Blastocystis sp. in Small Ruminants: A Universal Systematic Review and Meta-analysis.

PURPOSE: The present review was done to evaluate the prevalence and subtype distribution of Blastocystis infection among small ruminants, at a global perspective.

METHODS

Systematic search was performed in PubMed, Scopus, Google Scholar, and Web of Science until 30th January 2022 and total estimates along with 95% confidence intervals (CIs) were computed using a random-effects model.

RESULTS

Ultimately, the required data were extracted from 25 papers including 19 datasets for each animal. Among 3125 sheep, the Blastocystis prevalence was 25.3% (95% CI 16.1-37.4%) (10 countries), being lower in comparison to that in 2869 examined goats [20.5% (95% CI 11-35.1%)] (12 countries). Regarding STs distribution, fourteen genetically diverse STs of Blastocystis (ST1-ST5, ST7, ST10, ST12, ST14, ST15, ST21, ST23, ST24, ST26) have been reported in sheep, and the highest pooled prevalence was related to ST10 [11 datasets, 57.8% (95% CI 43.7-70.8%)], followed by ST14 [8 datasets, 28.4% (95% CI 20.2-38.4%)], and ST7 [2 datasets, 21.1% (95% CI 4.5-60.3%)]. Compared to sheep, more STs (ST1, ST3-ST7, ST10, ST12, ST14, ST21, ST23-ST26, and ST32) were reported from goats, and the highest weighted frequency was related to ST10 [6 datasets, 45.1% (95% CI: 25.6-66.2%)], followed by ST7 [2 datasets, 40.4% (95% CI 30-51.7%)], and ST14 [4 datasets, 29% (95% CI 15.5-47.7%)]. Out of ten known zoonotic STs reported for Blastocystis (ST1-ST9, and ST12), 7 were isolated from sheep (ST1-ST5, ST7, and ST12) and 7 were reported from goats (ST1, ST3-ST7, ST12).

CONCLUSIONS

Overall, Blastocystis epidemiology in sheep and goats is yet to be elucidated and demands more comprehensive studies.