(P211) Monkeypox/Syphilis coinfection- is this the new challenge in combating the Great Imitator?

Background: Clinical presentation of monkeypox (mpox) is similar to syphilis or herpes simplex infection. Throughout the 2022 global outbreak, most individuals have presented with genital, rectal, and/or oral lesions. There is limited information on the syphilis/mpox co-infections. The objective of this study was to assess the recent epidemiology of mpox/syphilis co-infection in Chicago, IL. 

Methods: Surveillance data for mpox and syphilis cases reported to the Chicago Department of Public Health (CDPH) were analyzed. Data were matched between Illinois National Electronic Disease Surveillance System (INEDSS) used for mpox and Chicago Health Information Management System (CHIMS) for syphilis. Data were analyzed using SAS version 9.4.

Results: Between June 1 and December 31, 2022, in total, 1,115 total mpox cases were reported to the CDPH.  Approximately 43 % (479/1,115) of mpox cases were co-infected with HIV and 15.3% (171) of mpox cases were diagnosed with syphilis in the past 12 months. All mpox/syphilis co-infected cases were in men, with 83.7% in persons identifying as gay, bisexual and other men who have sex with men (MSM). Approximately 74% of mpox/syphilis co-infected cases were among individuals in age group 20-39 (Median age = 33. IQR=10); 38% were in Non-Hispanic Blacks, 35.7% in Non- Hispanic Whites, and 23.4% in Hispanic. Approximately 25% (42/171) of mpox/syphilis co-infected cases were diagnosed with Primary and Secondary (P&S) syphilis, with 73.8% of cases among MSM. 78.6% of cases were between the ages of 20-39 (Median age=32. IQR=9), 40.5% of cases were Non-Hispanic Blacks, 31% Non-Hispanic Whites, and 23.8% Hispanic. Approximately 62% of mpox/P&S syphilis cases were also coinfected with HIV.

Conclusions: Data highlights the need for syphilis screening among sexually active MSM presenting with the clinical signs/symptoms consistent with mpox. Additionally, it offers a cautionary tale for medical practitioners as P&S Syphilis has many similar signs and symptoms to mpox, which must be thoroughly considered during differential diagnosis.