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.

个极端的例子是做妄想性寄生病的心理况，人们认为他们的身体被跳蚤滋生，在他们的皮肤上下窜动，使他们不停地发痒。