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Risk factors for repeat syphilis infections among gay, bisexual and other men who have sex with men in British Columbia, 2005-2014
Dec 14, 2016 by Jason Wong, Physician Epidemiologist, Clinical Prevention Services, BCCDC
The rates of infectious syphilis have substantially increased over the past decade. Gay, bisexual and other men who have sex with men (gbMSM) represent almost two thirds of all syphilis diagnoses in British Columbia (BC) from 2005 to 2014.
The BC Centre for Disease Control carried out a study to identify factors related to increased risk for repeat syphilis infections among gbMSM in BC.
Using the provincial database, we identified all infectious syphilis diagnoses among gbMSM from 2005 to 2014. Cases were grouped based on the number of diagnoses (i.e. 1, 2, 3, and ≥4) in the 10 year timeframe.
Characteristics of each individual at their first diagnosis were analysed in a statistical model. This was done to identify predictors of multiple infections. We compared age, ethnicity, HIV status, stage of infection (primary, secondary and latent), having a chlamydia or gonorrhea infection at the time of syphilis diagnosis, having a chlamydia or gonorrhea diagnosis before the syphilis diagnosis, and the reported number of sexual partners during the infectious period.
From 2005 to 2014, there were 2,348 syphilis diagnoses among 1,830 gbMSM. 366 individuals (20%) had two or more infections: 267 (73%) had two, 69 (19%) had three and 30 (8%) had four or more infections.
The percentage of those who were HIV positive increased from 47% in those with one diagnosis, to 93% in those with four or more diagnoses. The percentage who reported having only one or two sexual partners decreased from 43% for those with one diagnosis, to 10% for those with four or more diagnoses.
The statistical model showed that being HIV positive and reporting a higher number of partners increased the odds of having a higher number of syphilis diagnoses.
Implications for practice
Other studies have also found HIV status to be a risk factor for repeat syphilis infections. Selective sexual practices based on the HIV status of the individual and his partner, such as unprotected sex with partners of the same HIV status only, may be leading to reduced condom use. This may account for the increased risk of syphilis infections among gbMSM living with HIV. A higher level of syphilis among gbMSM HIV positive sexual networks may be another reason for this finding. [1,2,3]
We acknowledge that regular syphilis screening in people living with HIV, such as with viral load testing, may contribute to the higher number of syphilis diagnoses in this population. This, in turn, may underestimate the risk among HIV negative gbMSM.
Open communication between gbMSM and their health care providers about their sexual practices and partners is important for sexual health. More frequent screening for syphilis among gbMSM living with HIV, and those reporting multiple partners, could help reduce the overall rate of syphilis among gbMSM.
For more information, please contact Dr. Jason Wong.
- Cohen SE, Ng RAC, Katz KA, Bernstein KT, Samuel MC, Kerndt PR, Bolan G. 2012. Repeat syphilis among men who have sex with men in California, 2002-2006: Implications for syphilis elimination efforts. American Journal of Public Health, 102(1), e1-8.
- Phipps W, Kent CK, Kohn R, Klausner JD. 2009. Risk factors for repeat syphilis in men who have sex with men, San Francisco. Sexually Transmitted Diseases, 36(6), 331–5.
- Jansen K, Schmidt AH, Drewes J, Bremer V, Marcus U. 2016. Increased incidence of syphilis in men who have sex with men and risk management strategies, Germany, 2015. Euro Surveillance, 26(43):pii=30382. doi: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.43.30382
Co-authors on this work were: Hasina Samji, Donna Mak, Troy Grennan, Bobbi Brownrigg, Gina Ogilvie, Mel Krajden, Muhammad Morshed and Mark Tyndall
Additional contributor: Stephanie Konrad
Categories: New knowledge