Definition
Fluke
infections are diseases of the digestive tract and other organ systems
caused by several different species of parasitic flatworms (Trematodes)
that have complex life cycles involving hosts other than human beings.
Trematode comes from a Greek word that means having holes and refers to
the external suckers that adult flukes use to draw nourishment from
their hosts. Fluke infections are contracted by eating uncooked fish,
plants, or animals from fluke-infected waters. Symptoms vary according
to the type of fluke infection.
Description
In humans, fluke infections can be classified according to those diseases caused by liver flukes and those caused by lung flukes. Diseases caused by liver flukes include fascioliasis, opisthorchiasis, and clonorchiasis. Cases of liver fluke infection have been reported in Europe and the United States, as well as the Middle East, China, Japan, and Africa. Diseases caused by lung flukes include paragonimiasis. Paragonimiasis is a common infection in the Far East, Southeast Asia, Africa, Central and South America, Indonesia, and the Pacific Islands. It is estimated that between 40 million and 100 million people worldwide suffer from either liver or lung fluke infections.
In
their adult stage, liver and lung flukes are symmetrical in shape,
ranging between 1/4-1 in in length, and look somewhat like long, plump
leaves or blades of grass. They enter through the mouth and can infect
any person at any age.
Causes and symptoms
The
symptoms of fluke infection differ somewhat according to the type of
fluke involved. All forms of liver and lung fluke infection, however,
have the following characteristics:
- most persons who get infected do not develop symptoms (asymptomatic)
- the early symptoms of an acute fluke infection are not unique to these diseases alone (nonspecific symptoms)
- infection does not confer immunity against re-infection by the same species or infection by other species of flukes
- infection is usually associated with eating uncooked fish, plants, or animals that live in fresh water
