Microsporidiosis

What it is

From: Orphanet

A rare parasitic disease characterized by chronic diarrhea leading to severe weight loss caused by microsporidia contamination (most commonly by Encephalitozoon or Enterocytozoon). Contamination can occur through ingesting spores present in water or food or via direct human-to-human contact. Immunodeficient patients (such as individuals with HIV, and patients who have undergone a bone marrow or organ transplant) may be severely affected. These protozoan parasites mainly develop in intestinal cells, but can also be found in adipocytes, epithelial cells and blood cells.

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.

Abdominal pain · Frequent (79-30%)

An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) and perceived to originate in the abdomen.

Chronic diarrhea · Frequent (79-30%)

The presence of chronic diarrhea, which is usually taken to mean diarrhea that has persisted for over 4 weeks.

Decreased proportion of CD4-positive T cells · Frequent (79-30%)

Abnormal decrease of helper CD3+CD4+ T cells, measured as percentage of total CD3+ T cells in the blood, compared to a reference range for a given sex and age-group. These are usually measured within the TCR alpha/beta positive population.

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.

Intermittent diarrhea · Frequent (79-30%)

Repeated episodes of diarrhea separated by periods without diarrhea.

Weight loss · Frequent (79-30%)

Reduction of total body weight.

Anorexia · Occasional (29-5%)

Lack of desire to eat (loss of appetite).

Bronchitis · Occasional (29-5%)

Inflammation of the large airways in the lung including any part of the bronchi from the primary bronchi to the tertiary bronchi.

Fever · Occasional (29-5%)

Body temperature elevated above the normal range.

Nausea · Occasional (29-5%)

A sensation of unease in the stomach together with an urge to vomit.

Rhinitis · Occasional (29-5%)

Inflammation of the nasal mucosa with nasal congestion.

Sinusitis · Occasional (29-5%)

Inflammation of the paranasal sinuses owing to a viral, bacterial, or fungal infection, allergy, or an autoimmune reaction.

Vomiting · Occasional (29-5%)

Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions.

Abnormality of the urinary system physiology · Occasional (29-5%)

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal trachea morphology (Very rare (<4-1%)); Abnormal vocal cord morphology (Very rare (<4-1%)); Abnormality of bone marrow cell morphology (Very rare (<4-1%)); Abnormality of the endometrium (Very rare (<4-1%)); Abnormality of the fallopian tube (Very rare (<4-1%)); Abnormality of the parathyroid gland (Very rare (<4-1%)); Abnormality of the spleen (Very rare (<4-1%)); Biliary tract abnormality (Very rare (<4-1%)); Brain abscess (Very rare (<4-1%)); Bronchiolitis (Very rare (<4-1%)). 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 Microsporidiosis 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

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Microsporidiosis. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

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.