Global Epidemiology and Subtype Distribution of Blastocystis sp. in Birds: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to evaluate the global epidemiology, subtype (ST) distribution, and zoonotic potential of Blastocystis sp. in birds. A systematic review of the literature up to July 26, 2024, identified 47 articles/98 datasets meeting the inclusion criteria, covering data from 19 countries and over 41 bird species. Total estimates and 95% confidence intervals (CIs) were calculated using a random-effects model. The weighted prevalence of Blastocystis sp. in birds was 26.4% (95% CI: 22.5-30.6%), varying by location and species. The highest pooled prevalence was in guinea fowls at 83.3% (95% CI: 36.9-97.7%), followed by pheasants at 50.4%, flightless birds at 47.8%, peafowls at 41%, exotic birds at 34.4%, chickens at 24.9%, uncategorized birds at 24.4%, Anatidae birds at 24.3%, red-crowned cranes at 19.7%, quails at 15.8%, and pigeons at 12.8%. Subgroup analysis of Blastocystis sp. prevalence was performed based on publication years, countries, continents, WHO regions, and sample sizes. Birds can be the proper source of infection for 20 Blastocystis sp. STs (ST1-ST10, ST13, ST14, ST20, ST21, ST23-ST25, and ST27-ST29), with 12 STs (ST1-ST10, ST14, and ST23) capable of infecting humans. The findings revealed that birds should not be ignored in terms of the possible transmission of Blastocystis sp. zoonotic infections to humans. Moreover, parasitic infections, such as Blastocystis sp., can affect the health of poultry, causing gastrointestinal issues that impact growth and productivity, which requires special attention in this field.