Changing prevalence and risk factors for Toxoplasma gondii seropositivity and disease in persons with HIV at the Southern Alberta Clinic since 1985.

OBJECTIVE

Evaluate prevalence, risk factors and outcomes of T. gondii infection and T. gondii disease among people with HIV living in southern Alberta over 37 years.

METHODS

People with HIV age ≥18 years accessing care at the Southern Alberta Clinic (SAC) (Calgary, Alberta, Canada) between 01/1/1985 and 30/06/2022 with baseline T. gondii serology were included. Poisson regression models with robust variance (approximating log binomial models) estimated crude and adjusted prevalence ratios and 95% confidence intervals comparing risk factors for T. gondii seropositivity (vs. seronegativity). Cases of T. gondii disease were confirmed using laboratory and hospitalization data and evaluated using descriptive statistics.

RESULTS

Among 4424 people with HIV, 3696 (84%) were T. gondii IgG negative and 728 (16%) IgG positive. In adjusted analyses, T. gondii seropositivity was associated with older age, birth outside of North America and lower educational attainment. The prevalence of T. gondii infection increased over time, associated with increased migration of people with HIV from T. gondii endemic regions. T. gondii disease was diagnosed among 36 people with HIV, the majority being male (72%), age <50 years (64%), born outside North America (72%) with a median CD4+ count of 33 cells/mm3 at the time of T. gondii disease diagnosis. Recent HIV diagnosis and those re-engaging in HIV care accounted for 16 cases. Five deaths from T. gondii disease occurred, and 17 experienced long-term disability.

CONCLUSIONS

An increasing prevalence of T. gondii infection was identified among people with HIV at SAC likely due to increasing migration and age of the clinic population. The high mortality of T. gondii disease underscores the ongoing need for strategies to prevent infection and reactivation.