# Occurrence and Genetic Diversity of Cryptosporidium spp. and Giardia intestinalis from Yaks (Bos grunniens) in Ganzi, Sichuan Province, China

## TL;DR

This study investigates the presence and genetic diversity of two protozoan parasites in yaks from China's Ganzi region.

## Contribution

The study reports the first detailed survey of Cryptosporidium and Giardia in yaks in Ganzi, identifying specific species and genotypes.

## Key findings

- Cryptosporidium spp. was detected in 7.2% of yak samples, with C. andersoni, C. ryanae, and C. bovis identified.
- Giardia intestinalis was found in 15.7% of samples, with assemblage E being the only genotype detected.
- Co-infection with both parasites was observed in five samples.

## Abstract

Cryptosporidium spp. and Giardia intestinalis are important zoonotic protozoa that are closely related to diarrhea and cause considerable economic losses in the livestock breeding industry. Ganzi is one of the main production areas for yaks in China, but there have been few reports on the occurrence of Cryptosporidium spp. and G. intestinalis in yaks. This study used PCR-based sequencing techniques to survey the prevalence and species/genotypes of Cryptosporidium spp. and G. intestinalis in faecal samples from 223 yaks in Ganzi, Sichuan Province. The positive rate of Cryptosporidium spp. was 7.2% (16/223), with the highest positive rate of yaks found in Yajiang (37%, 10/27), which was significantly higher than that in Litang (3.1%, 4/130) and Seda (3%, 2/66). The positive rate of Cryptosporidium spp. in young animals aged <6 months (20.5%, 8/39) was significantly higher than that in older animals aged 12–23 months (0; 0/43) and >24 months (3.3%, 3/90). Three Cryptosporidium species were found by sequence analysis of 18S rRNA locus, namely C. andersoni, C. ryanae, and C. bovis. The total positive rate of G. intestinalis was 15.7% (35/223), with significant differences identified between Yajiang (40.7%, 11/27), Litang (17.7%, 23/130), and Seda (1.5%, 1/66). One genotype (assemblage E) was found by analyzing the sequence of gdh, bg, and tpi loci. Meanwhile, co-infection of Cryptosporidium spp. and Giardia intestinalis was identified in five samples. The present study explores the infection of Cryptosporidium spp. and G. intestinalis from yaks in Ganzi, aiming to enrich our understanding of the occurrence of these protozoa in livestock.