Tyzzer's disease
Tyzzer's disease is an acute epizootic bacterial disease found in rodents, rabbits, dogs, cats, birds, pandas, deer, foals, cattle, and other mammals including gerbils and spinifex hopping-mice. It is caused by the spore-forming bacterium Clostridium piliforme, formerly known as Bacillus piliformis. It is an infectious disease characterized by necrotic lesions on the liver, is usually fatal, and is present worldwide. Animals with the disease become infected through oral ingestion of the bacterial spores and usually die within a matter of days. Animals most commonly affected include young, stressed animals in laboratory environments, such as immature rodents and rabbits. Most commonly affected wild animals include muskrats ' and occasionally cottontail rabbits '. Even today, much remains unknown about Tyzzer's disease, including how and why it occurs.
Distribution
Although Tyzzer's disease is commonly found in laboratory animals worldwide, infected wild animal populations have been identified in North America and Australia. Specific locations where the disease has been reported in the United States include Connecticut, Idaho, Iowa, Maryland, Michigan, Montana, Ohio, Wisconsin, and Wyoming. In Canada, it has been reported in British Columbia, Manitoba, Ontario, and Saskatchewan. Outbreaks in these locations are primarily attributed to muskrat populations; however infected cottontail rabbits have been discovered in Maryland.Transmission
Tyzzer's disease is transmitted horizontally through the fecal-oral route. Bacterial spores within infected fecal matter can contaminate soil or feed and become orally ingested by a viable host. Success of the disease is determined by the amount and virulence of the bacteria and the resistance of the host. Laboratory animals are more susceptible to this disease, as bacteria spores from infected feces can survive in bedding at room temperature for over one year. Animals do occasionally transfer the disease asymptomatically, acting as carriers. Infected animals are more likely to develop the disease when subjected to stressful conditions.Clinical Signs
Common clinical signs of Tyzzer's Disease include watery diarrhea, depression, emaciation, and a ruffled coat. Other observed clinical signs include melena, depression, lethargy, and decreased temperature. In muskrats, this disease is characterized by extensive hemorrhaging within the lower intestine and abdomen. Due to the fast-acting nature of this disease, infected individuals often do not live long enough to exhibit symptoms. It is not uncommon for an infected animal to die within 1–10 days of disease contraction.During necropsy, inflammation of the ileum, cecum, and colon are commonly present. Perhaps the most distinctive trait of this disease, however, is the grayish yellow necrotic lesions found on the liver of diseased animals. The number of these spots present can range from one to countless. Occasionally, lesions are discovered in the lower intestinal tract and heart as well. Even with physical signs and symptoms present, a conclusive diagnosis is dependent upon the presence of C. piliforme within the liver of the infected animal.