Felis ISSN 2398-2950

Pneumocystis carinii

Synonym(s): P. carinii

Contributor(s): Ibulaimu Kakoma, Grace Mulcahy




  • Phylum: Sarcomastigophora.
  • Subphylum: Sarcodina.
  • Genus: Pneumocystis.

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Clinical Effects



  • Main habitat - mammalian respiratory tract.


  • Direct lifecycle.
  • Evaluation of RNA sequences suggest that P. carinii may be more closely related to fungi than protozoa.
  • Multiplies in lungs when host becomes immunosuppressed.


  • Usually from infected to susceptible animal within species.
  • Infected aerosol.

Pathological effects

  • Majority disease seen in immunocompromized patients, eg human HIV/AIDS patients.
  • Usually confined to lung; pneumonia associated with large numbers P. carinii in alveolar spaces.

Other Host Effects

  • Most infections latent or subclinical.


Control via chemotherapies

  • Trimethroprim-sulfonamide Trimethoprim.
  • Pentamidine is used as a prophylactic aerosol in human beings.


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Further Reading


Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Lacroix C et al (1996) Co-infection of Toxoplasma gondii with other pathogens - pathogenicity and chemotherapy in animal models. Curr Top Microbiol Immunol 219, 223-233.
  • Yuezhong Y et al(1996) Pneumonia in cats caused by Pneumocystis carinii purified from mouse lungs. Vet Parasitol 1(1-2), 171-175.
  • Hong S T et al(1992) Susceptibility of various animals to Pneumocystis carinii infection. Kisaengchunhak Chapchi 30(4), 277-281.
  • Masur H (1992) Prevention and treatment of pneumocystosis. New Eng J Med 327, 1853.
  • Shiota T et al(1990) Pneumocystis carinii infection in corticosteroid-treated cats. J Parasitol 76(3), 441-445.
  • Foreyt W J (1989) Diagnostic parasitology. Vet Clin North Am Small Anim Pract 19(5), 979-1000.
  • Hagler D N et al(1987) Feline leukaemia virus and Pneumocystis carinii infection. J Parasitol 73(6), 1284-1286.
  • Settnes O P et al(1984) Occurrence of Pneumocystis carinii Delanoe and Delanoe, 1912 in dogs and cats in Denmark. Nord Vet Med 36(5-6), 179-181.

Other sources of information

  • Greene C E & Chandler F W (1990) Pneumocystosis. In: Infectious diseases of the Dog and Cat. Ed: Greene C E, Philadephia: W B Saunders. pp 854-861.