Opportunistic Infection: Pneumocystis
An opportunistic infection is an infection caused by a virus, bacteria, or fungus when a person’s natural immune defenses are compromised. Usually infections by these pathogens do not arise in healthy individuals. The pathogens require an “opportunity” (i.e. weakened immune system) to replicate and, thus, infect the host.
Pneumocystis causes life-threatening opportunistic infections in patients suffering from advanced HIV infections, hematological malignancies, and genetic immune deficiencies, those undergoing transplant of solid organ, bone marrow, and stem cells, and those being treated for cancer and auto-immune disorders. The infection typically presents itself as a respiratory infection called Pneumocystis pneumonia (PCP). PCP is the most common opportunistic infection in HIV/AIDS patients. It is estimated that approximately 20% of all HIV/AIDS patients are at risk for PCP infection and approximately 15 - 20% of those patients die from the pneumonia. Estimates in other immunocompromised patients indicate that approximately 10% are at risk for PCP infection and mortality rates are similar to HIV/AIDS.