Experimental pneumonitis induced by Naegleria fowleri in mice.

An environmental Naegleria isolate, from a cooling lake receiving thermal additions from an electric power plant, caused both primary amoebic meningoencephalitis (PAM) and pneumonitis in mice after intranasal inoculation. Amoebae, recovered from brains and lungs of mice inoculated with the environmental isolate, produced both brain and lung infections in repeated mouse passages. Electron microscope examination of infected lungs revealed a moderate inflammatory reaction with slight necrosis. Amoebae re-isolated from mice with PAM and pneumonitis were identified as N. fowleri by the indirect immuno-fluorescent antibody technique using anti-N. fowleri serum. The results suggest that in addition to PAM, N. fowleri may be capable of causing subacute and acute respiratory infections in man.