Prevalence and molecular characterization of Giardia intestinalis isolated from children and calves in Babylon province, Iraq

BACKGROUND AND AIM: Giardia intestinalis is one of the most prevalent intestinal parasites in humans and animals, and children in close contact with livestock are particularly at risk of infection. This study aimed to detect assemblages of G. intestinalis and determine the origin of zoonotic transmission of Giardia in children and calves in different parts of Babylon province, Iraq. MATERIALS AND METHODS: One hundred stool samples from children (68 boys and 32 girls) and 100 fecal samples from calves (46 males and 54 females) of different ages were randomly collected. Molecular techniques were used to estimate the prevalence of G. intestinalis in children and calves. A nested polymerase chain reaction (PCR) was performed by targeting the triose phosphate isomerase gene in the samples to detect G. intestinalis assemblages. RESULTS: The overall rates of infection with G. intestinalis in children and calves were 21% and 34%, respectively, using the conventional microscopic method. The results illustrated that 61.90% (13/21) and 38.09% (8/21) of positive samples from children were allocated to assemblages A and B, respectively (p > 0.05). In calves, assemblages A and B were detecte in 82.35% (28/34) and 17.64% (6/34) of positive samples from calves, respectively (p ≤ 0.001). Ten PCR products were sequenced and submitted to the GenBank database. Phylogenetic analysis detected five human sequences each belonging to G. intestinalis assemblages A (OM850335–OM850339) and B (OM850340–OM850344). Similarly, five calf sequences each belonged to G. intestinalis assemblages A (ON75756–ON757660) and B (ON757661–ON757665). CONCLUSION: The detection of large numbers of G. intestinalis assemblage A in both humans and cattle indicated that cattle could be a main source of zoonotic G. intestinalis infection in children in Babylon province, Iraq.