Study findings showed that cases of secondary syphilis are more common among men who have sex with men, or MSM, who practice receptive anal intercourse compared with MSM who practice insertive anal intercourse, revealing a population subset that may require additional screening strategies, researchers said.
According to Vincent J. Cornelisse, PhD, adjunct research associate at Monash University in Melbourne, Australia, and colleagues, this trend is potentially due to the difficulty of identifying syphilitic ulcers in the anal canal.
“This hypothesis is consistent with the observation in heterosexuals, where men present most commonly with primary syphilis and women present more commonly with secondary syphilis, presumably because cervical and vaginal chancres are easily missed,” Cornelisse and colleagues wrote.
They conducted a retrospective analysis of MSM aged 16 years or older who were diagnosed with primary or secondary syphilis at the Melbourne Sexual Health Centre between 2008 and 2017.
The analysis included 559 MSM diagnosed with syphilis, of which 338 were primary infections and 221 were secondary. According to the study, 24% of the men reported not practicing receptive anal intercourse. Of the men with primary infections, 73.1% presented with a penile chancre, whereas 22.8% presented with an anal chancre.
The data showed that 92% of MSM with primary syphilis who did not practice receptive anal intercourse presented with penile chancres, whereas 73% of MSM who exclusively practiced receptive anal intercourse presented with anal chancres.
After adjusting for age, HIV status and condom use, MSM who reported practicing receptive anal intercourse were more likely to present with a secondary infection compared with primary infections (adjusted OR = 3.90; P < .001).
“These data suggest that sexual positioning predicts the site of primary infection, and that when primary syphilis occurs at the anus it is often not recognized by the patient, resulting in delayed presentation and treatment,” Cornelisse and colleagues wrote.
“This study highlighted the need to improve early detection of syphilis in MSM who practice receptive anal intercourse, to shorten the duration of syphilis infectivity, and hence to improve syphilis control. We postulate that perhaps the most practical strategy to improve early detection would be to recommend weekly self-[digital anorectal self-examination] for all MSM who practice receptive anal intercourse with [casual sexual partners]. This strategy needs further investigation to determine acceptability, effectiveness and optimal screening frequency.” – by Marley Ghizzone
Disclosures: Cornelisse reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.