Heterosexual syphilis transmission and methamphetamine use in women, and men who have sex with women only (MSW) have increased rapidly in recent years, becoming intersecting epidemics that will necessitate collaboration between substance use disorder programs and programs for sexually transmitted diseases, according to a study published in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.

From 2013 to 2017, the rate of primary and secondary syphilis cases in the United States rose by 72.7%, from approximately 5.5 to 9.5 cases per 100,000. The highest primary and secondary syphilis rates has been seen in bisexual, gay, and other men who have sex with men (MSM), and MSM accounted for the majority of syphilis cases in 2017. However, in the aforementioned time period, the rate in women increased by 155.6%, from 0.9 to 2.3 cases per 100,000; the rate in all men increased by 65.7%, from 10.2 to 16.9 cases per 100,000.

Further analysis of nationwide primary and secondary syphilis surveillance data from 2013 to 2017 found that the reported use of injection drugs, methamphetamine, and heroin more than doubled in women and MSW with such infection.  In 2017, 5.8% of women with primary and secondary syphilis had used heroin, 10.5% had used injection drugs, and 16.6% had used methamphetamine in the prior 12 months. Similar trends were seen for MSW, but not MSM, indicating that a substantial percentage of heterosexual transmission of syphilis is occurring between individuals using these drugs, particularly methamphetamine. Of note, the percentage of MSM with primary and secondary syphilis who reports use of methamphetamines decreased from 9.2% to 8.0%.

Limitations include a lack of data on opioid use other than heroin, a lack of inclusion of cases with incomplete data on variables of interest, and the potential for participants to avoid disclosing drug use due to its stigma.

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Study investigators concluded, “Heterosexual syphilis transmission and drug use, particularly methamphetamine use, are intersecting epidemics. Collaboration between sexually transmitted disease control programs and substance use disorder services providers will be essential to address recent increases in heterosexual syphilis transmission.”

Reference

Kidd SE, Grey JA, Torrone EA, Weinstock HS. Increased methamphetamine, injection drug, and heroin use among women and heterosexual men with primary and secondary syphilis — United States, 2013-2017. Morb Mortal Wkly Rep. 2019; 68(6):144-148.