In 2015, documented cases of sexually transmitted diseases in the US hit the highest number ever in the Centers for Disease Control and Prevention’s records going back to 1941, according to a new report by the agency. It’s the second year in a row with historically high STD levels. However, because only three STDs are routinely reported to the CDC—chlamydia, gonorrhea, and syphilis—the new data may be just a glimpse of the nationwide problem.

Among the three nationally reported STDs, chlamydia had the highest total number of cases, hitting more than 1.5 million in 2015. That total is a 5.9 percent increase from that of 2014. Syphilis saw the largest jump, with a 19 percent increase from 2014 cases, bringing the 2015 total to nearly 24,000. Gonorrhea followed with a 12.8 percent increase, reaching nearly 400,000 cases.

Americans most affected by the STD rise are young people and gay and bisexual men, the agency found. Two-thirds of chlamydia cases and half of gonorrhea cases were among Americans aged 15 to 24. Men who have sex with men were largely behind the rises in gonorrhea and syphilis.

States in the Western region of the country saw some of the biggest jumps in STD rates, but the Southern states still held on to the highest overall rates for all three diseases.

The CDC blamed the historic levels on budget cuts to STD prevention programs as well as clinic closures across the country.

“We have reached a decisive moment for the nation,” Jonathan Mermin, director of CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, said in a statement. “STD rates are rising, and many of the country’s systems for preventing STDs have eroded. We must mobilize, rebuild and expand services—or the human and economic burden will continue to grow.”

While the overall picture is concerning, the data doesn’t capture the prevalence and trends of some other common sexually transmitted infections, namely herpes and human papillomavirus (the most common). According to estimates by the CDC, 79 million Americans are currently infected with HPV and about 14 million get infected each year. While 90 percent of those infections are asymptomatic and clear up on their own within two years, lingering infections can lead to genital warts and cancer. According to physician visit records, the prevalence of these two STIs may be on the rise as well and hitting record levels.

For the three nationally monitored STDs, a course of antibiotics can generally clear the infection, though health officials have raised alarm about gonorrhea cases that are becoming increasingly resistant to antibiotics. If left untreated, all three STDs can develop into long-term health problems. Ongoing syphilis can surface years later as an infection of the central nervous system, leading to dementia, among other problems. Chlamydia and gonorrhea can develop into pelvic inflammatory disease in women, which can result in chronic pain, infertility, and ectopic pregnancies.