Fatal Infections withBalamuthia mandrillaris(a Free-living Amoeba) in Gorillas and Other Old World Primates

Abstract

Balamuthia mandrillaris is a newly described free-living amoeba capable of causing fatal meningoencephalitis in humans and animals. Because the number of human cases is rapidly increasing, this infection is now considered an important emerging disease by the medical community. A retrospective review of the pathology database for the Zoological Society of San Diego (the San Diego Zoo and San Diego Wild Animal Park) for the period July 1965 through December 1994 revealed five cases of amoebic meningoencephalitis, all in Old World primates. The infected animals were a 3-year, 10-month-old female mandrill (Papio sphinx), from which the original isolation of B. mandrillaris was made, a 5-year-old male white-cheeked gibbon (Hylobates concolor leucogenys), a 1-year-old female western lowland gorilla (Gorilla gorilla gorilla), a 13-year, 5-month-old male western lowland gorilla, and a 6-year-old female Kikuyu colobus monkey (Colobus guereza kikuyuensis). Two different disease patterns were identified: the gibbon, mandrill, and 1-year-old gorilla had an acute to subacute necrotizing amoebic meningoencephalitis with a short clinical course, and the adult gorilla and colobus monkey had a granulomatous amoebic meningoencephalitis with extraneural fibrogranulomatous inflammatory lesions and a long clinical course. Indirect immunofluorescent staining of amoebas in brain sections with a Balamuthia-specific polyclonal antibody was positive in all five animals. Indirect immunofluorescent staining for several species of Acanthamoeba, Naegleria fowleri, and Hartmanella vermiformis was negative. Direct examination of water and soil samples from the gorilla and former mandrill enclosures revealed unidentified amoebas in 11/27 samples, but intraperitoneal inoculations in mice failed to induce disease. Attempts to isolate amoebas from frozen tissues from the adult male gorilla were unsuccessful.

GENOTYPING OF BALAMUTHIA MANDRILLARIS BASED ON NUCLEAR 18S AND MITOCHONDRIAL 16S rRNA GENES

“…Infections also have caused skin lesions, and in a few cases amebae have been found in the kidneys and lungs. 4,10,[13][14][15]17,18 Hemorrhaging of organs in many clinical cases provides evidence that B. mandrillaris had been present in these locations even when amebae were not isolated from the tissue samples. Eventually, patients die of a massive central nervous system infection.…”

“…1,6,10,[15][16][17]23 Currently an immunofluorescence test using species-specific sera is the most reliable means to distinguish between the 2 amebae. In contrast to Acanthamoeba, which has been found readily in soil, water, and sewage, B. mandrillaris has never been isolated from the environment.…”

Amebic Meningoencephalitis Caused by Balamuthia Mandrillaris (Leptomyxid Ameba) in a Horse

“…1,2,5,6,8,[10][11][12][13][14][15][16] The ameba has two stages in its life cycle: a feeding trophic stage and a thick-walled cyst stage. 15 Balamuthia mandrillaris can be successfully cryopreserved and cultured on a variety of mammalian cell cultures.…”

Histopathologic spectrum and immunohistochemical diagnosis of amebic meningoencephalitis

“…1,7,8 Previous histopathologic reports describe single cases or small series of patients infected by one amebic genus. [9][10][11][12][13][14][15][16][17][18][19][20] Side-by-side histopathologic comparison of cases caused by different ameba is not available. To better characterize the central nervous system pathology caused by the three different genera of free-living ameba, we evaluated the histopathologic and immunohistochemical features of patients infected with Acanthamoeba, Balamuthia, and Naegleria.…”