Adult: the worm looks like a buggy whip, the anterior 3/5 is slender and the posterior 2/5 is thick. It is pinkish gray in color. The female worm is 3-5 cm in length and has a long slender esophageal region. The male is smaller than the female and has a curved tail. The reproductive organs of male and female are all double tubule.
Egg: it is barrel or spindle in shape and 50 x 20µm in size. It is brownish and has a translucent polar plug at either ends. The content of the egg is an undeveloped cell
Female releases 1000 to 7000 unembryonated double-plugged eggs each day.Eggs are deposited onto warm, moist shady soil where they embryonate to the L1 stage.
The emrionate egg is the infective stage and is ingested. L1 hatch from the egg in the small intestine and burrow into the mucosa where they are. Adults migrate to the ileocecal and colon regions. Adult worm is inserted into the wall of the intestine penetrating through the mucosa and into the submucosa where blood is ingested.
Pathogenesis: 1.Light infection: Asymptomatic 3. Heavy infection: Bloody diarrhea, emaciation, prolapse of the anus may occur. Diagnosis: Discover the eggs in feces by saturated brine flotation method or direct fecal smear. Treatment and prevention: Same as those of ascariasis
2.Middle infection: Clinical manifestations are usually abdominal pain, anorexia, diarrhea, constipation .