Neurosyphilis among people with and without HIV infection: A Danish nationwide prospective, population-based cohort study 2015–2021

Comparative data on clinical presentation, laboratory characteristics, treatment, and outcome of neurosyphilis (NS) in people living with HIV (PLWH) and NS patients without HIV are scarce. Nationwide, population-based, prospective cohort study on all adults with NS diagnosed between 2015 and 2021 at departments of infectious diseases in Denmark. We identified 108 patients with NS, which equals a yearly incidence of 0.3/100,000 adults. The median age was 49 years, 85 (79%) were male, 43 (40%) were men having sex with men and 20 (22%) were PLWH. Ninety-five (88%) had early NS, 37 (34%) had ocular or ocular and otogenic NS, and 27 (25%) had symptomatic meningitis. Most common symptoms were visual disturbance (44%), skin rash (40%), fatigue (26%) and chancre (17%). Median CSF leukocyte count was 27 × 106 cells/L. PLWH less often had neurological deficits (p = 0.02). Unfavorable outcome was observed in 23 (21%) at discharge of whom 0 were PLWH (p = 0.01). Among the 88 NS patients without HIV a CSF leukocyte count of ≥ 30 × 106 cells/L was associated with unfavorable outcome (OR = 3.3 (95% confidence interval: 1.1–10.4)). PLWH with NS have better outcomes than NS patients without HIV infection.