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Experimentally induced Tyzzer's disease in the African white-tailed rat (Mystromys albicaudatus)
Abstract:
Tyzzer's disease was induced experimentally in nonimmunosuppressed, weanling Mystromys albicaudatus by oral inoculation with Bacillus piliformis spores. Focal areas of necrosis bordered by cells containing B. piliformis were observed first in the tunica muscularis of the intestine and in the periportal region of the liver 3 days post-inoculation, in the ventricular myocardium 7 days post-inoculation and in the brainstem 9 days post-inoculation. Healing in the tunica muscularis, liver and myocardium was accompanied by granuloma formation. The findings indicate that Mystromys are susceptible to B. piliformis infection. This is, to our knowledge, the first time brain lesions have been reported in any species following oral inoculation with B. piliformis. Tyzzer's disease should be considered as a possible diagnosis in Mystromys with hepatoenteritis, myocarditis, or indications of central nervous system disorders.
Insights
This study shows that Mystromys albicaudatus are susceptible to Bacillus piliformis infection, causing Tyzzer
Area of Science:
- Veterinary Pathology
- Infectious Diseases
- Comparative Pathology
Background:
- Tyzzer's disease is a significant enteric and hepatic disease affecting various animal species.
- The causative agent, Bacillus piliformis (now recognized as Clostridium piliformis), is known to cause severe gastrointestinal and liver pathology.
- Previous studies have primarily focused on immunosuppressed animals or specific species, with limited information on non-immunosuppressed models.
Purpose of the Study:
- To experimentally induce Tyzzer's disease in nonimmunosuppressed Mystromys albicaudatus (white-toothed rat).
- To characterize the pathological findings and temporal progression of Bacillus piliformis infection in this species.
- To investigate the potential for central nervous system involvement following oral inoculation.
Main Methods:
- Oral inoculation of weanling, nonimmunosuppressed Mystromys albicaudatus with Bacillus piliformis spores.
- Daily monitoring for clinical signs and necropsy at predetermined time points post-inoculation.
- Histopathological examination of tissues including the intestine, liver, myocardium, and brainstem.
Main Results:
- Focal necrosis in the tunica muscularis of the intestine and periportal liver regions observed by day 3 post-inoculation.
- Myocardial and brainstem lesions, including necrosis and inflammation, identified by days 7 and 9 post-inoculation, respectively.
- Granuloma formation observed during the healing phases in the affected tissues (intestine, liver, myocardium).
Conclusions:
- Mystromys albicaudatus are susceptible to experimental infection with Bacillus piliformis via oral inoculation.
- This study reports, for the first time, brainstem lesions in any species following oral Bacillus piliformis challenge.
- Tyzzer's disease should be considered in the differential diagnosis of Mystromys exhibiting hepatoenteritis, myocarditis, or neurological signs.