Increases in HIV infections, and in cases of syphilis passed from mothers to newborns, marred an otherwise hopeful decline in sexually transmitted diseases in Minnesota last year.

Minnesota's state epidemiologist called those two increases "troubling," because they occurred despite awareness of the risks and opportunities to prevent them. And while new cases of chlamydia, gonorrhea and syphilis declined in Minnesota from 32,072 in 2022 to 31,232 last year, that still reflected near-record levels of transmission, according to a report released Thursday.

"We urge anyone who is sexually active to reduce the risk to themselves and others with prevention steps, testing and treatment," said Dr. Ruth Lynfield, state epidemiologist and medical director for the Minnesota Department of Health.

New cases of HIV, or human immunodeficiency virus, declined for more than a decade in Minnesota until 2019. The trend then reversed, largely because of outbreaks identified among intravenous-drug users and men who have sex with other men in Duluth and in homeless encampments in the Twin Cities. HIV is transmitted through direct contact with infected blood or other bodily fluids such as breast milk or semen.

The 324 newly diagnosed HIV infections last year made up the highest total since 2010, and partly reflected the spread of the virus in new populations. Hispanic Minnesotans made up 22% of new infections last year, compared to 14% over the prior five years.

Public health officials had previously identified this minority population as a challenge, because Catholic roots and cultural attitudes made it difficult for Hispanic men who have sex with other men to disclose infections and seek testing. Hispanic men with HIV historically have been more likely to progress to AIDS, which is diagnosed when a high enough concentration of the virus is found in blood.

In 2023, 31 Minnesotans died as a result of underlying HIV infections. That number has declined because of drug cocktails that can reduce the viral load to undetectable levels. A record 9,996 Minnesotans were living with their diagnosed infections in the state last year. Another estimated 1,100 people are infected but haven't been diagnosed.

The 91 people diagnosed with HIV who progressed to AIDS last year was the highest total since 2014, reflecting missed treatment opportunities. Another 66 Minnesotans already had AIDS last year at the time their infections were first identified.

STD testing declined when the COVID-19 pandemic emerged in 2020, but then surged in 2021 and 2022, said Christine Jones, manager of the state health department's STD surveillance section. So, the overall drop in STDs in Minnesota last year could just reflect a return to more normal levels of testing.

"While we're very glad to see these cases decrease a bit, it's still a concern," she said.

Infection rates remained substantially higher among Minnesota's racial minority populations, but risk groups shifted somewhat.

Chlamydia is the state's most commonly found STD — a leading cause of fertility problems that is often first identified in young adults. Six in 10 new cases last year were in Minnesotans younger than 25. But the diagnosis of HIV is starting to trend younger as well; one in five cases were found in that younger population last year.

The 29 cases of congenital syphilis that were identified last year made up the highest total in at least 40 years. Jones said the STD is most commonly found in men who have sex with men, but its emergence among couples at childbearing ages has increased the risk for newborns — who then receive antibiotic treatment after birth.

"It's the outcome of that," she said. "You see an increase in that population, you're going to see an increase in congenital syphilis cases."

Public health efforts are seeking to expand testing and prevention for all STDs, she noted. Congenital syphilis can be prevented if infections in pregnant women are detected and treated at least 30 days before they give birth. State leaders are studying how and where to provide early testing and treatment to pregnant women who don't seek traditional prenatal care.