Assessment of Sexual Behaviour Among HIV-Syphilis Coinfected Individuals From Designated Sexually Transmitted...

Sexually transmitted infections remain a significant concern among people living with HIV (PLHIV), with syphilis emerging as a common coinfection globally, particularly among men who have sex with men (MSM) and anti-retroviral therapy (ART)-naïve individuals. Understanding the socio-demographic and behavioural characteristics of HIV-syphilis coinfected individuals is important for guiding targeted prevention strategies. This study aimed to examine the associations between socio-demographic characteristics, sexual behaviour patterns, and treatment status among HIV-syphilis coinfected individuals, with a focus on gender differences and MSM versus non-MSM.

This secondary data analysis included 2,209 PLHIV coinfected with syphilis registered at 27 designated sexually transmitted infections/reproductive tract infection clinics (DSRCs) in Mumbai under the National AIDS and STI Control Programme from April 1, 2022, to March 31, 2025. Socio-demographic, behavioural, and clinical variables were extracted from programme records and analyzed in R, with associations assessed using chi-square or Fisher's exact tests, as applicable, and multivariable logistic regression was performed, at a significance level of p<0.05. Ethical approval was obtained from the Mumbai District AIDS Control Society, and data were anonymized before analysis.

Among the 2,209 coinfected individuals, 1822 (82.5%) were males, 273 (12.4%) were females, and 114 (5.2%) were transgender individuals. The majority belonged to the 26-35 year age group (n = 767, 34.7%). Significant differences were observed across gender groups in education, marital status, sexual practices, partner types, condom use, and treatment status (p < 0.05). Vaginal intercourse was the most common sexual act overall (n = 1434, 76.6%), while anal and oral sexual practices were more frequently reported among males and transgender individuals (p < 0.001). Spousal partners were the most commonly reported type of partner (n = 886, 51.0%), followed by commercial (n = 808, 45.9%) and casual partners (n = 794, 44.3%). Consistent condom use was highest with casual partners (n = 377, 49.2%) but lower with regular partners (n = 71, 30.6%). Among males, 398 (21.8%) identified as MSM, who were significantly younger, more educated, and more likely to report anal sex and casual partners (p < 0.05). Overall, 60.3% (n = 1332) of participants were ART-experienced. In multivariable analysis, MSM status was independently associated with unmarried status, higher education, and anal intercourse. Increasing age, male and transgender identity were associated with higher odds of being ART-experienced, while engagement in commercial partnerships and anal intercourse were associated with lower odds.

HIV-syphilis coinfection in our study appears to be sustained through overlapping sexual networks involving casual, commercial, and marital partnerships combined with inconsistent condom use. Strengthened screening for syphilis, targeted prevention interventions, and behavioural counselling for risk reduction among PLHIV are essential to reduce ongoing transmission.