Syphilis cases are rising among active-duty troops — to the tune of a 41 percent increase since 2010, according to a new Pentagon report.
In the past month alone, the Navy saw nine new cases, as many as the sea service's diagnoses of Lyme disease, salmonella and giardia combined, according to a separate Defense Department monthly report on infectious diseases in the ranks.
Syphilis is a highly contagious sexually transmitted disease that, if left untreated, can cause blindness, dementia and paralysis.
The Centers for Disease Control and Prevention says the disease was "on the verge of elimination" in the U.S. at the turn of the century. But it has rebounded with a vengeance, particularly among gay males, the CDC found.
As with civilians, the military population has been affected: from January 2010 to August 2015, 2,976 troops were diagnosed with syphilis, according to the Armed Forces Health Surveillance Center.
And the rate of new cases rose by more than 50 percent over that time frame, from just under 31 per 100,000 service members to 47 per 100,000.
Most cases were diagnosed in the early stages, when symptoms included painless sores, rash, sore throat and fever. But 244 cases were considered to be in the advanced stage, when the microorganism can invade bodily organs.
The majority of the cases — 92 percent over the time period — were males.
In the general civilian population, Hispanic and white men have been among the most affected groups, seeing the largest increases in diagnoses in the past 15 years.
In the military population, white males also have seen large increases in new diagnoses, but the black male population remains the hardest-hit group, with high incident rates and 451 cases reported from 2010 to 2015.
Despite the increases, diagnoses within the military remain relatively infrequent compared with other sexually transmitted diseases.
Human papillomavirus infections are the most common sexually transmitted diseases reported in the military health system, followed by chlamydia, herpes simplex and gonorrhea.
HIV-1 infections also occur among U.S. troops; from January 2010 through June 2015, a total of 1,248 active-duty troops were diagnosed with HIV-1, 98 percent of them male.
AFHSC researchers added that while they can't definitively explain the rise in cases, the problem may stem from fewer troops taking safe-sex precautions, and possibly more using the Internet for hookups, or turning to "harm reduction strategies" such as oral sex that lessen the likelihood of passing along HIV but increase the risk of transmission for other diseases.
According to the authors, DoD should "develop and implement syphilis prevention measures targeting troops at risk for contracting" syphilis, and continue an aggressive "partner notification program."