Molecular detection and zoonotic potential of Cryptosporidium spp. and Giardia duodenalis in cats and dogs from metropolitan areas of Bangladesh.

Cryptosporidium spp. and Giardia duodenalis are intestinal protozoan parasites of zoonotic concern that cause gastrointestinal diseases in humans and various animals, including cats and dogs. This study investigates the prevalence, risk factors, and genetic diversity of Cryptosporidium spp. and G. duodenalis in domestic cats and dogs in Bangladesh to assess their zoonotic potential. Fecal samples were collected from 197 cats and 120 dogs in Dhaka and Gazipur metropolitan areas. We performed nested PCR targeting the small subunit ribosomal RNA (SSU rRNA) gene for Cryptosporidium and the β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes for G. duodenalis, followed by nucleotide sequencing and analysis. The overall prevalence of Cryptosporidium was 8.1 % in cats and 4.2 % in dogs, whereas G. duodenalis was more common, detected in 29.9 % of cats and 25 % of dogs. Among examined variables, only sex and food types were significantly associated with G. duodenalis infection in dogs and cats, respectively. Molecular analysis identified three Cryptosporidium spp. in cats, including C. felis (81.3 %), C. baileyi (12.5 %), and C. canis (6.3 %), whereas 100 % of Cryptosporidium isolates from dogs were identified as C. canis. Multilocus genotyping of G. duodenalis revealed both host-adapted and zoonotic assemblages. Assemblage A predominated in both cats and dogs, followed by F and C in cats and C and D in dogs, with mixed infections observed in both hosts. The detection of zoonotic species and assemblages underscores the potential role of cats and dogs as reservoirs for human infection. These findings highlight the importance of monitoring intestinal protozoa in companion animals and promoting appropriate hygiene practices within a One Health framework.