Prevalence and genotypes of Giardia lamblia from stray dogs and cats in Guangdong, China

Giardia lamblia is a worldwide zoonotic intestinal parasite that infects humans and a wide range of mammals including dogs and cats, causing giardiasis with diarrhea. To investigate the infection and distribution of G. lamblia genotypes from stray dogs and cats in Guangdong, China according to different districts, gender and ages, fecal samples were collected and examined by microscopy, and all isolates were genotyped by PCR amplification using beta-giardin (bg) and triose phosphate isomerase (tpi) genes as molecular markers. The results showed that the prevalence of dogs and cats was 10.8% (57/527) and 5.8% (6/104), respectively. Sixty-one samples were detected by microscopy and 63 were amplified and successfully sequenced by the PCR. Based on the phylogenetic analysis, 25 canine isolates (24 assemblages AI and 1 assemblage D) were genotyped by tpi gene and 57 canine isolates (26 assemblages AI, 18 assemblages C and 13 assemblages D) genotyped by bg gene; 6 feline isolates were identified as assemblage AI by tpi gene, and as 3 assemblages AI and 3 assemblages F by bg gene. The dominant genotypes were assemblage AI in younger dogs (assemblage C in adult dogs) and assemblage C in male dogs (assemblage AI in female dogs). Mixed genotype infections were found in different age and gender groups. The results indicated that G. lamblia from stray dogs and cats in Guangdong province had a zoonotic potential with assemblage AI as the prevalent genotype. The different risk factors (age and sex) may have an impact on the infection of different genotypes.