Itchy anus fecal worms refers to a PINWORM INFESTATION:「The pinworm has a worldwide distribution, and is the most common helminth (i.e., parasitic worm) infection in the United States and Western Europe. In the United States, a study by the Center of Disease Control reported an overall incidence rate of 11.4% among people of all ages. Pinworms are particularly common in children, with prevalence rates in this age group having been reported as high as 61% in India, 50% in England, 39% in Thailand, 37% in Sweden, and 29% in Denmark. Finger sucking has been shown to increase both incidence and relapse rates, and nail biting has been similarly associated. Because it spreads from host to host through contamination, pinworms are common among people living in close contact, and tends to occur in all people within a household. …Almost the entire body of a gravid female becomes filled with eggs. The estimations of the number of eggs in a gravid female pinworm range from about 11,000 to 16,000. …They emerge from the anus, and while moving on the skin near the anus, the female pinworms deposit eggs either through (1) contracting and expelling the eggs, (2) dying and then dis-integrating, or (3) bodily rupture due to the host scratching the worm. …Pinworms spread through human-to-human transmission, by ingesting (i.e., swallowing) infectious pinworm eggs and/or by anal insertion. The eggs are hardy and can remain viable (i.e., infectious) in a moist environment for up to three weeks. …After the eggs have been initially deposited near the anus, they are readily transmitted to other surfaces through contamination. The surface of the eggs is sticky when laid, and the eggs are readily transmitted from their initial deposit near the anus to fingernails, hands, night-clothing and bed linen,…food, water, furniture, toys, bathroom fixtures and other objects. …Dust containing eggs can become airborne and widely dispersed when dislodged from surfaces, for instance when shaking out bed clothes and linen. Consequently the eggs can enter the mouth and nose through inhalation, and be swallowed later. …Despite the limited, 13-week lifespan of individual pinworms, autoinfection (i.e., infection from the original host to itself), either through the anus-to-mouth route or through retroinfection, causes the pinworms to inhabit the same host indefinitely. …In humans, [the] primary symptom is itching in the anal area.」
　　[　https://en.wikipedia.org/wiki/Pinworm 2013-09-14　]　

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: parasitic worm; human pinworm (Enterobius vermicularis)
Unihan extended: worms
EDRDG: intestinal worm