NEW YORK (AP) — Sharply rising cases of some sexually transmitted diseases — including a 26% rise in new syphilis infections reported last year — are prompting U.S. health officials to call for new prevention and treatment efforts.

“It is imperative that we … work to rebuild, innovate, and expand (STD) prevention in the U.S.,” said Dr. Leandro Mena of the U.S. Centers for Disease Control and Prevention in a speech Monday at a medical conference on sexually transmitted diseases.

Infections rates for some STDs, including gonorrhea and syphilis, have been rising for years. Last year the rate of syphilis cases reached its highest since 1991 and the total number of cases hit its highest since 1948. HIV cases are also on the rise, up 16% last year.

And an international outbreak of monkeypox, which is being spread mainly between men who have sex with other men, has further highlighted the nation’s worsening problem with diseases spread mostly through sex.

David Harvey, executive director of the National Coalition of STD Directors, called the situation “out of control.”

Officials are working on new approaches to the problem, such as home-test kits for some STDs that will make it easier for people to learn they are infected and to take steps to prevent spreading it to others, Mena said.

Another expert said a core part of any effort must work to increase the use of condoms.

“It’s pretty simple. More sexually transmitted infections occur when people are having more unprotected sex,” said Dr. Mike Saag, an infectious disease expert at the University of Alabama at Birmingham.

Syphilis is a bacterial disease that surfaces as genital sores but can ultimately lead to severe symptoms and death if left untreated.

New syphilis infections plummeted in the U.S. starting in the 1940s when antibiotics became widely available. They fell to their lowest ever by 1998, when fewer than 7,000 new cases were reported nationwide. The CDC was so encouraged by the progress it launched a plan to eliminate syphilis in the U.S.