Abstract
Background:
Giardia is the most prevalent flagellated protozoa in humans and other mammals. It causes significant economic losses in livestock, including water buffaloes.

Aim:
This study aimed to determine the prevalence rate of Giardia intestinalis in water buffaloes (Bubalus bubalis) using microscopic and molecular techniques and, to detect the genotypes of Giardia isolates from water buffaloes in Iraq.

Methods:
A total of 180 fecal samples (82 males, 98 females) were collected from water buffaloes in the Babylon province. Microscopic method was used to determine the infection rate of Giardia intestinalis in water buffalo in the Babylon province. DNA was extracted using the fecal lysis procedure and proteinase K, Nested-PCR was used to identify the prevalence of Giardia assemblages in water buffalo, targeting the triose phosphate isomerase gene (TPI). Ten PCR-positive samples were sent for sequence analysis.

Results:
The infection rate of Giardia intestinalis was 13.88% using the conventional microscopic method and 30.55% using nested PCR in water buffalo. There was no significant difference in the prevalence of Giardia between males (29.26%) and females (31.63%). The largest infection rate was observed in buffaloes aged 1 year (34.24%), while the lowest was observed in those aged 3 years (26.66%). Phylogenetic analysis identified two genotypes of Giardia intestinalis, assemblages A and B, in Iraqi water buffaloes.

Conclusion:
The identification of Giardia intestinalis assemblages A and B in buffalo indicated that buffalo acts as a reservoir host and may be a source of zoonotic transmission.

Key words: Assemblages; Giardia intestinalis; Prevalence; TPI gene; Water buffalo.