Amoebiasis due to free-living amoebae

What it is

From: Orphanet

A rare parasitic disease caused by free-living amoebae belonging to the Acanthamoeba, Naegleria and Balamuthia genera, that are able to survive in an autonomous state in all natural environments and can also parasitize humans. In immunosuppressed individuals Acanthamoeba genus contamination leads to granulomatous amoebic encephalitis (also reported in association with species of the Balamuthia genus) together with other problems including cardiac, cutaneous and pulmonary manifestations, all of which influence the prognosis. In immunocompetent individuals, the Naegleria fowleri species is responsible for primary amoebic meningoencephalitis, the evolution of which is rapidly fatal.

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.

Abnormality of the cerebrospinal fluid · Frequent (79-30%)

An abnormality of the cerebrospinal fluid (CSF).

Atypical behavior · Frequent (79-30%)

Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will.

Brain imaging abnormality · Frequent (79-30%)

An anomaly of metabolism or structure of the brain identified by imaging.

CSF lymphocytic pleiocytosis · Frequent (79-30%)

An increased lymphocyte count in the cerebrospinal fluid.

Fever · Frequent (79-30%)

Body temperature elevated above the normal range.

Headache · Frequent (79-30%)

Cephalgia, or pain sensed in various parts of the head, not confined to the area of distribution of any nerve.

Increased CSF protein concentration · Frequent (79-30%)

Increased concentration of protein in the cerebrospinal fluid.

Infectious encephalitis · Frequent (79-30%)

A disorder of the brain caused by an infectious agent that presents with fever, headache, and an altered level of consciousness. There may also be focal or multifocal neurologic deficits, and focal or generalized seizure activity.

Nausea · Frequent (79-30%)

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

Personality changes · Frequent (79-30%)

An abnormal shift in patterns of thinking, acting, or feeling.

Photophobia · Frequent (79-30%)

Excessive sensitivity to light with the sensation of discomfort or pain in the eyes due to exposure to bright light.

Seizure · Frequent (79-30%)

A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Vomiting · Frequent (79-30%)

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

Abducens palsy · Occasional (29-5%)

Malfunction of the abducens nerve as manifested by impairment of the ability of the affected eye to be moved outward. Patients who develop abducens nerve palsy often present with binocular horizontal diplopia, which is a double vision when looking at objects side by side. There will be a notable weakness of the ipsilateral lateral rectus muscle leading to a deficit in of eye abduction on the affected side. Some patients may present with a constant head turning movement to maintain binocular fusion and to lessen the degree of diplopia.

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal basal ganglia morphology (Occasional (29-5%)); Abnormal brainstem MRI signal intensity (Occasional (29-5%)); Abnormal cerebellum morphology (Occasional (29-5%)); Abnormal cerebral white matter morphology (Occasional (29-5%)); Abnormal cranial nerve physiology (Occasional (29-5%)); Abnormal hypothalamus morphology (Occasional (29-5%)); Abnormality of midbrain morphology (Occasional (29-5%)); Abnormality of the cerebral cortex (Occasional (29-5%)); Abnormality of the medulla oblongata (Occasional (29-5%)); Abnormality of the pons (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: 1-9 / 100 000; Europe; Class only.

Which doctor should you see?

The suggested department for discussing Amoebiasis due to free-living amoebae 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 Amoebiasis due to free-living amoebae. 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.