One extreme example is a psychological condition called delusory parasitosis where people believe their bodies are infested with mites or fleas scurrying over and under their skin, making them itch incessantly.
极端例子是种叫做妄想性寄生虫病心理况,人认为他身体被螨虫或跳蚤滋生,在他肤上下窜动,使他不停地发痒。