Tyzzer’s Disease

Etiology:  Clostridium piliforme is a Gram-negative, pleomorphic, obligate intracellular bacteria that produces spores.

Incidence:  The incidence of spontaneous disease is quite low, occurring in sporadic outbreaks.

Transmission:  Infection occurs by contact with infected animals or bedding, via the fecal-oral route.  Unlike most other rodents and rabbits, gerbils are innately susceptible to expressing overt Tyzzer’s disease without physiologic stress or steroid therapy to aid in disease development.

Clinical Signs:  This is an acute, usually fatal, enterohepatic disease in gerbils.  In colony situations, high mortality rates can occur with some animals exhibiting depression, unthrifty appearance, and varying degrees of watery diarrhea.  Morbidity and mortality are highest in young gerbils and pregnant females, although all age groups can be affected.

Pathology:  Grossly, multiple white foci of necrosis in the liver with mild to moderate enteritis (A.), serosal edema, and possible brain and cardiac involvement may all appear in affected animals.  Coagulative liver necrosis with minimal inflammatory cell infiltrate is observed on histopathologic examination of the liver (arrowheads, B.).

Diagnosis:  Definitive diagnosis is made by demonstration of the organism in hepatocytes surrounding necrotic foci of the liver or intestine sections stained by silver (arrowheads, C.). Infection can also be diagnosed by PCR of feces or tissue and serology using MFI or IFA.