Pneumocystosis

What it is

From: Orphanet

Human pneumocystosis is caused by an infectious agent, which (after recent nomenclature and taxonomy revisions) is now classed as the fungus Pneumocystis jiroveci. The prevalence is unknown. Pneumocystis jiroveci is an opportunistic infectious agent, developing in immunosuppressed patients. It is an air-borne infection, localised to the lungs. However, extrapulmonary involvement is seen in AIDS patients. The disease manifests progressively with coughing, respiratory problems (dyspnea) and fever, followed by acute respiratory insufficiency and death within a few weeks in untreated cases. The most reliable diagnostic method is bronchoalveolar lavage. The treatment of choice is cotrimoxazole.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Acute infectious pneumonia · Very frequent (99-80%)

Acute inflammation of the lung due to an infection.

Dyspnea · Very frequent (99-80%)

Difficult or labored breathing. Dyspnea is a subjective feeling only the patient can rate, e.g., on a Borg scale.

Fever · Very frequent (99-80%)

Body temperature elevated above the normal range.

Hypoxemia · Very frequent (99-80%)

An abnormally low level of blood oxygen.

Pneumocystis jirovecii pneumonia · Very frequent (99-80%)

An opportunistic disease caused by invasion of unicellular fungus Pneumocystis jirovecii. Transmission of P. jirovecii cysts takes place through the airborne route, and usually, its presence in lungs is asymptomatic. However, people with impaired immunity, especially those with CD4+ T cell count below 200/microliter, are still at risk of the development of Pneumocystis pneumonia due to P. jirovecii invasion. Symptoms induced by this disease are not specific: progressive dyspnea, non-productive cough, low-grade fever, arterial partial pressure of oxygen below 65 mmHg, and chest radiographs demonstrating bilateral, interstitial shadowing.

Abnormal neutrophil count · Frequent (79-30%)

A deviation from the normal range of neutrophil cell counts in the circulation.

Combined cystic and ground-glass pattern on pulmonary HRCT · Frequent (79-30%)

Co-occurrence of the cystic pattern and the ground-glass pattern on pulmonary high-resolution computed tomography,

Exertional dyspnea · Frequent (79-30%)

Perceived difficulty to breathe that occurs with exercise or exertion and improves with rest.

Immunodeficiency · Frequent (79-30%)

Failure of the immune system to protect the body adequately from infection, due to the absence or insufficiency of some component process or substance.

Increased circulating immunoglobulin concentration · Frequent (79-30%)

An increased level of gamma globulin (immunoglobulin) in the blood.

Nonproductive cough · Frequent (79-30%)

A cough that does not produce phlegm or mucus.

Pleural effusion · Frequent (79-30%)

The presence of an excessive amount of fluid in the pleural cavity.

Respiratory failure · Frequent (79-30%)

A severe form of respiratory insufficiency characterized by inadequate gas exchange such that the levels of oxygen or carbon dioxide cannot be maintained within normal limits.

Respiratory failure requiring assisted ventilation · Frequent (79-30%)

A state of respiratory distress that requires a life saving intervention in the form of gaining airway access and instituting positive pressure ventilation.

Other findings in the same source

From: Orphanet

Additional reported features include Weight loss (Frequent (79-30%)); Interstitial pneumonitis (Frequent (79-30%)); Respiratory insufficiency (Frequent (79-30%)); Bloodstream infectious agent (Occasional (29-5%)); Chronic oral candidiasis (Occasional (29-5%)); Increased circulating lactate dehydrogenase concentration (Occasional (29-5%)); Multiple pulmonary cysts (Occasional (29-5%)); Neoplasm (Occasional (29-5%)); Parenchymal consolidation (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

All ages

Inheritance in the source

From: Orphanet

Not applicable

Frequency and the population described

From: Orphanet

Point prevalence: Unknown; Worldwide; Class only.

Which doctor should you see?

The suggested department for discussing Pneumocystosis is Infectious Diseases, with a general physician / infectious disease specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which exposure or organism is suspected, and what evidence would confirm it?
• Are precautions, vaccination or advice for close contacts relevant to this infection?
• What should happen if symptoms worsen or do not improve as expected?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.