A first-ever look at state-by-state numbers of syphilis infections shows that the sexually transmitted disease is hitting gay men the hardest, particularly those in the South.

The rate of syphilis among gay men is at least 40 times the rate of heterosexual men and the cases of syphilis among gay men continue to account for about 70 percent of all reported infections in men, according to a study released Thursday by the Centers for Disease Control & Prevention during the 2016 STD Conference. 

“These analyses will help CDC and others to better pinpoint efforts to address syphilis among those at greatest risk," said Alex de Voux, an officer with the CDC's Epidemic Intelligence Service who presented the study.

"This data highlights the need to continue syphilis and STD prevention initiatives with concentration in states that are disproportionately affected," she added.

Syphilis has been on the rise among gay men since 2000 and by 2013, men who have sex with men accounted for 75 percent of syphilis cases. But for the first time, the CDC study showed syphilis cases and rates of infection among gay men by state. In the 44 states examined, the syphilis rate for gay men was at least 40 times the rate for straight men. For all states in the study, the syphilis rate for gay men is 107 times the rate for heterosexual men.

What the study found in the South was bleak. The highest rates of syphilis among gay men were seen in North Carolina, Mississippi, Louisiana and South Carolina. Those four states showed syphilis rates among gay men at nearly twice the national average of 309 cases per 100,000 people. Across all states, the rate for heterosexual men is 2.9 per 100,000 people.

The study looked at the rate of syphilis infections among gay men in 44 states, but Georgia wasn't included. That's because Georgia is one of six states that report the sex of the partner in syphilis cases to the National Notifiable Diseases Surveillance System but didn't meet a threshold of reporting it for at least 70 percent of the male cases in 2015. Georgia, though, has been a leader in syphilis among gay men and had a rate nearly twice that of the national average in 2014, according to a CDC report.

The CDC hopes that by calculating the syphilis rate among gay men will help the federal health agency monitor trends in diagnoses, better quantify discrepancies seen in gay man and determine where to best allocate prevention resources. 

A second study presented Thursday showed that among 20 U.S. cities – including Atlanta – syphilis screening among gay men is on the rise. In a six-year span from 2008 to 2014, syphilis screening among gay men increased from 38 percent to 49 percent, according to the study presented by Cyprian Wejnert, a CDC epidemiologist.

Among those screened, positive tests increased from 9 percent to 11 percent, according to the study.

The findings suggest that providers are increasingly aware of the risk and need for annual screening for syphilis among MSM, but rates are still low among MSM at high risk for the disease.
 
Screening was most common among MSM at highest risk, including those who were HIV-positive (68 percent), and those with more than 10 sexual partners in the past 12 months (65 percent). Diagnoses increases were greatest among MSM who were black (9 percent to 14 percent), HIV-positive (15 percent to 21 percent), and those with 10 or more sexual partners (11 percent to 17 percent).

Among gay men, syphilis isn't the only concern. Gonorrhea scores high too. And the CDC warned this week that the treatment for that is showing signs of failing.

UPDATE | The story has been updated to clarify why Georgia was not included in the study. Also, additional clarification was added to show that the rate of syphilis among gay man is 107 times the rate of heterosexual men for all 44 states in the study.