Pneumocystosis is a fungal infection that most often presents as Pneumocystis pneumonia in people with

HIV/AIDS The HIV, human immunodeficiency virus (HIV) is a retrovirus that attacks the immune system. Without treatment, it can lead to a spectrum of conditions including acquired immunodeficiency syndrome (AIDS). It is a Preventive healthcare, pr ...

or poor immunity. It usually causes

cough A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and Microorganism, microbes. As a protective reflex, coughing can be repetitive with the cough reflex fol ...

, difficulty breathing and fever, and can lead to

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a r ...

. Involvement outside the lungs is rare but, can occur as a disseminated type affecting

lymph nodes A lymph node, or lymph gland, is a kidney-shaped Organ (anatomy), organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphoc ...

, spleen,

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, bone marrow, eyes, kidneys, thyroid, gastrointestinal tract or other organs. If occurring in the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

, it usually presents as nodular growths in the ear canals or underarms. It is caused by '' Pneumocystis jirovecii'', a fungus which is usually breathed in and found in the lungs of 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 a biopsy. Prevention in high risk people, and treatment in those affected is usually with trimethoprim/sulfamethoxazole (co-trimoxazole). The prevalence is unknown. Less than 3% of cases do not involve the lungs. The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

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

, bone marrow,

or spleen. It may also affect

, eyes, kidneys, thyroid,

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

, adrenals and

gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

Lungs

When the lungs are affected there is usually a dry

, 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.

Eyes

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 The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

. Vision is usually not affected and it is typically found by chance.

Skin

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 ulcerate. 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.

Cause

Pneumocystosis is caused by '' Pneumocystis jirovecii'', a fungus which is generally found in the lungs of healthy people, without causing disease until the person's immune system becomes weakened.

Risk factors

Pneumocystosis occurs predominantly in people with HIV/AIDS. Other risk factors include chronic lung disease, cancer, autoimmune diseases, organ transplant, or taking

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invol ...

Diagnosis

X-ray and CT of ground glass opacities and pneumothorax in pneumocystis pneumonia

Diagnosis of ''Pneumocystis'' pneumonia is by identifying the organism from a sample of

sputum Sputum is mucus that is coughed up from the lower airways (the trachea and bronchi). In medicine, sputum samples are usually used for a naked-eye examination, microbiological investigation of respiratory infections, and Cytopathology, cytological ...

, fluid from affected lungs or a biopsy. A

chest X-ray A chest radiograph, chest X-ray (CXR), or chest film is a Projectional radiography, projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common fi ...

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 extracellular frothy pink material. Typical cysts with a solid dark dot can be seen using a Grocott silver stain.

Differential diagnosis

Pneumocystosis may appear similar to

pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain ...

or adult respiratory distress syndrome. Other infections can present similarly such as

tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

Legionella ''Legionella'' is a genus of gram-negative bacteria, gram-negative bacteria that can be seen using a silver stain or grown in a special media that contains cysteine, an amino acid. It is known to cause legionellosis (all illnesses caused by ''Legi ...

, and severe flu.

Prevention

There is no vaccine that prevents pneumocystosis. Trimethoprim/sulfamethoxazole (co-trimoxazole) might be prescribed for people at high risk.

Treatment

Treatment is usually with co-trimoxazole. Other options include pentamidine, dapsone and atovaquone.

Outcomes

It is fatal in 10-20% of people with HIV/AIDS. Pneumocystosis in people without HIV/AIDS is frequently diagnosed late and the death rate is therefore higher; 30-50%.

Epidemiology

The exact number of people in the world affected is not known. Pneumocystosis affects lungs in around 97% of cases and is often fatal without treatment.

History

The first cases of pneumocystosis affecting lungs were described in premature infants in Europe following the

. It was then known as plasma cellular interstitial pneumonitis of the newborn. ''Pneumocystis jirovecii'' (previously called ''Pneumocystis carinii'') is named for Otto Jírovec, who first described it in 1952.

References

{{Authority control Parasitic infestations, stings, and bites of the skin Protozoal diseases Fungal diseases