A case-control study conducted in British Columbia showed an increase in the incidence of ocular syphilis over 8 years, and according to researchers, an association between ocular syphilis and early syphilis and HIV infection.
“As clinicians working in the realm of sexual health, it is important to remain vigilant to the diagnosis of syphilis, as it is increasing in many jurisdictions worldwide and — if undiagnosed and/or untreated — has the potential for serious complications including ocular involvement, as presented in the paper,” Troy Grennan, MD, MSc, FRCPC, DTM&H, clinical assistant professor at the University of British Columbia and physician lead of the HIV/STI program and clinical prevention services at the BC Centre for Disease Control, told Infectious Disease News.
Over the last 20 years, syphilis case counts have increased globally. Last fall, Alaska reported its largest syphilis outbreak in at least 40 years, and this year Europe reported a 70% increase in the incidence of syphilis in 7 years. The rate of congenital syphilis has more than doubled since 2013 in the United States, according to the CDC. Although researchers have shown that coinfection with HIV and syphilis can increase the risk for ocular syphilis, a study from 2018 revealed that every year, almost one-third of HIV-positive men who have sex with men (MSM) are not tested for syphilis.
“To our knowledge, this is one of the largest (in terms of number of cases) studies published on ocular syphilis, and the first case-control study,” Grennan said. “Our findings do add to the evidence base related to a likely association between HIV and increased risk for ocular syphilis.”
In an effort to characterize ocular syphilis cases in British Columbia (BC) and determine risk factors for the condition, researchers compared ocular syphilis cases diagnosed in BC with case controls between January 2010 and December 2018.
They identified 6,716 diagnosed syphilis cases, of which 0.98% were ocular syphilis. The median age of patients was 49.5 years and 87.8% were male, of whom 54.6% identified as MSM.
At 42.4%, panuveitis was the most common ophthalmologic diagnosis. Patients who were HIV positive at the time of their syphilis diagnosis comprised 48.5% of the reported ocular syphilis cases compared with 26.4% of controls (P = .001), according to the study.
In 2010 the incidence of ocular syphilis cases was 0.48%, increasing to 0.83% in 2018. Furthermore, the final multivariable model revealed that early syphilis stage (OR = 4.96; 95% CI, 1.86-13.24) — which included primary and secondary infections, — early latent stages (OR = 4.29; 95% CI, 1.62-11.34) and HIV serostatus (OR = 2.16; 95% CI, 1.14-4.09) were associated with ocular syphilis.
“The results of this paper suggest an association exists between ocular syphilis, and both early syphilis infection and HIV infection, which means that a diagnosis of ocular syphilis should prompt clinician consideration of HIV infection, and conversely, there should be a higher clinical suspicion for syphilis-related complications like ocular syphilis in those living with HIV,” Grennan said. “Additionally, many clinicians do not realize that severe complications of syphilis can occur quite early in infection, so these data really reinforce this.” – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.