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Pneumocystis jiroveci pneumonia


Pneumocystis jiroveci pneumonia is a fungal infection of the lungs. The disease used to be called Pneumocystis carini or PCP pneumonia.

Alternative Names

Pneumocystosis; PCP; Pneumocystis carinii


This type of pneumonia is caused by the fungus Pneumocystis jiroveci. This fungus is common in the environment and rarely causes illness in healthy people.

However, it can cause a lung infection in people with a weakened immune system due to:

  • Cancer
  • Chronic use of corticosteroids or other medications that weaken the immune system
  • Organ or bone marrow transplant

Pneumocystis jiroveci was a relatively rare infection before the AIDS epidemic. Before the use of preventive antibiotics for the condition, most people in the United States with advanced AIDS would develop this infection.


Pneumocystis pneumonia in those with AIDS usually develops slowly over days to weeks or even months, and is less severe. People with pneumocystis pneumonia who do not have AIDS usually get sick faster and are more acutely ill.

Symptoms include:

  • Cough, often mild and dry
  • Fever
  • Rapid breathing
  • Shortness of breath, especially with activity (exertion)

Exams and Tests


Antibiotics can be given by mouth (orally) or through a vein (intravenously), depending on the severity of the illness.

People with low oxygen levels and moderate to severe disease are often prescribed corticosteroids as well.

Outlook (Prognosis)

Pneumocystis pneumonia can be life-threatening, causing respiratory failure that can lead to death. People with this condition need early and effective treatment. For moderate to severe pneumocystis pneumonia in people with AIDS, the short term use of corticosteroids has decreased the incidence of death.

Possible Complications

When to Contact a Medical Professional

If you have a weakened immune system due to AIDS, cancer, transplantation, or corticosteroid use, call your doctor if you develop a cough, fever, or shortness of breath.

Many infections can lead to similar symptoms. Your health care provider can help rule out opportunistic infections such as pneumocystis.


Preventive therapy is recommended for:

  • Patients with AIDS who have CD4 counts below 200 cells/microliter
  • Bone marrow transplant recipients
  • Organ transplant recipients
  • People who take long-term, high-dose corticosteroids
  • People who have had previous episodes of this infection


Feinberg JE. Pneumocystis pneumonia. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 362.

Review Date: 
Reviewed By: 
Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.