麻豆传媒

ATLANTA -- Rates of primary and secondary syphilis among men who have sex with men (MSM) are dramatically higher than among men with female partners, according to the first state-level analysis of the incidence of the disease.

Across the 44 states included in the analysis, the 2015 syphilis rate among men who have sex with men was an "astounding" 107 times higher than it was among straight men, according to , of the CDC division of STD prevention.

The incidence for MSM was as low as 39 times higher than in other men in Minnesota and reached 342.1 times higher in Hawaii, De Voux reported at the .

The finding comes in the context of a growing epidemic of syphilis occurring almost entirely among MSM. De Voux noted that the national reporting of new syphilis cases was 15% higher in 2014 than 2013 and a further 19% higher in 2015 over 2014.

It's the first time researchers have been able to pin down such differences using data on the size of the MSM population on a state-by-state basis, De Voux told 麻豆传媒. The findings could help refine future prevention efforts, she said.

"It's another tool in the toolbox" for health authorities, she said.

The study is not the first to try to pin down exactly how hard MSM communities have been hit by syphilis; a suggested that the rate of primary and secondary syphilis was about 154 cases per 100,000 MSM annually across 39 states, compared with 2.23 cases per 100,000 other men.

But that study did not have very solid state-by-state data on the size of the MSM population, De Voux said -- a gap that by researchers from Emory University in Atlanta and the CDC who analyzed survey data from several sources.

Indeed, an idea of the size of the MSM population was long in coming, commented of the New York City Department of Health and Mental Hygiene, who was not part of the study but who moderated the session at which it was presented.

"Here we are now, 16 years into this outbreak among MSM," she told 麻豆传媒, "and we are only now getting this MSM denominator. So I think it's very valuable."

"Until you can quantify a problem it's hard to get politicians and other people to listen," she said.

She cautioned that the population estimates are a first cut at the problem and will need validation, but "we have been a long time without knowing the MSM denominator."

De Voux said she and colleagues were able to use the population data, combined with 2015 state-by-state syphilis incidence from the National Notifiable Diseases Surveillance System -- data that include in most cases the sex of sexual partners.

They only included the 44 states reporting the sex of sexual partners in at least 70% of male syphilis cases, De Voux reported, but those accounted for 84% of all reported male syphilis cases last year.

Overall in 2015, there were 17,887 cases among men (and 2,030 among women), with the vast majority of male cases among MSM -- 12,118 versus 2,866, with 2,903 who did not report the sex of their partner.

On that basis, the case ratio for MSM cases versus cases involving men who have sex with women was 4.2.

But when the population denominator was considered, the rate per 100,000 MSM was 309, De Voux said, compared with 2.9 for other men.

That yielded a rate ratio across all 44 states of 107, de Voux said, but with marked variation from state to state.

De Voux cautioned that the study only includes 44 states, so it might not be completely representative of the national picture of adult male primary and secondary syphilis.

As well, she noted, the analysis excluded the men who did not report the sex of their partners but since MSM might be more reluctant than others to disclose that information, the effect could be to underestimate the incidence rates.

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