HIV and syphilis: incidence rate of co-infection and syphilis re-infection in a cohort of newly diagnosed HIV patients.

Abstract

BACKGROUND\nSyphilis represents a major public health concern disproportionately affecting HIV positive patients and in many cases both infections are newly diagnosed at the same time. To date, limited studies are available on syphilis incidence in patients with a new HIV diagnosis.\n\n\nMETHODS\nPatients newly diagnosed with HIV in 2010-2018 were included in the study and screening tests for syphilis were performed at baseline and at least once a year. Primary aims were to analyse the incidence rate of HIV-syphilis co-infection and syphilis re-infection. Secondary objective was to identify characteristics independently associated with co-infection and re-infection.\n\n\nRESULTS\nOf 500 newly diagnosed HIV patients, 20% presented a concomitant positive syphilis serology. Among them, 54 patients had a serology indicative for an active syphilis requiring therapy, while 46 had a history of prior treatments. The independent factors for syphilis acquisition were: MSM contact (OR:2.64; 95%CI 1.48-4.72; p<0.001), male gender (OR:2.43; 95%CI 1.08-5.48; p=0.032), and age (OR:1.03; 95%CI 1.01-1.05; p=0.005 per year increasing). Presence of syphilis at the time of HIV diagnosis remained fairly stable during the study period (P for trend, p=0.689). We observed 52 syphilis re-infections related to 37 people. Patients with at least one re-infection were all males and 86.5% MSM.\n\n\nCONCLUSIONS\nMales and MSM with HIV presented high rates of syphilis co-infection and re-infection suggesting persistent high-risk sexual behaviours and the need for appropriate intervention strategies in order to early detect and treat syphilis avoiding life-threatening complications and the spread of the infection in the community.