Prevalence of Giardia duodenalis genetic assemblages isolated from dogs and cats in Poland.

Introduction: Giardia duodenalis (syn. G. intestinalis and G. lamblia) is a protozoan intestinal parasite that infects various vertebrates. Genetic analyses of G. duodenalis have identified eight genetic assemblages (groups), designated A-H. This study aimed to determine the prevalence of G. duodenalis in household dogs and cats in Poland, analyse isolates by assemblage and relate assemblage results to zoonotic potential. Material and Methods: From January to February 2024, 1,937 faecal samples from dogs and 1,077 samples from cats were examined microscopically for G. duodenalis cysts using the zinc flotation method. Positive samples were retained for further molecular tests. Genetic analysis was performed on the basis of the β-giardin locus which is 511 base pairs long. The obtained sequences were compared with reference sequences in the GenBank database. Results: Giardia duodenalis cysts were detected in 11.3% (219/1,937) of dogs and 7.06% (76/1,077) of cats using the zinc flotation method. Assemblages B, C, D and F were identified in 11, 77, 126 and 5 dogs, respectively. All isolates from cats were identified as assemblage F. Conclusion: The high rate of infection in pets increases the risk of transmission of zoonotic Giardia genetic assemblages to humans.