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Fasciolopsis buski A. Classification Phylum Plathyhelminthes (flatworms) Class Trematoda (flukes) Family Fasciolidea Fasciolopis buski B. Morphology Fasciolopis buski is considered one of the largest trematodes, with the adult form measuring approximately 60 mm in length. Fasciolopis buski produce about 25,000 eggs per day, each oval and measuring approximately 130 m in length. These eggs cannot be distinguished from the eggs of Fasciola hepatica. Adult form 1 Egg operculum C. Lifecycle and Epidemiology 2 Fasciolopis buski infect both humans and pigs. After ingestion of the metacercariae, excystation occurs in the duodenum and the organism attaches to the wall of the small intestine where it resides. The adult form develops in about 3 months and produces unembryonated eggs, which are egested in the feces. The adults have a life span of about one year. In the water, the eggs become embryonated and release miracidia, which infect the intermediate host, the snail. Within the snail, the miracidia develop into the sporocyst, rediae and cercariae forms. Finally, the cercariae are released from the snail and rest on aquatic plant life. Here, the cercariae undergo encystation to form the metacercariae, which are ingested by the definitive host (pig or human). The pigs are considered the reservoir host. D. Geographic Distribution Fasciolopis buski is found primarily in Asia, specifically in China, Taiwan, Malaysia, and India. It is found especially in areas where humans raise pigs and consume freshwater plants. E. Pathology and Symptoms Many cases are mild or asymptomatic, however, the symptoms of more severe infections include abdominal pain, diarrhea, malabsorption, ulceration, hemorrhaging and intestinal obstruction. Death can result in some individuals. According to the CDC, Prevalence is approximately 1.9 million people infected with Fasciolopis buski in China. Morbidity is much higher in children, with 57% of children in China infected by Fasciolopis buski. 3 F. Diagnosis Diagnosis is done primarily through microscopic identification of eggs in stool samples or vomitus; however, Fasciolopis buski eggs cannot be distinguished from the eggs of Fasciola hepatica. Although the eggs cannot be differentiated, one can determine the type of infection by the organs affected. F. hepatica infects the liver, while F. buski infects the small intestine. Occasionally the adult form can be identified in the samples as well. G. Treatment of the individual Patients are typically treated with praziquantel a drug, which is approved by the FDA, but considered investigational for the treatment of parasites. H. Eradication from the area Methods of eradication include proper sanitation and sewage treatment. It is advised that people avoiding eating uncooked aquatic plants such as water bamboo and water chestnuts. 4 Websites Used Ohio State University College of Biological Sciences http://www.biosci.ohio-state.edu/~parasite/fasciolopsis.html http://link.springer.ny.com/link/service/journals/00436/bibs/1087001/10870 080.htm Atlas of Medical Parasitology Carlo Denegri Foundation http://www.cdfound.to.it/HTML/fas2.htm Centers for Disease Control & Prevention, National Center for Infectious Diseases, Division of Parasitic Diseases, Image Library http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Fasciolopsiasis_il.asp?body= A-F/Fasciolopsiasis/body_Fasciolopsiasis_il_th.htm Centers for Disease Control & Prevention, National Center for Infectious Diseases, Division of Parasitic Diseases, Parasites and Health. http://www.dpd.cdc.gov/dpdx/HTML/Fasciolopsiasis.htm CDC Emerging Infections Diseases Vol. 3 No.3 1997 http://www.cdc.gov/ncidod/eid/vol3no3/hotez.htm DRUGS FOR PARASITIC INFECTIONS The Medical Letter®On Drugs and Therapeutics Published by The Medical Letter, Inc. • 1000 Main Street, New Rochelle, NY 10801 August 2004 http://www.medletter.com/freedocs/parasitic.pdf University of Guelph, Canada http://www.uoguelph.ca/~kkolas/fluke.html Dendinger Spring 2005 5