Global prevalence and genetic diversity of Cryptosporidium spp. in pigeons: A systematic review and meta-analysis.

Abstract

Cryptosporidium spp. are globally important protozoan pathogens infecting many vertebrates, including birds. Pigeons, which live in close contact with humans, may contribute to environmental contamination and zoonotic transmission, yet their infection patterns have not been comprehensively reviewed. We conducted a systematic search of international databases from inception to November 25, 2025, identifying 52 eligible studies. A random-effects meta-analysis was performed using Comprehensive Meta-Analysis (CMA) software, with subgroup analyses by continent, country, publication year, sample size, age, sex, and diagnostic method. Heterogeneity was assessed using the I² statistic, publication bias using funnel plots and Egger's test, and robustness through sensitivity analysis. Univariable random-effects meta-regression examined potential sources of heterogeneity. The pooled global prevalence of Cryptosporidium spp. in pigeons was 10 % (95 % CI: 6.9-14.4 %), with substantial heterogeneity (I² = 95.2 %). Prevalence differed significantly by continent, publication year, and sample size. Higher infection rates were reported in younger pigeons, whereas sex and diagnostic method showed minimal impact. Sequential study exclusion did not materially alter the pooled estimate. Funnel-plot asymmetry and Egger's test (p = 0.01) indicated significant publication bias. Meta-regression identified publication year and sample size as significant predictors of variability, though considerable residual heterogeneity persisted. Winter exhibited the highest detection rate. Eight species and seven gp60 subtypes were reported, including five zoonotic species (C. meleagridis, C. parvum, C. hominis, C. andersoni, and C. muris). These findings highlight the potential zoonotic relevance of Cryptosporidium spp. detected in pigeons and reinforce the need for improved surveillance and molecular characterization within a One Health framework.