PARASITES & POLLUTION...........................................
The word “parasites” is used in two senses. Everything liv-
ing on you or in you, not just to perch, but to take its food from
you is a parasite. No matter what its size, it can be called a
parasite.
But in some way the big worms need to be distinguished from
the medium-sized amoebae, the even smaller bacteria and the
smallest of all—viruses. So often the term parasite is reserved
for the bigger things, from amoebae on up. In this book, the word
parasite will be used in both ways as usual. You can easily guess
what is meant.
Parasitic worms are divided into roundworms and flat-
worms. Roundworms are round like earthworms even though they
may be as thin as hairs (threadworms, filaria) or micro-
scopically small (like Trichinella). Flatworms are more like
leeches. They have a way to attach themselves sometimes with
the head (scolex) like tapeworms, sometimes with a special
sucker like flukes.
WormsFlatworms RoundwormsTapeworms Flukes Threadworms Pinworms HookwormsWorm parasites go through stages of development that can
look very, very different from the adult.