Prevalence and Molecular Characterisation of Cryptosporidium spp. and Giardia duodenalis in Equines in Algeria

Background: Equine cryptosporidiosis and giardiasis remain insufficiently studied in North Africa. In addition, the role of equines as potential hosts of zoonotic subtypes of Cryptosporidium and Giardia duodenalis is not fully understood.

Material and Methods: The present cross-sectional study examined the prevalence and molecular diversity of Cryptosporidium spp. and Giardia duodenalis in equids from Algeria. Between December 2021 and December 2022, a total of 197 faecal samples from 104 horses, 89 donkeys, two ponies, one zebra, and one mule were collected across 46 private farms, two equestrian centres, and one zoological park in eastern and central Algeria. Detection of Cryptosporidium and G. duodenalis in faeces involved both microscopy and PCR. Genotyping and subtyping of Cryptosporidium were performed using sequence analysis of SSU rRNA and gp60 genes, respectively. Giardia duodenalis was screened by qPCR with attempts at genotyping at tpi and bg genes.

Results: Using molecular techniques, the overall prevalence of Cryptosporidium was 34% (horses 31%, donkeys 38%), while G. duodenalis prevalence was 4.6% (horses 2.9%, donkeys 7%). One zebra sample tested positive for Cryptosporidium via PCR, whereas pony and mule samples were negative. Detection rates of Cryptosporidium did not differ significantly by host, age, and farm management of equines, while males showed a higher detection rate compared to females. No significant differences were observed by any epidemiological variable for G. duodenalis. Ten Cryptosporidium-positive samples were genotyped: C. parvum (n=7 by SSU; five subtyped as IIaA20G1R1), C. equi (n=2; VIaA15G3 and VIaA11G2), and C. muris (n=1). Two samples (one horse and one donkey) exhibited mixed C. parvum/C. hominis infections, with gp60 subtypes clustering as C. hominis IkA15G1. Giardia duodenalis-positive samples could not be genotyped due to sequencing failure.

Conclusions: This study presents the first molecular-based prevalence of G. duodenalis in Algerian equids, the initial detection of C. equi subtypes in Algerian horses, C. hominis in donkeys, and Cryptosporidium spp. in a zebra in Algeria. Findings emphasise equines as potential reservoirs of zoonotic C. parvum and advocate for the expansion of One Health surveillance through longitudinal and seasonal sampling to better understand transmission and public health risks.