Diseases / List of Bacterial Diseases / Disease description:

Tyzzer's Disease in Lagomorphs 

INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

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General and References

Disease Summary

Tyzzer's disease usually causes profuse diarrhoea and rapid death and may be seen in many species including mice, gerbils, hamsters, rats, rabbits, cats and rhesus monkeys. Lesions are most commonly seen in the caecum and liver. (B614.8.w8)
Lagomorphs
  • Tyzzer's disease was first recognised in rabbits in 1965 and is reportedly widespread in rabbit colonies. (B614.8.w8)

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Alternative Names (Synonyms)

  • Clostridium piliforme infection
  • Bacillus piliformis infection 

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Disease Type

Bacterial Infection

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Infectious/Non-Infectious Agent associated with the Disease

Clostridium piliformis
  • This is a large pleomorphic, gram-negative, motile, spore-forming, obligate, intracellular bacterium. (B600.10.w10, B601.8.w8, B614.8.w8, J29.9.w1)
  • Synonym: Bacillus piliformis was the original name for Clostridium piliforme before the bacterium was reclassified based on the molecular studies of the genome. (B600.10.w10)
  • Aetiology: spores are shed in the faeces and then infection occurs when the animal ingests contaminated material. The organism is thought to initially reside latently in the intestinal tract and then immunosuppressant or stress can precipitate overt disease possibly by facilitating the invasion of the intestinal mucosa and the systemic spread of the bacteria. Infection of the heart occurs by way of the lymphatics whereas infection of the liver occurs via the portal circulation. (B600.10.w10, B614.8.w8)
  • Spores remain infectious in the environment for a long time (J29.9.w1); more than a year. (B600.10.w10)

Infective "Taxa"

  • Clostridium piliforme

Non-infective agents

--

Physical agents

Indirect / Secondary

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References

Disease Author

Nikki Fox BVSc MRCVS (V.w103)
Click image for main Reference Section

Referees

William Lewis BVSc CertZooMed MRCVS (V.w129); Richard Saunders BVSc BSc CertZooMed MRCVS (V.w121)

Major References / Reviews

Code and Title List

B209.28.w28l, B600.10.w10, B601.8.w8, B614.8.w8, J29.9.w1

Other References

Code and Title List

 

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General Tyzzer's disease causes a focal hepatitis and enteritis. (B614.8.w8)

Clinical Characteristics

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Lagomorphs
  • Acute onset, short course of one to four days. (J29.9.w1)
  • Profuse watery diarrhoea (B600.10.w10, B614.8.w8, J29.9.w1)
  • Faecal staining around the perineum (B600.10.w10, B614.8.w8)
  • Listlessness/depression. (B614.8.w8, J29.9.w1)
  • Dehydration (B600.10.w10, B614.8.w8, J29.9.w1)
  • Anorexia (B614.8.w8)
  • Death (B600.10.w10). 
    • Death occurs within one to two days of the onset of clinical signs and occurs in around 90% of affected rabbits. (B614.8.w8)
  • If rabbits survive the acute infection, they may sometimes develop chronic disease (with small intestinal fibrosis and stenosis); progressive weight loss and ill thrift may be seen. (B601.8.w8, B614.8.w8)

In Sylvilagus floridanus - Eastern Cottontail

  • Dysentery is reported to occur in affected cottontails (Sylvilagus floridanus - Eastern Cottontail). (B209.28.w28l)
  • In experimentally infected Sylvilagus floridanus - Eastern Cottontail, unformed, tarry stools were passed after three days, the perianal fur was soiled with tarry faeces, and the rabbits died (or were euthanized while moribund) after 4 - 6 days. (J1.12.w14)
    • Greater quantities of unformed stools were passed, and death was sooner, in rabbits treated with corticosteroids at the same time as intragastric inoculation of bacilli. (J1.12.w14)

Incubation

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Lagomorphs

Mortality / Morbidity

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Lagomorphs
  • HIgh morbidity and mortality, particulary in weanling rabbits. (J29.9.w1)
  • This disease usually occurs epizootically in rabbits but may also occur enzootically with large numbers of subclinically infected rabbits and only sporadic clinical cases. (B614.8.w8)
  • Mortality rate: may approach 50 % at the peak of an outbreak. (B614.8.w8)
  • In Sylvilagus floridanus - Eastern Cottontail, experimentally infected with 103.8 ELD50 bacilli intragastrically, all four infected rabbits died. (J1.12.w14)

Pathology

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Lagomorphs
Gross pathology
  • General: 
    • Perineal faecal soiling and dehydration. (B614.8.w8)
  • Gastrointestinal tract: 
    • Intestinal wall oedema. (B601.8.w8)
    • Necrotic lesions in the caecum and the adjacent intestine. (B614.8.w8, J29.9.w1)
    • In the caecum there may be ecchymotic and petechial haemorrhages on the serosal surface; thickened and oedematous wall; patchy areas of necrosis in the mucosa. (B614.8.w8)
    • The lesions that are seen in the caecum frequently extend to the adjacent proximal colon and distal ileum. (B209.28.w28l, B614.8.w8)
    • The intestinal contents may be fluid. (B209.28.w28l)
    • In chronic cases stenosis of the intestine due to fibrosis at the areas of previous necrosis. (B600.10.w10, B601.8.w8, B614.8.w8)
  • Liver:
    • Necrotic lesions are seen in the liver; however these lesions may be absent in peracute cases. (B614.8.w8)
      • Numerous pinpoint white foci approximately 2 to 3 mm (or less) in diameter throughout the parenchyma. (B209.28.w28l, B614.8.w8)
  • Heart: 
    • This organ is frequently spared but necrotic lesions may be present and seen as white streaks of pale foci most commonly in the left ventricle and the septum. (B614.8.w8, J29.9.w1)
      • Myocardial lesions are not found in peracute disease. (B600.10.w10)
  • In Sylvilagus floridanus - Eastern Cottontail, experimentally infected with 103.8 ELD50 bacilli intragastrically. (J1.12.w14)
    • Perineal fur soiled with tarry faeces.
    • Increased, straw-coloured peritoneal fluid.
    • GIT: Terminal 15 cm of the ileum, plus the caecum and colon, showed conspicuous ulceration of the mucosa. 
    • Hepatic: few miliary white spots.
    • Cardiac: in one individual (the longest survivor), a 1 x 5 mm white band in the left ventricular myocardium.
Histopathology
  • Gastrointestinal tract: 
    • Haemorrhages in the caecal submucosa. (B209.28.w28l, B614.8.w8)
    • Submucosal oedema and mucosal necrosis in the caecum and the adjacent intestine. (B209.28.w28l, B614.8.w8)
    • Mucosal necrosis may sometimes spread into the submucosa and the muscularis. (B614.8.w8)
    • Clostridial piliformis organisms may be seen in the epithelial and muscle cells. (B209.28.w28l)
  • Liver:
    • Focal necrotic areas which are usually close to the portal areas. (B209.28.w28l; B614.8.w8)
    • Polymorphonuclear leucocytes may surround the necrotic foci and they may also be seen in the hepatic sinusoids. (B614.8.w8)
    • Chronic lesions may be calcified and surrounded by fibrosis and multinucleated giant cells. (B209.28.w28l; B614.8.w8)
    • Clostridiaum piliforme organisms may be seen in intact hepatocytes at the edge of the acute lesions. However, they may be absent in chronic lesions. (B209.28.w28l, B614.8.w8)
      • Using the Warthin-Starry stain, the bacteria are seen as light brown to black rods. (B614.8.w8)
  • Heart:
    • Linear or focal areas of necrosis close to myocardial blood vessels. There is sometimes a moderate inflammatory cell response in association with these necrotic areas. (B614.8.w8)
      • Myocardial lesions generally occur in the left ventricle and septum. (B600.10.w10)
      • Myocardial lesions are not found in peracute disease. (B600.10.w10)
  • In Sylvilagus floridanus - Eastern Cottontail, experimentally infected with 103.8 ELD50 bacilli intragastrically, all four infected rabbits died. (J1.12.w14)
    • GIT: lower GIT, focal necrosis epithelial cells.
    • Hepatic: focal necrosis of hepatocytes.
    • Cardiac: occasional necrosis of myocardial cells.

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Human Health Considerations

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Susceptibility / Transmission

General information on Susceptibility / Transmission

  • Transmission occurs via the faecal oral route. 
  • In rodents, transplacental transmission has also been reported. (B614.8.w8)
Lagomorphs Susceptibility
  • Young rabbits are most susceptible with a particularly high mortality rate reported in six- to twelve-week-old rabbits. However, the disease may also occur in younger rabbits and adults. (B614.8.w8)
    • Six to eight week old weanling rabbits are the most susceptible to this disease. (B600.10.w10)
    • Predisposing factors include:
      • Overcrowding (B600.10.w10)
      • Poor husbandry (B600.10.w10)
      • Inappropriate diet (B600.10.w10)
      • Immunosuppression. (B600.10.w10, B614.8.w8, J1.12.w14)
      • Stress (B614.8.w8)

Transmission

  • Faecal oral route: spores are shed in the faeces and then infection occurs when the rabbit ingests contaminated material. (B614.8.w8, J29.9.w1)
    • In pet rabbits, mainly from contamination of food by wild rodents. (B601.8.w8)
  • Transplacentally: transplacental transmission has been reported in rodents and it is possible that this may occur in rabbits as well. (B614.8.w8)

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Disease has been reported in either the wild or in captivity in:

Lagomorphs:

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" volume has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

(List does not contain all other species groups affected by this disease)

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Disease has been specifically reported in Free-ranging populations of:

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" volume has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

(List does not contain all other species groups affected by this disease)

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality

  • The vegetative form of Clostridium piliformis is unstable outside the host. (B614.8.w8)
  • Spores will be killed by heating them at 80 C for thirty minutes. (B614.8.w8)

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Regions / Countries where the Infectious Agent or Disease has been recorded

  • Seen in rabbits in Japan, USA. (B600.10.w10, B614.8.w8, J1.12.w14)

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

  • --

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis

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Lagomorphs
  • Presumptive diagnosis
    • Typical gross and microscopic lesions. (B614.8.w8)
      • Intestinal wall oedema is characteristic. (B601.8.w8)
    • Organisms are visible on histopathological examination of the liver. (B600.10.w10)
  • Definitive diagnosis: 
    • Demonstration of characteristic intra-cellular bacteria in the affected tissues via histopathology. The tissue needs to be prepared with special stains: the Warthin-Starry silver stain is the most effective but Giemsa or periodic acid-schiff stains can also be used. Immunofluorescence can be useful in identifying the organisms if they are not evident in the specially stained preparations. (B614.8.w8)
Related Techniques
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Similar Diseases (Differential Diagnosis)

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Lagomorphs
  • Similar clinical signs and lesions to those seen with Tyzzer's disease in rabbits have been seen in laboratory rabbits in which Escherichia coli was the only bacterium found (Colibacillosis). (J240.37.w1)

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Treatment and Control

Specific Medical Treatment

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Lagomorphs

"There is no treatment known to be of value for clinically ill rabbits". (B614.8.w8)

  • Antibiotic treatment yields poor results possibly due to the intracellular location of the organism limiting the efficacy of the medication. (B614.8.w8)
  • Chlortetracycline, streptomycin, penicillin and erythromycin were shown to be only partially inhibitory of the growth of this organism in embryonated eggs, and sulfamethazine and chloramphenicol were reported to be completely lacking in inhibitory properties. (B614.8.w8)
  • Oxytetracycline 50 mg/kg orally every 12 hours may assist in suppressing an outbreak. (J29.9.w1)
  • Although antibiotics are not effective in clinical cases, anecdotal evidence suggests antibiotics may be of value in limiting the epizootics: 
    • In one outbreak of Tyzzer's disease, oxytetracycline was used in the drinking water and the epizootic ended in thirty six hours (1971). (B614.8.w8)
    • In another case, clinical disease was reported to be eliminated from a mouse colony after tetracycline was added to the drinking water. (B614.8.w8)
Related Techniques

 

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General Nursing and Surgical Techniques

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Lagomorphs Fluid therapy. (J29.9.w1)
Related Techniques
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Preventative Measures

Vaccination --
Lagomorphs There is no vaccine available for this disease. (B614.8.w8)
Prophylactic Treatment

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Lagomorphs --
Related Techniques
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Environmental and Population Control Measures

General Environment Changes, Cleaning and Disinfection Prevention depends mainly on good husbandry. (B614.8.w8)

Lagomorphs

Good hygiene. (J29.9.w1)

Reduce exposure of the animals to spores by:

  • Regular cage cleaning. (B614.8.w8)
  • Prevention of crowding. (B614.8.w8)
  • Dust control (B614.8.w8)

Inactivate spores by:

  • 0.3% sodium hypochlorite solution. (B614.8.w8, J29.9.w1) or
  • Heating to 80 C for thirty minutes. (B614.8.w8)
Population Control Measures --
Lagomorphs Remove sick animals and minimise stress to reduce the likelihood of disease outbreaks. (B614.8.w8, J29.9.w1)
Isolation, Quarantine and Screening --
Lagomorphs
  • Screening for serum antibodies against this organism can be a useful means of rabbit colony surveillance. Subclinically infected animals will produce antibodies which persist for long periods, possibly throughout life. Indirect fluorescent antibody assay or the enzyme-linked immunosuppressant assays can be used for detection of antibodies. (B614.8.w8)
  • Animals testing positive should be removed. (B614.8.w8)
Related Techniques
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