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Fasciola hepatica. Chad Clark Kelli Rogers. Introduction. Phylum: Platyhelminthes Class : Trematoda Flat Worm Infection results in a Liver Fluke Has important economic impacts around the world Rarely infects humans Causes the disease fascioliasis
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Fasciola hepatica Chad Clark Kelli Rogers
Introduction • Phylum: Platyhelminthes • Class : Trematoda • Flat Worm • Infection results in a Liver Fluke • Has important economic impacts around the world • Rarely infects humans • Causes the disease fascioliasis • Hepatic means “Having to do with the liver” and is derived from the Greek word hepar meaning The Liver
Region and host • Definitive host: - Sheep or cattle • Intermediate host: - Fresh Water Snail (the type of snail will vary depending on region of world you are in) • Accidental host: - Humans • Geographical region: - Anywhere sheep and cattle are raised where fresh water snails are abundant.
Miracidia Egg Cercariae Metacercariae
Adult Fluke • Will set up camp in the liver • Has been described as having a “leaf shape” body - Picture below is a cross section of the adult fluke resembling a “blue pac-man” • Size: - On average they are 30 mm long and 13 mm wide
Clinical Signs • Abdominal Pain (Chronic) • Anemia (Acute) • BiliaryChollic (Chronic) • Hepatic Tenderness (Acute) • Hepatomegaly due to Edema (Acute) • Fever (Can be moderate to severe)(Acute and Chronic) • Fibrosis (Chronic) • Hives (Acute) • Jaundice (Chronic) • Vomiting (Acute)
Pathogenesis • Acute - F. hepatica larvae migrate throughout liver parenchyma - Will penetrate liver capsules and produce acute symptoms for 6-8 weeks until larvae mature and settle in the bile ducts. • Chronic - Metabolic waste of adult flukes causes inflammation of bile ducts eventually leading to fibrosis - Can result in portal cirrohsis or even death • Halzoun - Obtained when an individual eats raw liver - Will settle in the Pharynx causing symptoms for 10 years
Diagnosis • Specific diagnosis depends on finding eggs in the stool can do a fecal egg count (directly observed) using a duodenal aspirate or a biliary aspirate • An enzyme linked immunosorbent assay (ELISA) test is can also be used to determine whether F. hepatica eggs are present can detect up to five weeks earlier then the fecal egg count • Can also use an ultrasound to visualize adult flukes in bile duct • Can use excretory/secretory (E/S) antigens that are specific to F. hepatica
Treatment • Rafoxanide - Acts by uncoupling oxidative phosphorylation in the adult fluke • Triclabendazole - Most effective treatment - Take 1-2 oral doses in a 24 hour period - Many countries have yet to approve of its use (2002) • In severe cases may need to undergo surgery • Overall success rate for treatment of fascioliasis is 80-100%
Control Methods • EDUCATE! - Wash veggies with 6% vinegar or potassium for 5 to 10 minutes to destroy the encysted metacercariae - Physicians and health workers rarely consider possibility of F. hepatica infection when treating patients, giving them an awareness of it would help greatly and reduce future infections. • Keep sheep herds and cattle herds away from areas of water, if area of water present is their drinking grounds then make sure it is free of snails • Molluscicides
Sources • http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/A-F/Fascioliasis/body_Fascioliasis_il5.htm • http://www.stanford.edu/class/humbio103/ParaSites2001/fascioliasis/Fasciola.htm • Foundations of Parasitology • Eighth Edition • Gerald D. Schmidt & Larry S. Roberts & John Janovy, Jr