Final answer:
Scabies is a contagious skin condition caused by the mite Sarcoptes scabiei, characterized by a red itchy rash, which is not to be confused with conditions like eczema.
Step-by-step explanation:
The red, intensely itchy rash caused by the barely visible mite Sarcoptes scabiei is known as scabies. This condition is characterized by a notable rash and severe itching, which is often worse at night. Scabies is highly contagious and spreads via direct skin-to-skin contact. Treatment typically involves the application of topical insecticides such as permethrin cream or oral medications.
It is important not to confuse scabies with other skin conditions such as eczema or allergic reactions like those caused by contact with poison ivy, which also cause itching and rashes but have different causes and treatments.