the.com/infestation

means a state in which pests, parasites, or unwanted organisms have spread through a place or body in troublesome numbers

from From Latin infestare, "to attack, trouble, or molest," built on infestus, "hostile" — a word that carried real menace, suggesting an enemy laying siege. It came into English through French in the late Middle Ages, first describing harassment by hostile forces before it narrowed to the smaller invaders — the lice, the rats, the roaches — that besiege a home all the same.