Naegleria fowleri protozoan Coloured transmission electron micrograph TEM of a section through a Naegleria fowleri protozoan The nucleus red contains a large nucleolus yellow in which ribonucleic acid is synthesised This organism is an opportunistic pathogen of humans causing meningoencephalitis inflammation of the brain and its surrounding membranes when inhaled often by children swimming in fresh water Headaches vomiting sensory disturbance and a fatal coma may occur if the victim is not treated Treatment is with antiprotozoal drugs Magnification x at xcm size