Feline Parasitism:  Parasite Prevalence and Evaluation of New Immunoassays for Giardia and Cryptosporidium

Cats are infected with a variety of internal parasites, some of which are zoonotic. Therefore, being able to effectively detect and determine prevalence of internal parasites in cats is important for both feline and human health. Some parasites are easier to detect than others. Diagnosing Giardia duodenalis and Cryptosporidium spp. can be difficult because cysts and oocysts shed in the feces are small, shed intermittently, and require a trained technician to consistently identify them. As a result, infections with these protozoan parasites can be missed. Fecal immunoassays detect antigens in feces and can have increased sensitivity when compared to traditional microscopic techniques, but still do not detect every infection. The current reference standard is an immunoassay known as the direct immunofluorescent assay, but it requires expensive equipment and a long incubation period. As a result, two prototype lateral flow fecal immunoassays, the Cryptosporidium EZ VUE and Giardia EZ VUE, designed by TECHLAB® Inc were evaluated for the ability to detect G. duodenalis and Cryptosporidium spp. infections in cats because they are cheap, easy to use, easy to store and easy to interpret. In addition, samples were examined using a 33% zinc sulfate (ZnSO4) centrifugal fecal flotation procedure and the MERIFLUOR® Cryptosporidium/Giardia direct immunofluorescent assay (IFA), which served as the reference test. Other internal parasites found on the centrifugal fecal flotation with zinc sulfate were recorded to determine prevalence. Both EZ VUE fecal immunoassays demonstrated potential in diagnosing infections in cats when compared to centrifugal fecal flotation and the reference. Additionally, a variety of other internal parasites were identified. This included several potentially zoonotic species including Spirometra mansonoides, Ancylostoma sp. and Toxocara cati, which was also the most commonly identified species of parasite. Additionally, it was determined that several factors may contribute to higher prevalence of parasites especially in cats with the status of stray or feral.