Introduction

Classification

Taxonomy

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

Etymology

• Greek: pneuma - wind, spirit, air; kustis - bladder.
• Latin: carina - keel, ridge.

Active Forms

Clinical Effects

Epidemiology

Habitat

• Main habitat - mammalian respiratory tract.

Lifecycle

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

Transmission

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

Pathological effects

• Majority disease seen in immunocompromised patients, eg human AIDS patients.

• Usually confined to lung; pneumonia associated with large numbers P. carinii in alveolar spaces.
• Interstitial pneumonia associated with large numbers of P. carinii organisms in alveolar spaces.

Other Host Effects

• Most infections latent or subclinical.

Control

Control via chemotherapies

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

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Masur H (1992) Prevention and treatment of pneumocystis pneumonia. New England J Med 327 (26), 1853-1860 PubMed.
• Farrow B R, Watson A D, Hartley W J et al (1972) Pneumocystis pneumonia in the dog. J Comparative Pathology 82 (4), 447-453 PubMed.

Other sources of information

• Greene C E and Chandler F W (1990) Pneumocystosis. In: Infectious diseases of the Dog and Cat. Ed: C E Greene. Philadelphia: W B Saunders. pp 854-61.