Experimental Infections with Pathogenic Free-Living Amebae in Laboratory Primate Hosts: I. (B) a Study on Susceptibility to Acanthamoeba culbertsoni

Abstract

Susceptibility to A. culbertsoni was studied in 15 Old World monkeys by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 4 of 7 monkeys inoculated intrathecally succumbed to acutely fatal meningoencephalitis. Virulence of the ameba varied with cultural age of the inoculum. Size of inoculum, passages through animal tissues, and host-immune competence were other factors of consideration in pathogenicity of the ameba.

Overview of known non-human primate pathogens with potential to affect colonies used for toxicity testing

“…and B. mandrillaris can cause granulomatous amoebic encephalitis in immunocompromised hosts (Schuster and Visvesvara, 2004). Acute fatal meningoencephalitis has been demonstrated by experimental infection with A. culbertsoni or N. fowleri, and spontaneous acanthamoeba infection in an SIV-infected rhesus macaque was associated with necrotizing meningoencephalitis and pneumonitis (Wong et al, 1975a(Wong et al, , 1975bWestmoreland et al, 2004). B. mandrillarisassociated meningoencephalitis has been observed in Old World primates, but infection in macaques has not been reported (Rideout et al, 1997).…”

Immunity to pathogenic free-living amoebae: role of cell-mediated immunity

“…Culbertson et al (3) observed granuloma formation, which is an indicator of a CMI response, in guinea pigs infected subcutaneously with N. fowleri, and the common finding of a granulomatous response and distinctive pathological lesions in Acanthamoeba infections has been commented upon (2,11). Further indirect support of CMI and of the hypothesis that constitutive phagocytes play a decisive role in resistance to infection by PFLA is demonstrated by the increased susceptibility to infection by PFLA exhibited by corticosteroid-treated animals (2,7,10,14,15).…”

“…Experimentally, animal challenge studies have demonstrated that primates are relatively resistant to either intranasal or intravenous challenge with N. fowleri or A. culbertsoni (2,14,15). Intrathecal or intracerebral challenge, however, routinely results in infection by these amoebae.…”

Modeling the Dose Response Relationship of Waterborne Acanthamoeba

“…9 to additional strains and species, because the A1 and HN‐3 strain could be represented by a single dose response relationship. However, it should be noted that another study exposed monkeys intranasally to the A1 strain of A. culbertsoni with doses greater than 10 6 amebae and saw 100% survival (Wong, Karr, & Balamuth, 1975). The pooled model in Table III and Fig.…”