Comparative neuropathology of granulomatous amoebic encephalitis caused by Acanthamoeba spp. across species

Acanthamoeba species are free-living amoebae that cause granulomatous amoebic
encephalitis, a rare but frequently fatal infection of the central nervous system that
predominantly affects immunocompromised individuals. The disease is characterised by a
subacute to chronic course, diagnostic difficulty, and marked heterogeneity in clinical
presentation. Here, we describe a comparative analysis of the neuropathology of
Acanthamoeba encephalitis across humans and animals, highlighting conserved features of
haematogenous dissemination, perivascular tropism, granulomatous inflammation, and chronic
tissue destruction. Across species, both trophozoites and cysts persist within neural tissue,
reflecting prolonged host–pathogen interaction rather than acute cytolysis. Despite variability
in lesion distribution and disease kinetics, the fundamental pathological signature of
Acanthamoeba encephalitis is remarkably conserved. These observations validate the use of
animal models for mechanistic investigation and therapeutic development and clarify key
processes underlying this devastating opportunistic infection.