Pneumocystis Pneumonia Causes

Pneumonia carinii is an opportunistic organism as it causes disease only under favorable conditions. When a person is immunocompromised, Pneumonia carinii proliferates and cause infection. The mechanisms involved in the growth of the organism within the alveoli are not yet understood fully. As the organism replicates, it gradually fills the alveoli. As the pneumonia progresses, fluid is accumulated and the scarring of the tissue occurs. This lowers the respiratory function and reduces the levels of oxygen in the bloodstream.

However, in individuals whose immunity is compromised due to underlying diseases like cancer, HIV/AIDS, solid organ and/or bone marrow transplantation and in individuals receiving chronic corticosteroids or other medications that affect the immune system, Pneumocystis carinii may result in infecting the lungs.

Individuals in advanced stage of AIDS have sparked a particular interest, since Pneumocystis Pneumonia (PCP) was considered as a rare infection prior to the AIDS epidemic. Up to 70% of individuals in the U.S. suffering from advanced AIDS would develop PCP, much before the use of preventive antibiotics in the treatment of PCP.

PCP in AIDS infected patients, usually develops slowly and is less severe. The symptoms include several weeks of cough, fevers, and progressive shortness of breath, associated with exertion. Patients who do not have AIDS but are suffering from PCP usually get sick faster and become severely ill.

Some patients are categorized as high-risk groups as they are at a higher risk pf contracting PCP. These groups include:

• protein malnourished patients

• patients with immunodeficiency diseases that includes severe combined immunodeficiency disease (SCID) and acquired immunodeficiency syndrome (AIDS)

• premature infants

• patients on immunosuppressive drugs (cortisone-like drugs or corticosteroids)

• AIDS is the most common risk factor for developing PCP in the U.S. However, PCP is also found in countries where there is widespread hunger and poor hygiene.