Granulomatous amoebic encephalitis: ghost response of an immunocompromised host?

Document Type



Biological and Biomedical Sciences


Naegleria fowleri, Acanthamoeba and Balamuthia mandrillaris spp. are known to cause fatal amoebic encephalitis. Here, I attempt to draw attention to these cases, which are reported as ‘granulomatous amoebic encephalitis’ (GAE), and their occurrence in immunocompromised individuals and patients with AIDS. GAE, like any other granulomatous inflammation, can occur only in the presence of ample numbers of CD4+ T-lymphocytes. Extensive reviews of manuscripts published over a period of 50 years on this topic and cytokine studies and/or morphological evidence provided in peer-reviewed published studies were evaluated in detail by independent resources to analyse the granulomatous inflammatory evidence provided to justify the title of GAE in this group of patients. The evidence given in support of GAE did not appear to be convincing enough in the majority of published studies, and in particular its occurrence in patients with AIDS and other immunocompromised states was not justified. The distinction between the early development of type IV hypersensitivity reactions and granuloma/granulomatous inflammation was found to be vague and inconclusive. It is therefore recommended that this terminology is used only when all the diagnostic criteria have been met, and use of a term such as ‘granulomatoid’ is suggested in cases where there remains an ambiguity in the morphological appearance of the lesions, especially in AIDS and related diseases.

Publication (Name of Journal)

Journal of Medical Microbiology