Experimental infections with pathogenic free-living amebae in laboratory primate hosts: I (A) A study on susceptibility to Naegleria fowleri.

Studies were conducted on 27 Old World monkeys to determine their susceptibility to pathogenic strains (HB-1 and C-66) of Naegleria fowleri by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 11 of 18 monkeys inoculated intrathecally succumed to acutely fatal meningoencephalitis, while the other 7 survived with no obvious permanent brain damage. Pathogenicity of N. fowleri appeared to be influenced by the strain virulence, growth phase, and cultural condition of the amebae, as well as age, immune competence, and other as yet unknown host factors.