Recently, a Giardia vaccine has become commercially available in the USA fo
r prevention of clinical signs of giardiasis and reduction of cyst shedding
in dogs and cats. The vaccine is based upon the current state of knowledge
of Giardia antigenicity and immunology. Here, Merle Olson, Howard Ceri and
Douglas Morck describe studies that led to the development of this vaccine
and subsequent efficacy studies. Immunoprophylaxis and immunotherapeutic a
pplication of the vaccine are discussed.