"Anal itching" refers to an uncomfortable sensation or itchiness around the anus, which is the opening at the end of the digestive tract. It can be caused by various things like dry skin, certain health conditions, or poor hygiene. Full definition
That story originates with human pinworms, which do cause serious anal itching. (2ndchance.info)
Although the bright blue substance is most commonly used by orthopedic surgeons and other specialists as a dye or «magic marker» during medical procedures, it's more than just a pretty color; doctors have used it to treat a wide range of ailments, including malaria, urinary tract infections, intractable anal itching, and Alzheimer's disease. (health.com)