Felis ISSN 2398-2950

Mycobacterium lepraemurium

Synonym(s): M. lepraemurium

Contributor(s): Susan Dawson, Danielle Gunn-Moore, David Scarff




  • Family: Mycobacteriaceae.
  • Genus: Mycobacterium.
  • Species: lepraemurium.


  • Gr: myces - a fungus; bakterion - a small rod.
  • Gr: lepros - scaly; L: mur-, mus - mouse.

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Clinical Effects



  • Probably carried by rodents; no evidence of environmental reservoir.


  • Direct contact with rodents.
  • No evidence of cat-to-cat transmission.

Pathological effects

  • Immune response to M. lepraemurium varies greatly.
  • Some cats develop strong cell-mediated immunity  →  lesions containing few organisms.
  • Other cats develop incomplete immunity which destroys most organisms in tissue macrophages   →  tuberculoid form.
  • Some cats develop very poor cellular immunity  →  many infected macrophages in lesions  →   lepromatous form.
  • Incubation period 2 months to more than a year.
  • Initial focal granulomata of skin and subcutaneous tissues, usually on head, limbs and ventrum   →   spread to adjacent areas over months or years.
  • Lesions: plaques, nodules Mycobacterial infection , abscesses, ulcers and tracts.
  • Regional lymphadenopathy common.
  • Localized disease: cats usually remain otherwise healthy.
  • Rarely disseminates beyond regional lymph nodes; some cases reported with muscle, spleen, bone marrow, liver, kidney or lung involvement.
  • Disseminated disease  →  wasting, depression.
  • Tuberculoid form: poorly encapsulated accumulations of histiocytes containing few organisms, surrounded by fibrous tissue, with caseous center.
  • Lepromatous form Skin: mycobacterial infection - leprosy 01  Skin: mycobacterial infection - leprosy 02 (one-third of cases): granulomas composed of sheets of foamy macrophages containing many organisms.

Other Host Effects

  • Controversy regarding actual causative agent of feline leprosy; may not actually beM. lepraemuriumbut other closely-related acid-fast bacteria.


Control via animal

  • Wide surgical excision of lesions; may recur.
  • Usually in combination with drug therapy.

Control via chemotherapies

Control via environment

  • Avoid contact with rodents.


  • None.


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Further Reading


Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Hughes M S et al(2004) PCR studies of feline leprosy casesJ Feline Med Surg 6(4), 235-243 PubMed.
  • Malik R (2002) Feline leprosy - two different clinical syndromesJ Feline Med Surg 4, 43-59 PubMed.
  • McIntosh D W (1982Feline leprosy - a review of forty-four cases from western Canada. Can Vet J 23, 291-295.
  • Schiefer H B & Middleton D M (1983) Experimental transmission of a feline mycobacterial skin disease (feline leprosy). Vet Pathol 20, 460-471 PubMed.
  • Gunn-Moore D A & Shaw S (1997) Mycobacterial disease in the cat.In Practice19, 493-497. 
  • Arvand et al(1998) Primary isolation of Mycobacterium tuberculosis on blood agar during the diagnostic process for cat scratch diseaseInfection 26(4), 254 PubMed.
  • Hughes M S et al(1997) Determination of the etiology of presumptive feline leprosy by 16S rRNA gene analysisJ Clin Microbiol 35(10), 2464-2471 PubMed.
  • Aranaz A, Liebana E, Pickering X, Novoa C, Mateos L & Dominquez L (1996) Use of PCR in the diagnosis of TB in dogs and catsVet Rec 138, 276-280 PubMed.
  • Gunn-Moore D A, Jenkins P A & Lucke F M (1996) Feline TB; a literature review and discussion of 19 cases caused by an unusual mycobacterial variant. Vet Rec 138, 53-88 PubMed.
  • Hart C A, Becking N J & Duerden B I (1996) Tuberculosis into the next centuryJ Med Microbiol 44, 1-34.