Fasciolopsiasis

Kingdom: Animalia

Phylum: Platyhelminthes

Class: Trematoda

Family: Fasciolidae

Genus: Fasciolopsis

Species:Fasciolopsis buski

Fasciolopsis buski is commonly called the giant intestinal fluke. It is a common parasite of humans and pigs and is most prevalent in Asia, mainly central and southeast Asia. It is in the class Trematoda, family Fasciolidae. The reason for its common name is due to the fact that it is one of the largest flukes to infect humans. The worm inhabits the upper region of the small intestine and, when abundant, can also be found in the lower areas of the intestine and the stomach. Fasciolopsis buski is the cause of Fasciolopsiasis.
Morphology
    F. buski is a large leaf-shaped worm that is characterized by a blunt anterior end, undulating, unbranched ceca (sac-like cavity with a single opening), tandem, dendritic testes, branched ovaries, and ventral suckers to attach itself to the host. The acetabulum is larger than the oral sucker. It has extensive vitelline follicles. It can be distinguished from other fasciolids by a lack of cephalic cone or "shoulders" and the unbranched ceca. The size of an adult worm can reach up to 3 inches in length and 1 inch in width.

Life Cycle

 Adults produce over 25,000 eggs every day which take up to seven weeks to mature and hatch at 27 degree Celsius to 32 degree Celsius. Immature, unembryonated eggs are discharged into the intestine and stool. In two weeks, eggs become embryonated in water, and after about seven weeks, eggs release tiny parasitic organisms called miracidia, which invade a suitable snail intermediate host. Several species of genera Segmentina and Hippeutis serve as intermediate hosts. In the snail the parasites undergo several developmental stages (sporocysts, rediae, and cercariae). The cercariae are released from the snail and encyst as metacercariae on aquatic plants such as water chestnut, water caltrop, lotus, bamboo, and other edible plants. The mammalian host, or the final host, becomes infected by ingesting metacercariae on the aquatic plants. After ingestion, the metacercariae excyst in the duodenum in about three months and attach to the intestinal wall. There they develop into adult flukes (20 to 75 mm by 8 to 20 mm) in approximately 3 months, attached to the intestinal wall of the mammalian hosts (humans and pigs). The adults have a life span of about one year.
Symptoms
   Most infections are light and asymptomatic. In heavy infections, symptoms can include: Abdominal pain, chronic diarrhea, anemia, ascites, toxemia, allergic responses, sensitization caused by the absorption of the worms allergenic metabolites (may eventually cause death of patient), and intestinal obstruction.
The attachment of worm in the small intestine is often accompanied by inflammation and bleeding of infected area, jaundice, diarrhea, gastric discomfort and edema. Such symptoms often mimic that of a person suffering from malabsorption syndrome ,similar to that seen patients with giardiasis.
Laboratory Diagnosis
    Microscopic identification of eggs, or more rarely of the adult flukes, in the stool or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica.
Treatment
Praziquantel is the preferable drug for treatment. Treatment is effective in early or light infections. Heavy infections are more difficult to treat.
Studies of the effectiveness of various drugs for treatment of children with F. buski have shown Tetrachloroethylene as capable of reducing faecal egg counts by up to 99%. Other anthelminths that can be used include thiabendazole, mebendazole, levamisole and pyrantel pamoate.