Final answer:
Scabies happens due to an infestation of mites in the skin, causing intense itching and the development of small red bumps, blisters, and thick, crusty skin.
Step-by-step explanation:
Scabies happens due to an infestation of mites in the skin. Scabies is a highly contagious skin condition caused by the Sarcoptes scabiei mite. The mites burrow into the skin and cause intense itching, especially at night. This infestation can lead to the development of small red bumps, blisters, and thick, crusty skin.