Taylor, Loni Anne Goodwin (2023-07). Giardia duodenalis and Cryptosporidium spp. Infection in the Dog (Canis lupus familiaris): A One Health Approach to Testing Strategies and Epidemiologic Analysis. Doctoral Dissertation.
Thesis
Giardia duodenalis and Cryptosporidium spp. are zoonotic protozoal pathogens, spread by a fecal-oral route, which can infect a wide range of hosts including but not limited to dogs and humans. Giardia infections were reported to be present in 15.2%, and Cryptosporidium infections in 5%, of dogs globally. The main goal of this project was to define factors associated with Giardia and Cryptosporidium in dogs in Texas. Fecal samples were collected from laboratory dogs from an academic research facility and a local laboratory dog supplier. We first assessed a human Giardia and Cryptosporidium point-of-care test in dogs. We then determined factors associated with subclinical infections in kennel housed dogs. Multilocus PCR of three gene targets was implemented, followed by sequencing and typing to determine the assemblages of G. duodenalis. SSU rRNA PCR sequencing was used to determine the species of Cryptosporidium. Finally, we assessed Giardia infection, in the State of Texas at the county level, by analyzing publicly available data on canine test positivity and potential social determinants of animal health (SDOAH). We showed that the human point of care test could successfully be used to identify Giardia and Cryptosporidium in the dog with high specificity (%) but low sensitivity (%). Giardia duodenalis assemblages A, C, and D were detected in our dogs, while C. canis was the sole species detected. We found the presence of hard feces to be associated with lower odds (0.3 [0.1, 1.0]) of subclinical Giardia infection. Dogs that were <=18 months old had 3 times the odds of subclinical Giardia infection compared to older dogs. We found that SDOAH may be indicators of canine Giardia infection risk and that counties with low veterinary coverage (represented by the veterinary care accessibility score [VCAS] <25) were also those with more Giardia infections (PR 11 [7, 18]) when college graduation rates were low. With these findings, we demonstrated the potential utility of an available point-of-care test in dogs to detect Giardia and Cryptosporidium infections and the value of understanding clinical, social, and epidemiologic risk factors of Giardia, Cryptosporidium, and other important zoonotic pathogens of public health concern.
