immunity – n. the ability of a person or creature to resist an infection by the action of antibodies or white blood cells

amnesia - n. a condition in which a person is unable to remember things because of brain injury, shock, or disease

encounter – v. to come into contact with or face something

outbreak – n. the sudden violent start of something

upsurge – n. a sudden increase or rise — usually + in or of

deleterious - adj. damaging or harmful

specific – adj. clearly defined