Etiology: Spironucleus muris is a flagellated protozoan.

Incidence:  The incidence of infection is low in conventional gerbil colonies.

Transmission:  Ingestion of infective cysts passed in fecal material is the primary mode of transmission.

Distribution:  Found primarily in the crypts of the duodenum and pyloric glands. In young animals, luminal protozoa are more numerous.

Clinical Signs:  Clinical signs are not usually observed.

Diagnosis:  Direct smears of small intestinal contents reveal fast darting protozoa.  Fecal PCR may also be used.

Diagnostic Morphology:  Trophozoite: 7- 9 x 2- 3 µm, piriform (teardrop)-shaped or carrot-shaped, with 6 anterior flagella, 2 posterior flagella, 2 anterior nuclei and 2 separate axostyles.