The number of sexually transmitted diseases (STDs) in Minnesota rose to an all-time high last year, driven largely by a sharp increase in chlamydia cases among young adults and teens.

Sexually transmitted infections have risen fully one-third in the last five years, according to the Minnesota Department of Health’s annual STD report.

The steady rise may reflect weaknesses in public health outreach that could have broader consequences, said state Health Commissioner Dr. Edward Ehlinger. “These rates … provide further evidence that eroding basic local public health services not only hurts our ability to respond to intractable problems like STDs, but also to emerging infectious diseases like Zika virus,” Ehlinger said in a statement Monday.

The Health Department relies on about $1 million in annual federal funding for STD prevention and treatment, but that number has been declining steadily in the past 10 years, said Kris Ehresmann, the department’s director for infectious diseases.

Health officials noted that chlamydia is now the most common communicable disease in Minnesota.

Chlamydia, the nation’s most widespread sexually transmitted disease, accounted for roughly 80 percent of all Minnesota STDs last year, with 21,238 cases, a 7 percent increase in just one year. The majority of those cases occurred in teens and young adults ages 15 to 24.

Gonorrhea was second, with 4,097 cases, and syphilis ranked third, with 654.

Public health officials said they are particularly troubled by the rapid spread of chlamydia, which has increased 61 percent in the last decade.

One risk is that chlamydia sufferers can fail to show symptoms. “People don’t know they have it, and I would say that’s the biggest reason for it spreading so much,” said Dr. Andrew Zinkel, medical director of health plan quality at HealthPartners. Zinkel also cited a decline in the overall number of people receiving STD screenings.

Chlamydia is easily treatable with antibiotics, but it can cause permanent reproductive damage, especially in women, if left untreated.

“It can be frustrating,” said Mark Campbell, co-chairman of an STD prevention advocacy group known as CRUSH. “But you start to see results when you change the minds of people.”

CRUSH, which focuses its outreach efforts on urban teens and young adults, is organizing free STD screenings at 18 Twin Cities clinics on Tuesdays. Last year, almost 100 young adults underwent STD tests, with nine receiving treatment for chlamydia.

Ehlinger said an especially troubling trend was a sharp increase in infections among women, especially women of childbearing age. According to the report, three women passed syphilis to their babies last year.

Overall, the report showed higher infection rates for chlamydia and gonorrhea among communities of color and American Indians when compared to whites. Higher syphilis infection rates turned up among Indian and African-American women, and men who have sex with men.

“Even though this is a difficult subject, people — especially women — need to know about these issues,” Zinkel said. “Every year, when the [STD] report comes out, it’s worse.”

Youssef Rddad is a University of Minnesota student on assignment for the Star Tribune.