Specialty infectious disease | ICD-10 A06.6 | |
Granulomatous amoebic encephalitis (GAE) is a central nervous system disease caused by certain species of free-living amoebae, especially species of Acanthamoeba and Balamuthia mandrillaris.
Contents
The term is most commonly used with Acanthamoeba. In more modern references, the term "balamuthia amoebic encephalitis" (BAE) is commonly used when Balamuthia mandrillaris is the cause.
Pathology
GAE may present in numerous ways. There is no solid definition, as only a handful of patients have presented thus far with GAE. GAE can present with: focal paralysis, seizures, brainstem symptoms, and other neurological problems, some of which may mimic glioma (especially brainstem glioma), or other brain diseases, which may hamper timely diagnosis. These symptoms are caused by inflammatory necrosis of brain tissue brought on by amoebic infiltrates.
Appearance on biopsy
A brain biopsy will reveal the presence of infection by pathogenic amoebas. In GAE, these present as general inflammation and sparse granules. On microscopic examination, infiltrates of amoebic cysts and/or trophozoites will be visible.
Treatment
GAE, in general, must be treated by killing the pathogenic amoebas which cause it.
Acanthamoeba
Even with treatment, the condition is often fatal, and there are very few recorded survivors, almost all of whom suffered permanent neurocognitive deficits. Antifungal drugs including ketoconazole, miconazole, 5-flucytosine and pentamidine have been shown to be effective against GAE-causing organisms in laboratory tests.
Balamuthia
In one case, cloxacillin, ceftriaxone, and amphotericin B were tried.
Two patients survived after being successfully treated with a therapy consisting of flucytosine, pentamidine, fluconazole, sulfadiazine and azithromycin. Thioridazine was also given. Successful treatment in these cases was credited to "awareness of Balamuthia as the causative agent of encephalitis and early initiation of antimicrobial therapy."