By Sarah Weivoda & Kaleb Hale This is a smear of P. Carinii isolated from human lung tissue.  Pathogen responsible for Causing interstitial plasma cell pneumonitis, which leads to Pneumocystis carinii pneumnia

Taxonomic Considerations Currently considered to be a fungus -Based on nucleic acid analysis Previously considered to be a protozoa Domain: Eukaryota Kingdom: Fungi Phylum: Ascomycota Class: Pneumocystidomycetes Order: Pneumocystidales Family: Pneumocystidaceae Genus: Pneumocystis Species: carinii

History of P. Carinii First discovered in 1909 by Carlos Chagas Found to be associated with clinical pneumonia shortly after World War 2 Until the 1980’s it occurred very rarely and only caused pneumonia in people with congenital immunodeficiency's and patients immunocompromised by cancer. From the 1980’s on the incidence of Pneumocystis Carinii associated pneumonia significantly increased due to the AIDS epidemic. P. Carinii is now the leading cause of death by opportunistic infection in AIDS patients.

Geographic range Affects Humans and animals world wide Infects a broad range of mammalian species including: -Humans -Mice -Rats -Cats -Dogs -Pigs -Most healthy children have been exposed to P. Carinii by age 3 to 4 -Primarily affects immunocompromised individuals

Definitive Host Immunocompromised Humans and many other mammalians such as mice, rats, cats, dogs and pigs. P. Carinii has no known intermediate host or vector species

Pathogenesis The specific mode of transmission is unknown but evidence suggest airborne transmission. Causes disease by growing and filling the alveoli of the lungs

Clinical Signs Physical Symptoms Initial *Fever *Fatigue *Weight Loss Dyspnea Tachypnea Nonproductive cough Fevers Chills Sweats Progressive, profound fatigue Cyanosis around the mouth, hands, feet, or mucous membranes Progressive Extrapulmonary manifestations Death

Laboratory Diagnosis Trophozoite Cyst

Morphology and Biology  P. Carinii goes through 3 morphological stages: 1. Trophozoite - pleomorphic in shape - Ranges from 1 to 5 µm in diameter - Has small filopodia 2. Precyst - Oval in shape - Has few filopodia - Has a cluster of mitochondria in its center 3. Cyst - Spherical in shape - Has a thick membrane made of chitin - Contains 8 intracystic bodies All morphological stages can be found within the lungs of the infected individual

Life Cycle

Treatment Drug of choice Trimethoprim-sulfamethoxazole Recommended others Pentamidine Trimethoprim plus daposone Atovaquone Primaquine plus clindamycin

References ids.html ids.html overview overview htm htm Roberts, L. Janovy, J. Foundations of Parasitology, 8 th ed. New York: McGraw-Hill, 2009.