Pneumocystis Pneumonia (PCP): A Fungal Infection of Weakened Immune Systems

Pneumocystis jirovecii is a fungus found all over the world. Many people are exposed to it as children, and some carry it in their lungs. In healthy people it usually causes no illness — but it can make people with weakened immune systems sick, including those who:

• have HIV;
• have an autoimmune disease;
• have cancer;
• have a chronic lung disease;
• have had an organ or bone marrow transplant;
• take medicines that weaken the immune system, such as chemotherapy or steroids.

How it spreads

Pneumocystis spreads from person to person through the air — and people can pass it on even when it isn't making them sick.

Pneumocystis pneumonia

The most common illness it causes is pneumocystis pneumonia (PCP). Pneumonia is an infection of one or both lungs in which the air sacs fill with fluid or pus.

Symptoms can develop over several days or weeks and may include:

• fever and chills;
• cough;
• trouble breathing;
• chest pain;
• fatigue.

PCP can be life-threatening, so early treatment matters. Contact your health care provider if you have symptoms you think could be PCP.

Diagnosis

Your provider will take a sample of fluid or tissue from your lungs — coughed-up mucus (sputum), fluid collected during a bronchoalveolar lavage, or tissue from a biopsy — and send it to a lab to test for Pneumocystis.

Treatment

PCP is treated with antibiotics, by mouth or through an IV, for about 3 weeks. Severe cases may need hospital care.

Prevention

There is no vaccine. Some people at high risk may need to take antibiotics to prevent PCP.

Sources

Based on "Pneumocystis Infections," MedlinePlus, U.S. National Library of Medicine, drawing on the Centers for Disease Control and Prevention; a work of the United States government in the public domain.