Intravenous infection of mice with Naegleria fowleri.

Naegleria fowleri produced fatal meningoencephalitis in mice following intravenous (i.v.) inoculation. Amebae were present in the peripheral circulation for 120 minutes after i.v. inoculation with a dose of 10(7) trophozoites per mouse. Amebae were cultured from and observed in brain (days 1-21), lung (days 1-12), and liver and kidney (days 1-5). Infected mice exhibited weight loss, leukocytosis, reduced lymphocyte/neutrophil ratio, neurologic symptoms, and mortality. Histologically, the disease was characterized by an acute, hemorrhagic, necrotizing meningoencephalitis. Although amebae were detected in tissues other than brain, pathologic involvement of these tissues was minimal.