haemosporidian: minute protozoans parasitic at some stage of the life cycle in blood cells of vertebrates including many pathogens
sporozoan: parasitic spore-forming protozoan
parasympathetic nervous system: originates in the brain stem and lower part of the spinal cord; opposes physiological effects of the sympathetic nervous system: stimulates digestive secretions; slows the heart; constricts the pupils; dilates blood vessels