Nomenclature and genetic groupings of Giardia infecting mammals

Giardia is a ubiquitous and well-known enteric parasite affecting humans an d a range of domestic and wild mammals. It is one of the most common parasi tes of domestic dogs and dairy cattle and a frequently recognized waterborn e pathogen. Giardiasis is considered to be a re-emerging infection because of its association with outbreaks of diarrhoea in child-care centres. Altho ugh only a single species has been recognized as causing disease in humans and most other mammals, molecular characterization of morphologically ident ical isolates from humans and numerous other species of mammals has confirm ed the heterogeneity of this parasite and provided a basis for a clearer un derstanding of the taxonomy and zoonotic potential of Giardia.