|Other names: Pneumocystis jiroveci pneumonia, pneumocystis pneumonia, pneumocystis carinii pneumonia (PCP)|
|Pneumocystosis on chest X-ray|
|Complications||Respiratory failure, perforated ear drum|
|Risk factors||Poor immunity, HIV/AIDS|
|Diagnostic method||Medical imaging, bronchoalveolar lavage, immunofluorescence assay, biopsy|
|Prevention||Trimethoprim/sulfamethoxazole (co-trimoxazole) in high risk groups|
|Prognosis||10 to 50% risk of death|
|Frequency||Uncommon, 97% in lungs|
Pneumocystosis is a fungal infection that usually presents as pneumonia. Symptoms may include cough, difficulty breathing and fever, and can lead to the lungs to stop working. Involvement outside the lungs is rare, but may include lymph nodes, spleen, liver, bone marrow, kidneys, thyroid, and other organs. In the skin, it may present as nodular growths in the ear or underarms.
It is caused by the fungus Pneumocystis jirovecii. It generally only occurs in people with poor immunity such as HIV/AIDS or premature babies. It is an airborne disease. It is often breathed in by healthy people without causing disease, until the person's immune system becomes weakened.
Diagnosis is by identifying the organism from a sample of fluid from affected lungs or tissue biopsy. Prevention in high risk people, and treatment in those affected is usually with trimethoprim/sulfamethoxazole (co-trimoxazole). There is no vaccine. Between 10 to 50% of those infected die as a result.
Pneumocystosis has a worldwide distribution. The precise number of people affected is unknown. More than 97% of cases only involve the lungs. The first cases were described in premature and malnourished babies in Europe following the Second World War.
Signs and symptoms
Pneumocystosis is generally an infection in the lungs. Involvement outside the lungs is rare but, can occur as a disseminated type affecting lymph nodes, bone marrow, liver or spleen. It may also affect skin, eyes, kidneys, thyroid, heart, adrenals and gastrointestinal tract.
When the lungs are affected there is usually a dry cough, difficulty breathing and fever, usually present for longer than four weeks. There may be chest pain, shivering or tiredness. The oxygen saturation is low. The lungs may fail to function.
Pneumocystosis in eyes may appear as a single or multiple (up to 50) yellow-white plaques in the eye's choroid layer or just beneath the retina. Vision is usually not affected and it is typically found by chance.
If occurring in the skin, pneumocystosis most often presents as nodular growths in the ear canals of a person with HIV/AIDS. There may be fluid in the ear. Skin involvement may appear outside the ear, usually palms, soles or underarms; as a rash, or small bumps with a dip. It can occur on the face as brownish bumps and plaques. The bumps may be tender and the skin may break. Infection in the ear may result in a perforated ear drum or destruction of the mastoid bone. The nerves in the head may be affected.
Pneumocystosis occurs predominantly in people with HIV/AIDS. Other risk factors include chronic lung disease, cancer, autoimmune diseases, organ transplant, or taking corticosteroids. It has been reported in premature infants and malnourished children.
Diagnosis of Pneumocystis pneumonia is by identifying the organism from a sample of sputum, fluid from affected lungs or a biopsy. A chest X-ray of affected lungs show widespread shadowing in both lungs, with a "bat-wing" pattern and ground glass appearance. Giemsa or silver stains can be used to identify the organism, as well as direct immunofluorescence of infected cells.
Diagnosis in the eye involves fundoscopy. A biopsy of the retina and choroid layer may be performed. In affected liver, biopsy shows focal areas of necrosis and sinusoidal widening. H&E staining show frothy pink material outside cells. Typical cysts with a solid dark dot can be seen using a Grocott silver stain.
Pneumocystosis has a worldwide distribution. The exact number of people in the world affected is not known. Pneumocystosis affects lungs in around 97% of cases and is often fatal if not treated.
The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the Second World War. It was then known as plasma cellular interstitial pneumonitis of the newborn.
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