Within the Army, like in the overall U.S. population, reportable STI rates have been increasing for the past several years. But when comparing rates between the U.S. and Army populations, Jordan notes the importance of accounting for age and sex differences. This is because the U.S. population includes all ages and is generally evenly split between men and women, whereas the soldier population includes more young adults and 85 percent are men.

Jordan's study found that after controlling for age and sex differences, Army soldiers' chlamydia rates were almost 2 times higher than the rates in U.S. adults. The U.S. adult gonorrhea rates, however, were about 1.35 times higher than the soldier rates. Similar to U.S. population data, soldier STI rates were highest among adults under 25 years, women, and some racial and ethnic minority groups.

"There are many reasons soldiers may have greater STI risk including increased travel, excessive alcohol use, and unique job-related stresses," said Jordan. "Cases may also be more likely to be detected among soldiers, because they have more healthcare access and STI testing than the general population."

Waters explains that the Department of Defense annual chlamydia testing, which often includes a full panel of tests for other STIs like gonorrhea and syphilis, is only required for women under 25 years of age. This is based on recommendations from the U.S. Preventive Services Task Force.

"Since most male Soldiers do not seek STI testing unless they or their partner are experiencing symptoms, we may not be identifying many cases among male soldiers, who can spread the infection to others. So the higher female STI rates we see in reported data may be due to their higher rates of testing," Waters said.

Waters explains that since a majority of these STIs are asymptomatic, prevention and control are challenging, because one cannot generally tell if a person has an STI.

"Those who are infected may not know - so they have a false sense of security, don't feel the need to practice safe sex, and continue to spread the infection," said Waters. "Very importantly, chlamydia, gonorrhea, and syphilis STIs can all be easily detected and cured with a limited course of antibiotics. However, recovery doesn't mean a person can't be re-infected. And there are increasing concerns of antibiotic resistance, especially after repeated treatments."

Recently, the Armed Forces Health Surveillance Division reported a notable decrease in STI rates in 2020. Jordan and her colleagues say this may be partly due to soldiers having fewer social contacts during the pandemic, and – hopefully - also smarter, safer sex practices. But they also point to a decrease in health care access, STI testing, reporting, and contact tracing in 2020.

"Many medical services were put on hold or diverted to support the COVID-19 response, so we don't really know yet if STI rates are actually starting to decrease," said Jordan. "Regardless of the data, we know we still miss a lot of asymptomatic cases, and that STIs continue to be transmitted by millions of Americans, including soldiers, who aren't aware they are infected. The pandemic pointed out weaknesses in the public health system. New solutions need to be considered - like internet-based testing with at-home test kits that are increasingly being used in the civilian sector."

"There are no vaccines for most STIs, including chlamydia, gonorrhea, and syphilis," adds Waters. But these STIs can be easily prevented, tested and treated.

Soldiers with questions about protective measures, like condoms, testing or treatment, are encouraged to contact their medical provider or local installation.