SRG General Parasitology

Introduction to Digenean Flukes

The digeneans are a group of specialised endoparasitic platyhelminthes. A common feature is that all have complex lifecycles, involving one or more intermediate hosts, the first of which is always a mollusc, which is usually aquatic. As adults they found in most vertebrates groups, including fish, amphibians, reptiles, birds, and mammals, acting as definitive hosts, where they may give rise to highly pathogenic infections. They may be located in most of the internal organs of these definitive hosts, including the lungs, bladder and blood stream, although the majority are found in the gastrointestinal tract, or closely associated organs such as the bile duct and liver. They exhibit a flattened leaf-like body, structurally similar to many of the free living turbellarians. The organisation of the digenean body is described in detail in the next section of this page.

There are a number of important diseases in both man and domesticated animals caused by these organisms, those in man being detailed in the human helminth infection page within this site. Links to pages devoted to specific digenean parasites infecting man may be found in the margin of this page. In domesticated animals these parasites are also responsible for many diseases, some of the most important being listed below;

Organism	Disease	Animals Affected
Fasciola hepatica	Fascioliasis	Sheep, cattle, other mammals including man
Dicrocoelium dendriticum	Dicrocoeliasis	Primarily Ruminants
Family Paramphistomatidae	Paramphistomiasis	Ruminants
Schistosoma sp.	Schistomiasis	Many mammals

Adult Fluke