Prevalence and molecular characterization of Giardia duodenalis in small ruminants of Shiraz, southwestern Iran: A zoonotic concern.

Livestock are commonly affected by gastrointestinal protozoan parasites, including Giardia duodenalis. In small ruminants, G. duodenalis infection may decrease carcass weight and dressing percentage. Current study was done to determine the prevalence, assemblage distribution, and zoonotic significance of Giardia infection in sheep and goats in Shiraz, southwestern Iran. In total, 200 fecal samples were randomly collected from 100 sheep and 100 goats in 10 farms in Shiraz, southwest of Iran (June 2021-February 2022) and directly examined for G. duodenalis cyst by saline/iodine wet mount examination using a light microscope (400 ×). Positive samples were further genotyped using a nested-PCR and sequencing methods. A mean prevalence of 5.5% (11/200) was estimated for G. duodenalis infection among small ruminants, with 7% and 4% for sheep and goats, respectively. Next, 9 out of 11 positive samples were amplified and only 5 were successfully sequenced at the tpi locus. Our results showed that 80% (4/5) isolates belonged to assemblage E, while only 20% (1/5) were associated with the assemblage A (subtype AI). Of note, 2 E assemblages were isolated from goats and 2 E assemblages plus 1 assemblage A were isolated from sheep. The major finding in the present study was the isolation of assemblage A from sheep in Shiraz, highlighting the zoonotic transmission of Giardia infection in the study area. In general, the information mentioned in the present study is very limited and more extensive studies in this field are needed to achieve more conclusive results.