Last updated: 8/21/2024
Years published: 2018, 2024
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, Stephanie Phan, NORD Editorial Intern from the Keck Graduate Institute, and Charles F. Thomas, Jr., MD, Associate Professor of Medicine, Division of Pulmonary & Critical Care Medicine, Mayo Clinic, for assistance in the preparation of this report.
Pneumocystis pneumonia is a type of infection of the lungs (pneumonia) in people with a weak immune system. It is caused by a yeast-like fungus called Pneumocystis jirovecii (PJP). People with a healthy immune system donโt usually get infected with PCP. It becomes a problem only for people with a weak immune system that allows the fungus to cause infection. The immune system can be weakened by cancer, HIV infection or AIDS, high dose corticosteroids, or from medicine taken after having a bone marrow or organ transplant
PJP is the most common opportunistic infection in people with HIV, and it may cause mild symptoms. In those who are not HIV-positive, PJP usually leads to more severe symptoms, such as severe respiratory failure, fever, and a dry cough.
Symptoms may include respiratory problems as nearly all people affected with PJP have low levels of oxygen in their blood (hypoxemia), which can occur at rest or during physical activity. This condition makes breathing difficult. Other symptoms may include fever and dry cough. However, because the immune system is compromised, these symptoms can be more severe.
Treatment includes antibiotics such as trimethoprim and sulfamethoxazole (TMP/SMX).
Pneumocystis pneumonia is characterized by a gradual onset with shortness of breath and/or difficulty breathing.
Other symptoms may include:
While these symptoms primarily affect the lungs, in rare cases, the fungus that causes PJP can spread to other parts of the body, such as the liver, kidneys and spleen, as the disease progresses.
Pneumocystis pneumonia is caused by the yeast-like fungus Pneumocystis jirovecii that most commonly presents as an opportunistic infection in HIV infected patients, but may present in a variety of people with weak immune systems. Most individuals infected are unaware of their HIV infection at the time of presentation and thus are not receiving PJP prophylaxis and are more prone to acquire PJP.
While there isnโt a national tracking system for pneumocystis pneumonia (PJP) in the United States, itโs estimated that there were about 10,590 hospitalizations due to PJP in the U.S. in 2017.
In the 1980s, PJP was one of the first signs that alerted doctors to the emerging HIV/AIDS epidemic in the United States. It became one of the key illnesses that defined AIDS, with an estimated three out of four people living with HIV/AIDS developing PJP at some point.
Fortunately, the number of people with HIV who get PJP has dropped much since then. This is largely due to the availability of antiretroviral therapy (ART) and the use of the antibiotic combination TMP/SMX (trimethoprim/sulfamethoxazole) for prevention and treatment. However, in some developing countries where access to these treatments is limited, PJP remains a common infection among people living with HIV.
PJP is also more common in other groups of people who are also at risk, especially those with weakened immune systems. These groups include people taking high doses of glucocorticoids or other immunosuppressive drugs, usually used after organ transplants or to treat cancer, and people with certain inflammatory conditions like granulomatosis with polyangiitis (Wegenerโs), polymyositis, or dermatomyositis.
The diagnosis of Pneumocystis pneumonia requires multiple tests such as a chest X-ray and a sample of sputum from the personโs lungs, collected by a procedure called bronchoalveolar lavage to differentiate PJP between from other causes of pneumonia.
Samples are analyzed in clinical laboratories. One method that can be used is polymerase chain reaction (PCR) which detects PJP DNA. A blood test to detect ฮฒ-D-glucan (a part of the cell wall of many different types of fungi) can also help diagnose PJP.
Sometimes, a small sample of lung tissue (biopsy) is used to diagnose PCP or take a blood sample.
Treatment
PJP infection can be serious, but many people can be treated at home with antibiotics such as trimethoprim and sulfamethoxazole (TMP/SMX), a medication also known as co-trimoxazole and by several different brand names (Bactrim, Septra and Cotrim). This medicine is given by mouth or through a vein for 3 weeks. TMP/SMX can cause side effects such as rash and fever.
In people who are allergic to TMP-SMX, which is the most effective treatment for PJP, the doctor may suggest a process called desensitization. This is where the treatment starts with very small doses of the medication, and it is gradually increased to help the body tolerate it.
However, if someone had a severe allergic reaction to TMP-SMX in the past, itโs important that TMP-SMX is avoided, and desensitization should not be done. There are also different alternative therapies for people who cannot take TMP/SMX such as atovaquone, dapsone, primaquine w/ clindamycin and pentamidine. Oxygen therapy may be needed to help get more oxygen into the lungs and bloodstream.
There is no vaccine to prevent PJP infections. Medicine to prevent it is recommended for people living with a low immune system such as people infected with HIV, stem cell transplant patients and some solid organ transplant patients. Healthcare providers might also prescribe medicine to prevent the disease in people who are taking long-term, high-dose corticosteroids.
The medicine most used to prevent PJP infection is TMP/SMX. Other medicines are available for people who cannot take TMP/SMX.
Note that unlike other fungal diseases PJP is treated with an antibiotic. Antifungal medications do not work to treat it.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government website.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
JOURNAL ARTICLES
Robert-Gangneux F, Belaz S, Revest M, et al. Diagnosis of Pneumocystis jirovecii pneumonia in Immunocompromised patients by real-time PCR: a 4-year prospective study. Warnock DW, ed. Journal of Clinical Microbiology 2014;52(9):3370-3376. doi:10.1128/JCM.01480-14.
Huang L, Cattamanchi A, Davis JL, et al. HIV-associated Pneumocystis pneumonia. Proceedings of the American Thoracic Society 2011;8(3):294-300. doi:10.1513/pats.201009-062WR.
Harris JR, Balajee SA, Park BJ. Pneumocystis jirovecii pneumonia: current knowledge and outstanding public health issues. Curr Fung Infect Rep. 2010;4:229-37.
Kovacs JA, Hiemenz JW, Macher AM, et al. Pneumocystis carinii pneumonia: a comparison between patients with the acquired immunodeficiency syndrome and patients with other immunodeficiencies. Annals of Internal Medicine 1984;100:663-71.
INTERNET
Thomas CF and Limper AH. Epidemiology, clinical manifestations, and diagnosis of Pneumocystis pneumonia in HIV-uninfected patients. UpToDate. Nov 16, 2023. https://www.uptodate.com/contents/epidemiology-clinical-manifestations-and-diagnosis-of-pneumocystis-pneumonia-in-patients-without-hiv Accessed Aug 21, 2024.
Pneumocystis Pneumonia Basics. Centers for Disease Control and Prevention. April 24, 2024. https://www.cdc.gov/pneumocystis-pneumonia/about/index.html Accessed Aug 21, 2024.
Pneumocystis jiroveci pneumonia. MedlinePlus Medical Encyclopedia. MedlinePlus. 12/31/2023. https://medlineplus.gov/ency/article/000671.htm Accessed Aug 21, 2024.
Mandanas RA and Anariba DEI. Fungal Pneumonia Overview of Fungal Pneumonia. Medscape. Updated: Jun 26, 2024. https://emedicine.medscape.com/article/300341-overview Accessed Aug 21, 2024.
Thomas CF and Limper AH. Treatment and prevention of Pneumocystis pneumonia in patients without HIV. UpToDate. Jul 17, 2024. https://www.uptodate.com/contents/treatment-and-prevention-of-pneumocystis-pneumonia-in-patients-without-hiv Accessed Aug 21, 2024.
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