A retrospective study of the clinical features of new syphilis infections in an HIV-positive cohort in Alberta, Canada.

OBJECTIVES: Syphilis is a global health concern with an estimated 12 million infections occurring annually. Due to the increasing rates of new syphilis infections being reported in patients infected with HIV, and their higher risk for atypical and severe presentations, periodic screening has been recommended as a routine component of HIV care. We aimed to characterise incident syphilis presentation, serological features and treatment response in a well-defined, HIV-infected population over 11 years. METHODS: Since 2006, as routine practice of both the Southern Alberta Clinic and Calgary STI programmes, syphilis screening has accompanied HIV viral load measures every 4 months. All records of patients who, while in HIV care, either converted from being syphilis seronegative to a confirmed seropositive or were reinfected as evidenced by a fourfold increase in rapid plasma reagin (RPR) after past successful treatment, were reviewed. RESULTS: We identified 249 incident syphilis infections in 194 different individuals infected with HIV; 72% were initial infections whereas 28% were reinfections. Half (50.8%) of the infections were asymptomatic and identified only by routine screening. Symptomatic syphilis was more common when RPR titres were higher (p=0.03). In patients with recurrent syphilis infection, a trend was noted favouring symptomatic presentation (62%, p=0.07). All 10 patients with central nervous system (CNS) syphilis involvement presented with an RPR titre ≥1:32. Following syphilis infection, a decline of 42 cells/mm3 in CD4 (p=0.004) was found, but no significant changes in viral load occurred. No association was found with the stage of syphilis or symptoms at presentation and antiretroviral therapy use, CD4 count or virological suppression. CONCLUSION: Routine screening of our HIV-infected population identified many asymptomatic syphilis infections. The interaction of HIV and syphilis infection appears to be bidirectional with effects noted on both HIV and syphilis clinical and serological markers.

Increasing incidence of syphilis among patients engaged in HIV care in Alberta, Canada: a retrospective clinic-based cohort study.

BACKGROUND: Syphilis is a global health concern disproportionately affecting HIV-infected populations. In Alberta, Canada, the incidence of syphilis in the general population has recently doubled with 25% of these infections occurring in HIV-infected patients. The Southern Alberta HIV Clinic (SAC) and Calgary STI Program (CSTI) analyzed the epidemiologic characteristics of incident syphilis infections in our well-defined, HIV-infected population over 11 years. METHODS: Since 2006, as routine practice of both the Southern Alberta Clinic (SAC) and Calgary STI Programs (CSTI), syphilis screening has accompanied HIV viral load measures every four months. All records of patients who, while in HIV care, either converted from being syphilis seronegative to a confirmed seropositive or were re-infected as evidenced by a four-fold increase in rapid plasma reagin (RPR) after past successful treatment, were reviewed. RESULTS: Incident syphilis was identified 249 times in 194 HIV-infected individuals. There were 36 individuals with repeated infections (28.5% of episodes). Following a prior decline in annual incident syphilis rates, the rates have tripled from 8.08/1000 patient-years (95% confidence interval (CI): 4.14-14.75) in 2011, to 27.04 per 1000 person-years (95% CI: 19.45-36.76) in 2016. Half of the syphilis episodes were asymptomatic. Patients diagnosed with syphilis were twice as likely not to be taking ART and had a higher likelihood of having plasma HIV RNA viral loads > 1000 copies/mL (19%). Incident syphilis was seen predominantly in Caucasians (72%, P < 0.001), males (94%, P < 0.001) and men who have sex with men (MSM) as their HIV risk activity (75%, P < 0.001). CONCLUSIONS: We have highlighted the importance of a regular syphilis screening program in HIV-infected individuals demonstrated by increasing rates of incident syphilis in our region. Targeted preventative strategies should be directed towards HIV-infected populations identified at highest risk, including; MSM, prior alcohol abuse, prior recreational drug use and those with prior syphilis diagnoses.

Reporting on the prevalence of antiretroviral drug resistance in a regional HIV population over 20 years: a word of caution.

BACKGROUND: Failure to achieve complete viral suppression with antiretroviral drugs (ARV) may lead to uncontrolled HIV replication, ARV resistance and negative outcomes. Monitoring and reporting of HIV resistance trends is important but problematic. We examined prevalent resistance rates in an HIV population over 20 years and document how rates may appear to vary greatly based solely on which parameters are utilized. METHODS: We determined the annual use of genotypic antiretroviral resistance testing (GART) from 1995 to 2014 for all patients receiving HIV care in southern Alberta, Canada, and the presence of resistance mutations in those tested. The impact on prevalent resistance rates of using cumulative or latest GART was also determined. RESULTS: Between 1995 and 2014, the number of patients with GART increased from <1% to 71%. Prevalent resistance in patients with GART decreased from a high of 52% in 2003 to 25.8% in 2014. However, if prevalence rates were reported using all active patients as denominator, including those without GART, prevalence increased from 0.7% to 18.5%. Prevalence rates were 7% to 9% higher in any given year if cumulative GART rather than latest GART results were used. CONCLUSIONS: While prevalence resistance rates are decreasing, the precise rates being reported may vary due to increasing number of patients tested annually, using either the entire population as denominator or only patients with GART, and using either last or cumulative GART. Defining these parameters is critical if prevalence is to be compared over time or between HIV populations.