epidemic – n. an occurrence in which a disease spreads very quickly and affects a large number of people

host – n. a living organism on or in which a parasite lives

intermediate host – adj. a host which is normally used by a parasite in the course of its life cycle and in which it may multiply asexually but not sexually

mammals – n. a type of animal that feeds milk to its young and that usually has hair or fur covering most of its skin

pollen – n. the very fine usually yellow dust that is produced by a plant and that is carried to other plants of the same kind usually by wind or insects so that the plants can produce seeds

outbreak – n. a sudden start or increase of fighting or disease

species – n. group of animals or plants that are similar and can produce young animals or plants; a group of related animals or plants that is smaller than a genus