Background
Infectious syphilis rates in British Columbia (BC) are the highest they’ve been in 30 years from 2018 data [1]. Males account for the majority of cases, and in 2016 gay, bisexual and other men who have sex with men (gbMSM) represented 86% of new cases [2] – gbMSM living with HIV are disproportionately burdened.
Syphilis infection may lead to multi-stage disease that can affect nearly any organ system, including the eyes (ocular syphilis) [3,4]. When detected early, syphilis is treatable. However, delayed treatment of ocular syphilis can result in permanent vision loss.
Prompted by reports of ocular syphilis outbreaks in the United States, the United Kingdom, Australia, and elsewhere, a team at BC Centre for Disease Control reviewed cases of syphilis and ocular syphilis. The case-control study included cases diagnosed in BC between January 2010 and December 2018, and compared health-related information between people with ocular syphilis and people with syphilis who did not have eye complications.
Summary of evidence
Demographics
During the study period, a total of 6,716 people were diagnosed with syphilis, where 74% of cases were considered infectious (occurring in the primary, secondary or early latent stages of syphilis). Sixty six people were diagnosed with ocular syphilis, which represented about 1% of all syphilis cases and 1.34% of infectious syphilis cases. The median age of ocular syphilis cases was about 50 years old.
Notable Trends
- The majority of people with syphilis and ocular syphilis were gbMSM.
- The proportion of syphilis cases who developed ocular syphilis increased between 2010 and 2018, from 0.48% to 0.83%, respectively.
- The majority of ocular syphilis cases occurred during an infectious syphilis stage.
- Ocular syphilis cases typically had higher rapid plasma reagin (RPR) titres, which is a test that is used to identify possible syphilis cases.
Association with HIV
Nearly half of those with ocular syphilis were living with HIV. In contrast, among those who had syphilis but no ocular involvement, 26% were also living with HIV.
Slightly more than half (55%) of people living with HIV and ocular syphilis had a detectable HIV viral load which is greater than 50 copies/mL. In contrast, only 22% of people living with HIV and syphilis without ocular involvement had a viral load greater than 50 copies/mL.
Implications for practice
This study found that ocular syphilis was most strongly associated with HIV-positive status and infectious syphilis stage. It is recommended that clinicians look for ocular symptoms in those with infectious syphilis and high RPR titres so they can be treated. These findings underscore the benefits of offering HIV testing when HIV status is unknown for people with ocular syphilis given the high proportion of co-infection.
For further information
- Hamze, H., et al., HIV seropositivity and early syphilis stage associated with ocular syphilis diagnosis: A case-control study in British Columbia, Canada, 2010-2018. Clinical Infectious Diseases, 2019.
- CDC. Syphilis (Treponema pallidum). 2018 July 15, 2019; Available from: https://wwwn.cdc.gov/nndss/conditions/syphilis/case-definition/2018/.
- Public Health Agency of Canada. Canadian Guidelines on Sexually Transmitted Infections- Management and treatment of specific infections – Syphilis. 2018 July 18, 2019; Available from: https://www.canada.ca/en/public-health/services/infectious-diseases/sexual-health-sexually-transmitted-infections/canadian-guidelines/sexually-transmitted-infections/canadian-guidelines-sexually-transmitted-infections-27.html.
References
- BC Centre for Disease Control. (2019). BC experiencing highest rates of infectious syphilis in the last 30 years. Retrieved from http://www.bccdc.ca/about/news-stories/news-releases/2019/bc-experiencing-highest-rates-of-infectious-syphilis-in-the-last-30-years.
- BC Centre for Disease Control. (2018). STI in British Columbia: Annual Surveillance Report 2016. Retrieved from http://www.bccdc.ca/search?k=sti%20annual%20report.
- Shalaby, I.A., Syphilitic Uveitis in Human Immunodeficiency Virus—Infected Patients. Archives of ophthalmology (1960), 1997. 115(4): p. 469-473.
- Tamesis, R.R. and C.S. Foster, Ocular Syphilis. Ophthalmology, 1990. 97(10): p. 1281-1287.