What is pneumocystis carinii pneumonia (PCP)?
Pneumocystis carinii is a microscopic fungus that affects the lungs, and is the most important cause of pneumonia in people with HIV/Aids. People with HIV infection usually become susceptible to pneumocystis carinii pneumonia (PCP) when their CD4 cell count falls below 200/ul. In many people, this will be the first illness that marks the onset of Aids and around 80% of people with Aids will get PCP at some time. Occasionally people whose immune systems have been suppressed for reasons other than HIV infection will get PCP (e.g. people on immunosuppressive drugs after transplant, or patients receiving chemotherapy). However, the majority of cases of PCP are now seen in people with Aids. The risk of transmitting PCP from one person to another appears to be very small. It is thought that people who get PCP acquire the organism either from an environmental source, or have been carrying the organism for a while, and become ill once they are susceptible. However, there is still some debate a
