Section I. ROUNDWORMS (NEMATODES) DISEASES
a. The word helminth means worm. Helminthic diseases are diseases caused
by parasitic worms. The most common human intestinal helminths are included in two
large groups: nematodes or roundworms and platyhelminthes or flatworms. Two
classes of platyhelminthes are important to human beings: trematodes (flukes) and
cestodes (also called tapeworms). Disease-producing roundworms include hookworms
and pinworms which live in the intestines; trichinal worms which infect the muscles; and
filarial worms which invade the fluids beneath the skin. Disease-producing flatworms
include tapeworms which live in the intestines and flukes which can invade the blood,
intestines, liver, or lungs.
b. During your tour of duty in the Army, you are going to travel worldwide. You
may encounter helminthic diseases common in the United States and some rarely seen
in the US. In this lesson, you will learn to identify helminthic diseases of military
importance. Your ability to recognize these diseases is of great importance to you and
the troops you support.
Roundworms (nematodes) are a group of slender, round worms, the main
species of which are parasitic. This group includes about 500,000 species, 50 of which
are parasites of man. The worms are nonsegmented with flattened, cylindric bodies
which taper toward both ends. The mouth is frequently surrounded by thick lips or
papillae. The sexes are distinctive with the male being shorter and more slender than
the female. They range from so small as to be seen only with a microscope to over 3
feet. They live in water and air as well as plants and animals. The two basic groups of
nematodes are intestinal nematodes and tissue nematodes.
Figure 3-1. Nematode.