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Infection of the central nervous system due to Acanthamoeba
1Pathology Department (Neuropathology), Presbyterian-University Hospital, University of Pittsburgh School of Medicine, Pennsylvania 15213.
Abstract:
It is well established that Acanthamoeba castellanii, Acanthamoeba culbertsoni, Acanthamoeba polyphaga, and probably other species of free-living amebas are virulent opportunists capable of producing disease in humans and animals. Human infections involving brain, eyes, skin, and lungs have been reported from all continents. Central nervous system (CNS) infection due to Acanthamoeba species usually occurs in chronically ill, debilitated individuals, some of them receiving immunosuppressive therapy or taking broad-spectrum antibiotics. The disease runs a protracted, insidious clinical course and is known as granulomatous amebic encephalitis. Histopathologically, Acanthamoeba species may produce a multifocal, chronic, or subacute granulomatous encephalitis, with trophozoites and cysts present in CNS lesions. The portal of entry of the amebas into the CNS is probably the respiratory tract or a skin lesion, and the organisms reach the CNS by hematogenous spread. As of 1 January 1989, about 50 cases of granulomatous amebic encephalitis had been reported worldwide, 27 in the United States alone.
Insights
Free-living amebas, including Acanthamoeba species, can cause serious human infections like granulomatous amebic encephalitis. These opportunistic pathogens primarily affect debilitated individuals, often entering through the respiratory tract or skin lesions.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Neuroscience
Background:
- Acanthamoeba species are opportunistic free-living amebas known to cause disease in humans and animals.
- Human infections by Acanthamoeba have been reported globally, affecting the brain, eyes, skin, and lungs.
- Central nervous system (CNS) infections are typically observed in immunocompromised or debilitated individuals.
Purpose of the Study:
- To review the established knowledge on Acanthamoeba infections in humans.
- To describe the clinical presentation and pathology of granulomatous amebic encephalitis (GAE).
- To discuss the potential routes of infection and dissemination of Acanthamoeba to the CNS.
Main Methods:
- Literature review of reported human cases of Acanthamoeba infections.
- Histopathological analysis of CNS lesions in GAE cases.
- Epidemiological data compilation from global reports up to January 1989.
Main Results:
- Acanthamoeba species are virulent opportunists causing diverse human infections.
- Granulomatous amebic encephalitis (GAE) is a protracted CNS disease caused by Acanthamoeba.
- Histopathology reveals multifocal granulomatous encephalitis with amebic trophozoites and cysts in CNS lesions.
Conclusions:
- Acanthamoeba poses a significant threat as an opportunistic pathogen.
- The respiratory tract or skin lesions are likely entry points for CNS Acanthamoeba infections.
- Hematogenous spread is the probable mechanism for amebas reaching the CNS.