Fluke is any one of a large group of parasitic flatworms (see Flatworm). Flukes live in nearly every organ—including the intestine, liver, and lungs—of human beings and other animals. They also live in the blood. Most adult flukes are flat and leaflike, but some are round or long and wormlike. They have one or two suckers that hold them to body tissue in the host (animal in which they live). Most flukes have both male and female reproductive organs.
Flukes have complicated life cycles involving different stages of development and from two to four hosts. The first host is usually a snail, in which the young flukes multiply. Later stages of the fluke enter fish, crabs, insects, or other animals. Some attach to plants.
If a person eats an improperly cooked animal infected by flukes in their early developmental stages, the flukes may infect the person’s body. The early stages of schistosomes (blood flukes) swim in water and burrow through the skin to reach blood vessels. The flukes that infect human beings are common in the Far East, tropical parts of the Western Hemisphere, and Africa.
