CDC Releases State-Specific Rates of Primary & Secondary Syphilis Among MSM

The CDC has released the first estimates of state-specific rates of primary and secondary syphilis among men who have sex with men.

In the latest Morbidity and Mortality Weekly Report (MMWR), the Centers for Disease Control and Prevention (CDC) reported the first state-specific rates of primary and secondary syphilis in the United States for men who have sex with men (MSM). The data suggests that there is a “disproportionate incidence of disease” among this population.

Syphilis is a sexually-transmitted infection that is often referred to as “The Great Pretender,” because often, the infection’s symptoms can look similar to those of several other diseases. Due to this, many individuals may not receive needed treatment as quickly as they should, and, if left untreated, the disease can result in several serious health complications.

In the MMWR, the CDC reports that, “the overall rate of primary and secondary syphilis among MSM was 106.0 times the rate among men who have sex with women only, and 167.5 times the rate among women.” This means that syphilis disproportionately impacts MSM.

The analysis was limited to “44 states that included sex of sex partner in ≥70% of male primary and secondary syphilis case reports for 2015,” according to the report. In 2015, 23,872 primary and secondary cases were reported in the United States; the cases included in the analysis accounted for 83.4% of them. Among the cases reported in the 44 states, 60.8%, or 12,118 were MSM (which included 54.9%, or 10,942, among men who only had sex with men and 5.9%, or 1,176, among men who had sex with men and women).

The CDC also noted that the incidence of syphilis that was reported was higher among MSM than among men who have sex with women only; this was true for all states. Although primary and secondary syphilis rates among MSM “varied by US Census region and by state,” the CDC reported that the rates were highest in the South and West. In fact, four of the five states with the highest rates of primary and secondary syphilis were southern states: Louisiana, Mississippi, North Carolina, and South Carolina. The lowest rate was in Alaska (73.1), and even that “exceeded the highest overall US primary and secondary syphilis rate (70.9) which had been reported back in 1946.

“The geographic variation highlights the importance of these data for state and local health departments, which can use these data to better understand their local syphilis epidemiology and target resources and interventions to address disparities between MSM and other population groups,” the CDC reported. In addition, the CDC noted that although the estimated state-specific rates of primary and secondary syphilis among men who only have sex with women was lower than those rates among MSM, they “also have implications for the rates of syphilis among women.” In fact, “trends in congenital syphilis tend to follow trends in the incidence of primary and secondary syphilis among women of reproductive age, which has been increasing recently.” This is important to keep in mind, as congenital syphilis can result in miscarriage, stillbirth, prematurity, low birth weight, or even death shortly after birth.

The CDC mentions at least four limitations to their analyses. The first is that it was “restricted to states where the sex of sex partners (male, female, or both) was reported for ≥70% of male cases of primary and secondary syphilis cases during 2015.” They note that although 83.4% of the cases reported in the United States for 2015 had been included, it might not be “representative” of all individuals who had been diagnosed at that time. The second limitation is that “the denominators used in calculating the rates of primary and secondary syphilis were estimates of the number of MSM in each state, based on the reporting of same-sex households in the American Community Survey.” If the number of same-sex households were underreported that could result in an “underestimation of the MSM population and an overestimation” of syphilis rates. Also, cases of syphilis in men whose sex partners’ sex was unknown were not included in the calculations for either MSM or men who just had sex with women; if MSM are underreporting the sex of their partner, it’s possible that it can result in an underestimation of syphilis rates. Lastly, “primary and secondary case report data likely underestimate the actual number of incident syphilis infections in the United States,” simply because many infections are left undiagnosed, and thus, never reported.

The CDC notes that the findings are consistent with reports that had been made in the past which suggested that there are disparities when it comes to syphilis rates among MSM and men who only have sex with women. Now, with state-specific data pertaining to MSM population sizes as well as case counts, researchers can draw comparisons of both primary and secondary syphilis rates by state. MSM had higher rates of syphilis in all states compared with men who only had sex with women; however, the data suggests that rates in southern states are particularly high, which means that they must strengthen preventive measures against the disease. Taking into consideration the fact that MSM account for most of the reported syphilis cases (both primary and secondary) prevention programs should address this population specifically.

“It is important that both private and public health care providers 1) recognize the signs and symptoms of syphilis, 2) conduct a comprehensive sexual history, 3) screen all sexually active MSM for syphilis at least annually, and 4) provide timely treatment according to national sexually transmitted diseases treatment guidelines (3). Part of this sexual history includes eliciting information on sexual practices and the sex of patients’ sex partners,” they concluded.