Types of Parasitic Flatworms

A 2001 study published in "Pedobiologia" reports that when food is in short supply, certain species of flatworm have the ability to undergo a period of degrowth during which they experience a remarkable reduction in body size; oftentimes as much as 97 percent. To this day more than 10,000 species of flatworms have been identified. Included within this diverse group of worms are parasitic flatworms.

Traits

• Segment clearly visible in this microscopic image of a tapeworm

  The majority of parasitic flatworms are endoparasites; they can infect the internal systems of other organisms and feed on their chosen host. Hosts range from companion animals and livestock to humans. There are three classes of parasitic flatworms, each comprising of several subspecies: tapeworms, flukes and monogenea. Tapeworms are segmented, ribbon-like creatures, monogenea are egg-shaped, and flukes resemble narrow leaves.

Tapeworms

• Tapeworms commonly infect the intestinal tracts of vertebrates. The initial host animals for tapeworms are livestock; parasitic infection of humans is usually because of consumption of undercooked meat. Tapeworms are the largest intestinal parasites and can grow up to several yards long. They attach to the host's intestinal wall by their scolex, a structure in the worm's head that contains suckers and hooks. Tapeworm infection is often asymptomatic, especially in its early stages.

Flukes

• Flukes have a three-host life cycle. According to "Parasitology," their initial hosts are mollusks, the intermediary hosts fish and the final hosts mammals. Flukes infect the intestines of humans and latch on to the intestinal wall by using one or two suckers; these are found on their head and abdomen. A fluke infection is dangerous, as worms can travel from the host's intestines to other organs, through the bloodstream and cause serious illness or death.

Monogenea

• Monogenea, until recently were thought to be fluke subspecies but are now recognized as a separate sister-family to flukes. Unlike flukes and tapeworms, monogenea have no suckers and attach to host animals by using hooks. According to a University of Florida 2005 study monogenea are ectoparasites that infect the gills, fins and skin of fish, though rare instances of endoparasitic infection of the bladders and mouths of turtles and amphibians have been reported. Infection is generally not dangerous, though animal deaths caused by monogenea infection do occasionally occur.

Treatment

• Effective treatments do exist for human and animal fluke and tapeworm infection in the form of anti-parasitic medications and there are several ways to both contain and treat marine life monogenea infections, including the introduction of quarantine controls in fish farms and treatment of infected fish with disinfectants or potassium permanganate (see reference 5, management).