Characterization of Giardia duodenalis infections in dogs in Trinidad and Tobago

To our knowledge, the zoonotic potential of Giardia duodenalis has not been assessed in companion animals in Trinidad and Tobago. This report details the first attempt to evaluate the potential zoonotic risk of G. duodenalis in dogs and identify assemblages of G. duodenalis found in dog populations on both islands. Fecal samples were collected from free-roaming dogs and dogs at the Trinidad and Tobago Society for the Prevention of Cruelty to Animals from October 2010 to June 2011. A total of 168 samples were collected of which 104 samples were analyzed for the presence of G. duodenalis by PCR amplification of the ssu-rRNA gene with subsequent assemblage-typing. A subset of samples was also analyzed by ELISA. Twenty-six samples were positive for G. duodenalis by PCR for an overall prevalence of 25%. Four samples were identified as assemblage C (15.4%), 21 as assemblage D (80.8%), and one as assemblage E (3.8%). Puppies were four-times more likely to be infected with G. duodenalis than adult dogs (OR 4.61, 95% CI 1.73-12.2). There was a significant agreement between ELISA and PCR in the detection of the protozoa (κ = 0.67). We infer from our results that while the prevalence of G. duodenalis is relatively high in Trinidad and Tobago, the zoonotic risk of infection in humans is low since neither assemblage A nor B was identified in the study population.