Describing trends of sexually transmitted blood borne co-infections in Nova Scotia from 2019 to 2023.

OBJECTIVES: (1) To describe sexually transmitted and blood-borne (STBB) co-infection events in Nova Scotia from 2019 to 2023. (2) To compare the demographics and risk factors of individuals presenting with a single STBB Infection (STBBI) vs an STBB co-infection event over the same period. METHODS: We conducted a population-based descriptive study of residents in Nova Scotia diagnosed with an STBBI between January 2019 and December 2023. Data were pulled from Panorama, Nova Scotia Public Health's information management system. Nova Scotia Surveillance Guidelines were used to define confirmed cases of each included STBBI (human immunodeficiency (HIV), hepatitis B (HBV), and hepatitis C (HCV) viruses, chlamydia, gonorrhea, and syphilis). We defined a co-infection event as infection by at least two separate STBBI pathogens within a 90-day period. We summarized demographic characteristics of individuals who experienced co-infection events and used the chi-square goodness-of-fit test to determine whether there was a significant difference in risk factor distribution compared to those who had a single STBBI (non-co-infection events). RESULTS: There were 320 STBB co-infection events from 2019 to 2023, with the reported rate of 6.7 co-infections per 100,000 population in 2019 and 10.7 co-infections per 100,000 population in 2023. A chlamydia-gonorrhea co-infection event was the most prevalent STBB co-infection in Nova Scotia, representing 72% of all events over the study period. CONCLUSION: Creating awareness of prevalent STBB co-infection events, trends, and those most susceptible to STBB co-infections within Nova Scotia is important to inform public health strategies and awareness programs.