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Naegleria australiensis: experimental meningoencephalitis in mice
Abstract:
Naegleria australiensis was recently described as a new species of free-living amoeba pathogenic for mice. Infections of human brain by the free-living amoebae N. fowleri and Acanthamoeba spp. are well known. We here describe the clinicopathological features of experimental infection of the central nervous system of mice by N. australiensis. Weanling mice were inoculated intranasally and intracerebrally. The involvement of the nasal mucosa, olfactory neuroepithelium and lobes, cerebrum and cerebellum was detected in haematoxylin-eosin stained paraffin-embedded sections. Amoebic trophozoites sparsely located throughout the central nervous system were shown better by the immunoperoxidase method. Cysts were not detected. The histopathological changes differ from those produced by N. fowleri, especially in the degree of severity. They may be confused with those caused by Acanthamoeba spp. which usually produced subacute and chronic encephalitis with a prolonged clinical course.
Insights
Naegleria australiensis causes experimental central nervous system infections in mice. Histopathology reveals distinct changes differing from Naegleria fowleri, potentially resembling Acanthamoeba encephalitis.
Area of Science:
- Pathology
- Infectious Diseases
- Neuroscience
Background:
- Naegleria australiensis is a newly identified pathogenic free-living amoeba.
- Human brain infections by Naegleria fowleri and Acanthamoeba spp. are established.
- The pathogenicity of N. australiensis in mammalian central nervous system (CNS) requires further elucidation.
Purpose of the Study:
- To describe the clinicopathological features of experimental CNS infection by Naegleria australiensis in mice.
- To compare the histopathological findings with those of other pathogenic free-living amoebae.
Main Methods:
- Weanling mice were inoculated intranasally and intracerebrally with N. australiensis.
- Histopathological analysis of CNS tissues was performed using hematoxylin-eosin staining.
- Immunoperoxidase staining was employed to detect amoebic trophozoites.
Main Results:
- N. australiensis infected the nasal mucosa, olfactory system, cerebrum, and cerebellum.
- Amoebic trophozoites were observed throughout the CNS, while cysts were absent.
- Histopathological changes differed in severity from N. fowleri infections and showed similarities to Acanthamoeba spp.
Conclusions:
- N. australiensis induces experimental CNS infections in mice with distinct histopathological features.
- The observed pathology may be confused with Acanthamoeba encephalitis, highlighting the need for accurate species identification.