Prevalence of Giardia duodenalis in people with disability: a systematic review and meta-analysis

Giardia duodenalis is a globally prevalent protozoan causing asymptomatic to severe gastrointestinal illness. Despite increased vulnerability due to hygiene challenges, caregiver dependence and institutionalization, its burden among individuals with disabilities remains underexplored. A systematic search of international databases was conducted from inception to 2 September 2025. Eligible studies reporting the prevalence or risk factors of G. duodenalis in any disability group were included. Random effects models estimated pooled prevalence and odds ratios (ORs), with subgroup and meta-regression analyses exploring prevalence and heterogeneity. The pooled prevalence of G. duodenalis was 8.2% (95% confidence interval [CI] 6 to 11). Case-control evidence suggested a non-significant tendency toward higher risk compared with controls (OR 2.03 [95% CI 0.9 to 4.5]). Higher prevalence was observed in sensory disabilities, smaller studies, pre-2010 publications and high-Human Development Index regions. Meta-regression revealed that smaller studies tended to report higher prevalence and sample size explained part of the variation across studies. Funnel plot asymmetry and Egger's test (p<0.05) suggested small-study effects. Limited molecular data identified assemblage B in both disabled and control groups. Larger studies incorporating molecular diagnostic and genotyping approaches, along with strengthened sanitation and caregiver-focused interventions, are needed to mitigate transmission in this vulnerable group.