from 3,431 to 10,232.

Maternal syphilis rates increased each year of the study period, ranging from a 15% rise from 2017 to 2018 to a 32% rise from 2021 to 2022.

Syphilis rates increased for mothers of all maternal age groups throughout the study period. The largest increase, of 290%, occurred among those under 20, rising from 107.3 per 100,000 births in 2016 to 418.6 per 100,000 in 2022.

Mothers between the ages of 30 and 34 experienced the second-largest percentage increase at 277%, followed by a 239% rise among mothers between the ages of 25 and 29, and a 226% increase in the infection rate among mothers between 20 and 24.

Maternal syphilis rates rose for all mothers regardless of when they began receiving care, though the study found the largest spike occurred among mothers reported to have had no prenatal care, at 298% from 2016 to 2022.

Transmitted through vaginal, anal or oral sex, early stages of syphilis usually result in sores and rashes on affected locations on the body. But if left untreated, syphilis can ultimately lead to more severe conditions such as organ failure, blindness and death.

An estimated 40% of babies born to mothers with untreated syphilis are stillborn or die from the infection as a newborn, according to the CDC.

Rates of maternal syphilis increased in 47 states and Washington, D.C., from 2016 to 2022, more than doubling for 40 states and the district. From 2021 to 2022, the rate of maternal syphilis ranged from a low of 45.8 cases per 100,000 births in Maine to a high of 762.6 per 100,000 in South Dakota.

The rise in syphilis cases comes at a worrying time for some public health experts, who are watching whether Congress will stick to a spending agreement it reached with President Joe Biden last year that would cut $400 million from the public health workforce. That threat could compound current challenges that include ongoing shortages of a drug used to treat congenital syphilis.

Maternal syphilis rates increased across all racial and ethnic groups each year from 2016 to 2022. The largest increase, at 783%, occurred among American Indian and Alaska Native mothers. They also had the highest infection rate of 1,410.5 cases per 100,000 births in 2022.

The maternal syphilis rate among white non-Hispanic mothers rose 315% from 2016 to 2022, while Hispanic mothers experienced an increase of 243%. The rate among Black mothers increased by 149% during the same time frame, compared with a 92% increase among Asian mothers. Asian mothers had the lowest maternal syphilis rate of any racial or ethnic group in 2022, at 73.3 per 100,000.

The latest figures follow a January CDC report that found from 2021 to 2022, there was a more than 30% surge in cases of congenital syphilis, which occurs when a mother passes the infection onto the child during pregnancy. In 2022, a total of 3,755 congenital syphilis infections were reported for a rate 102.5 cases per 100,000 population, the highest reported in the past three decades and a more than 500% increase since 2016.

The latest study notes that from 2017 to 2022, rates of syphilis for women of reproductive age and congenital syphilis “increased by more than 250%.”

Last November, CDC Chief Medical Officer Dr. Debra Houry said increased cases of congenital syphilis marked “missed opportunities” for stakeholders to intervene throughout a woman’s pregnancy.

“These efforts must reach people where they are so that every mother and baby can get the help that they need to stay healthy,” Houry said.