Etiology: Giardia muris is a flagellated, one celled, eukaryotic organism.

Incidence: Incidence of infection is common.

Transmission: Fecal-oral transmission occurs via ingestion of infective cysts.

Distribution: Giardia muris is found in the anterior small intestine.

Clinical signs: Clinical signs are not usually observed. These protozoa may proliferate in diarrheic states, however their role as contributors to disease is poorly defined.

Diagnosis:

Antemortem: PCR of feces can be used to diagnose infection.  Wet mounts of fresh fecal material or use of sucrose gradient may reveal cyst forms (this method of diagnosis is difficult).

Postmortem: Wet mounts of intestinal contents may reveal slow-moving flagellated protozoa with a “falling leaf” rolling motility. Histopathologic examination may also be used to diagnose Giardia species infection.

Diagnostic morphology: Broad, piriform trophozoite with 2 anterior nuclei that when stained with weak iodine solution gives the appearance of a “monkey face.” There are eight caudally directed flagella.