Genotypic Analysis of Giardia Duodenalis in Domestic Cats

Background:Giardia duodenalis is an intestinal flagellated protozoan that affects many mammalian species often causing severe diarrheal disease. Several different genotypes have been identified (Assemblages A‐G). Most isolates recovered from domestic cats have been assigned to either Assemblage A, the zoonotic form of the parasite, or Assemblage F, identified thus far only in cats. Genotypic variation within G. duodenalis may influence clinical presentation and course of disease. Therefore, host‐adapted genotypes may not be responsible for diarrheal disease (eg, Assemblage F in cats). Hypothesis:Multiple Giardia genotypes will be present in domestic cats, including Assemblage F, which will not be correlated with clinical signs. Animals:250 domestic cats from eastern Mississippi and northwestern Alabama. Methods:Prevalence survey. Fecal samples evaluated for cysts using a centrifugation concentration technique and a commercially available direct immunoflourescent antibody kit. Giardia isolates were characterized by PCR amplification and sequencing of the glutamate dehydrogenase gene. Results:Both Assemblage A‐I (6/17) and Assemblage F (11/17) were identified. Although Assemblage was significantly associated with age and housing, no association was detected between Assemblage and a variety of other factors including the presence of gastrointestinal signs (acute vomiting, diarrhea, and constipation). Conclusions and Clinical Importance: The presence of diarrhea in domestic cats with Giardia cannot be used as a predictor of the presence of zoonotic genotypes in animals within the study area. Although Assemblage A was associated with age and housing, veterinarians should consider any isolation of Giardia from domestic cats as potentially zoonotic.