Amoebiasis due to free-living amoebae

Amoebiasis due to Free-Living Amoebae Amoebiasis due to free-living amoebae is a rare and often severe infection caused by certain species of amoebae that are not typically parasitic but can cause disease in humans under certain conditions. These amoebae are found in the environment, particularly in soil and water.

Overview

Free-living amoebae are a group of amoebae that can survive in the environment without a host. However, some species can cause infections in humans, particularly when they enter the body through the nasal passages or through skin wounds. The most notable free-living amoebae that cause disease in humans include Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris.

Pathophysiology

The pathophysiology of amoebiasis due to free-living amoebae involves the invasion of the central nervous system or other tissues by the amoebae. For example, Naegleria fowleri causes primary amoebic meningoencephalitis (PAM), a rapidly progressing and often fatal infection of the brain. Acanthamoeba spp. can cause granulomatous amoebic encephalitis (GAE) and amoebic keratitis, while Balamuthia mandrillaris is known to cause GAE as well.

Naegleria fowleri

Naegleria fowleri is commonly found in warm freshwater environments. Infection typically occurs when contaminated water enters the nasal passages, allowing the amoebae to migrate to the brain. The disease progresses rapidly, often leading to death within a week.

Acanthamoeba spp.

Acanthamoeba spp. are found in various environments, including soil, air, and water. They can cause infections in the eyes, skin, and central nervous system. Amoebic keratitis is a serious eye infection that can lead to blindness if untreated.

Balamuthia mandrillaris

Balamuthia mandrillaris is less common but can cause severe infections in the brain and other organs. It is found in soil and dust and can enter the body through skin wounds or inhalation.

Symptoms

The symptoms of amoebiasis due to free-living amoebae vary depending on the species and the site of infection. Common symptoms include:

• Primary Amoebic Meningoencephalitis (PAM): Severe headache, fever, nausea, vomiting, stiff neck, confusion, and seizures.
• Granulomatous Amoebic Encephalitis (GAE): Headache, fever, neurological deficits, and altered mental status.
• Amoebic Keratitis: Eye pain, redness, blurred vision, and sensitivity to light.

Diagnosis

Diagnosis of infections caused by free-living amoebae can be challenging due to their rarity and the rapid progression of symptoms. Laboratory tests, including cerebrospinal fluid analysis, brain imaging, and culture or PCR of the amoebae, are used to confirm the diagnosis.

Treatment

Treatment options are limited and often not very effective, especially for PAM. A combination of antifungal and antimicrobial drugs is typically used, but the prognosis remains poor. Early diagnosis and treatment are critical for improving outcomes.

Prevention

Preventive measures include avoiding exposure to contaminated water, especially in warm freshwater environments, and using proper contact lens hygiene to prevent amoebic keratitis.

See Also

• Naegleria fowleri
• Acanthamoeba spp.
• Balamuthia mandrillaris

External Links

• [CDC - Free-living Amebae](https://www.cdc.gov/parasites/free-living/index.html)

NIH genetic and rare disease info

• NIH info on Amoebiasis due to free-living amoebae

Amoebiasis due to free-living amoebae is a rare disease.