These are the principal morphologic differences of the different families of helminths:
|Shape||segmented plane||plane no segmented||cylindrical|
|digestive tube||NOT||Ends in cecum||Ends in anus|
|Sex||Hermaphrodites||Hermaphrodites, except Schistosoma||Dioics|
|hook organ component||oral sucker, botridias and doble Rostellar hooks||Oral sucker||Lips, teeth, filariform extreme and dentary plates|
Parasitic worms are sequential hermaphrodites and reproduce depending on the species of worm, either with the presence of a male and female worm, joining sperm and eggs, producing fertile eggs, such as hookworms, or by breaking off segments that contain both male and female sex organs that are able to produce fertile eggs without the presence of a male or female. (e.g., tapeworms)
All worm offspring are passed on through poorly-cooked meat, especially pork, wild fish, and beef, contaminated water, feces and mosquitoes. However, it is estimated that 40 million Americans are infected with the most common roundworm, the pinworm. Medical experts theorize that widespread intestinal parasite infestation is leading to the rise of colon cancer in the United States.
Worm eggs or larvae or even adults enter the human body through the mouth, anus, nose, or skin, with most species attaching themselves to the intestinal tract. With the presence of digestive enzymes, worm egg shells are dissolved, releasing a brand-new worm; unlike its egg shell, the parasitic worm is protected from the body's powerful digestive enzymes by producing a protective keratin layer.