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

HIV/AIDS Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ...

or poor immunity. It usually causes

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

, 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 rise ...

. 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 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 lymphocytes that inclu ...

spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

, 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 de ...

, 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 A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dise ...

. Prevention in high risk people, and treatment in those affected is usually with

trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...

(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, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposi ...

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,

spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

. It may also affect

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...

kidneys The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

, adrenals and gastrointestinal tract.

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 Shivering (also called shuddering) is a bodily function in response to cold and extreme fear in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Skeletal muscles begin to sh ...

or tiredness. The

oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...

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 (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

. 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.

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, fluid from affected lungs or a

. 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 In pathology, silver staining is the use of silver to selectively alter the appearance of a target in microscopy of histological sections; in temperature gradient gel electrophoresis; and in polyacrylamide gels. In traditional stained glass, silve ...

can be used to identify the organism, as well as

direct immunofluorescence A direct fluorescent antibody (DFA or dFA), also known as "direct immunofluorescence", is an antibody that has been tagged in a direct fluorescent antibody test. Its name derives from the fact that it directly tests the presence of an antigen with ...

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 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 shortness of breath, chest pain particularly upon breathin ...

adult respiratory distress syndrome Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin c ...

. Other infections can present similarly such as

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, i ...

Legionella ''Legionella'' is a genus of pathogenic gram-negative bacteria that includes the species '' L. pneumophila'', causing legionellosis (all illnesses caused by ''Legionella'') including a pneumonia-type illness called Legionnaires' disease and a mil ...

, and severe flu.

Prevention

There is no vaccine that prevents pneumocystosis.

Trimethoprim/sulfamethoxazole Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxa ...

(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

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