Global distribution of Echinococcus granulosus genotypes in domestic and wild canids: a systematic review and meta-analysis

Abstract

The current systematic review and meta-analysis demonstrate the genotypic distribution of canine echinococcosis worldwide. Studies published from the inception until 21 May 2021 were screened, relevant articles were selected and the random-effect model was used to draw forest plots with 95% confidence intervals (CIs). Totally, 44 articles were included, mostly examined dogs (37 records), followed by wolf (8 records), jackal (7 records), fox (3 records), pump fox (3 records) and coyote (1 record). Echinococcus granulosus sensu stricto (G1–G3) and G6/7 cluster of Echinococcus canadensis were the most common genotypes among canids. Most studies were conducted in Asia and Europe with 17 and 15 datasets, respectively. Exclusively, Iran possessed the highest number of studies (10 records). Meta-analysis showed that the pooled molecular prevalence of echinococcosis was 33.82% (95% CI 24.50–43.83%). Also, the highest and lowest prevalence of canine echinococcosis was calculated for South America (66.03%; 95% CI 25.67–95.85%) and Europe (19.01%; 95% CI 9.95–30.16%). Additionally, there were statistically significant differences between the global prevalence of echinococcosis in canines and publication year, continent, country, sample type, host and molecular test. These findings will elevate our knowledge on the poorly known canine echinococcosis worldwide.

Keywords: Canine echinococcosis; E. canadensis; E. granulosus sensu lato; E. granulosus sensu stricto; genotype diversity; meta-analysis; systematic review.

Graphical abstract

Fig. 1.

PRISMA flow diagram describing included/excluded studies explored until 21 May 2021.

Fig. 2.

Forest plot of the pooled prevalence of canine echinococcosis worldwide until 21 May 2021.

Fig. 3.

A bias assessment plot from Egger for the prevalence of canine echinococcosis in examined domestic/wild canids worldwide, until 21 May 2021.

Fig. 4.

Phylogenetic tree of E. granulosus s.l. sequences isolated from canine species, based on COX1 gene analysis, until 21 May 2021. The percentage of trees in which the associated taxa clustered together is shown next to the branches. Those illustrated with animal icons are derived from included papers in our study. The percentage of trees in which the associated taxa clustered together is shown next to the branches. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site.