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Submitted to: American Association of Veterinary Parasitologists
Publication Type: Proceedings Publication Acceptance Date: 5/19/2008 Publication Date: 7/22/2008 Citation: Santin, M. 2008. Overview of the epidemiology of Giardia. American Association of Veterinary Parasitologists 53rd Annual Conference, July 19-22, 2009, New Orleans, LA. p.81-82. Interpretive Summary: Technical Abstract: Of all species of Giardia, only G. duodenalis infects humans, livestock, companion animals, and wildlife. The similar morphology within G. duodenalis masks genetic and biotypic differences that are large enough for G. duodenalis now to be considered a species complex. Within the G. duodenalis complex there are 7 assemblages (genotypes) designated A through G. Assemblages A and B have the widest host range infecting humans, companion animals, livestock, and wildlife. Assemblages C and D have been found to infect only canids. Assemblage E has been found to infect only livestock; Assemblages F and G infect only cats and rats, respectively. The taxonomy of Giardia remains controversial and the epidemiology of different assemblages is unclear. Little epidemiologic evidence exists that strongly supports the importance of zoonotic transmission of giardiasis to humans. The complex epidemiology of giardiasis is further complicated by the difficulties in using conventional criteria, such us differences in cyst morphology, to distinguish the assemblages that are human pathogens from those that are not. However, the implementation of newer molecular tools should help to clarify Giardia diversity and improve our understanding of this parasite. Before more definitive conclusions can be made, further molecular epidemiologic studies of giardiasis in humans and animals are needed since these studies will help to determine whether human infections result from anthroponotic or zoonotic transmission. |
