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Naegleria and Acanthamoeba infections: review
P Ma1, G S Visvesvara, A J Martinez
1St. Vincent's Hospital and Medical Center, New York.
Abstract:
Infections caused by small, free-living amebas are still unfamiliar to many clinicians, pathologists, and laboratorians. As of 31 July 1989, more than 140 cases of primary amebic meningoencephalitis caused by Naegleria fowleri and more than 40 cases of granulomatous amebic encephalitis caused by Acanthamoeba species (including two cases in patients with AIDS) and possibly by other free-living amebas had occurred worldwide. The recent increase in acanthamoeba keratitis (more than 200 cases), especially in contact lens wearers, has generated new interest in this group of amebas. Effective treatment is still lacking. Risk factors, clinical manifestations, and laboratory parameters helpful in the recognition of infections of the central nervous system (i.e., granulomatous amebic encephalitis and primary amebic meningoencephalitis) and acanthamoeba keratitis are reviewed.
Insights
Free-living amebas like Naegleria fowleri and Acanthamoeba cause rare but serious infections, including primary amebic meningoencephalitis and granulomatous amebic encephalitis. Current treatments are limited, highlighting the need for better diagnostics and therapies.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Clinical Neurology
Background:
- Infections by free-living amebas are infrequently recognized by healthcare professionals.
- Over 140 cases of primary amebic meningoencephalitis (PAM) due to Naegleria fowleri and over 40 cases of granulomatous amebic encephalitis (GAE) due to Acanthamoeba have been reported globally.
- A rise in Acanthamoeba keratitis cases, particularly among contact lens wearers, has increased interest in these pathogens.
Purpose of the Study:
- To review risk factors, clinical presentations, and diagnostic laboratory findings for amebic infections of the central nervous system (CNS) and the eye.
- To provide clinicians, pathologists, and laboratorians with information to aid in the recognition of these uncommon infections.
Main Methods:
- Literature review of documented cases and clinical studies.
- Analysis of epidemiological data up to July 1989.
- Synthesis of clinical manifestations and laboratory parameters associated with PAM, GAE, and Acanthamoeba keratitis.
Main Results:
- Naegleria fowleri causes PAM, a severe CNS infection.
- Acanthamoeba species cause GAE, including in immunocompromised individuals (e.g., AIDS patients).
- Acanthamoeba keratitis is a significant cause of corneal disease, especially in contact lens users.
Conclusions:
- Effective treatments for amebic meningoencephalitis and keratitis remain a challenge.
- Early recognition of clinical signs and laboratory indicators is crucial for patient management.
- Further research is needed to improve therapeutic strategies against free-living amebic infections.