Fasciola hepatica Sarah Richards Max Karpyak

Scientific Classification Kingdom: Animalia Phylum: Platyhelminthes Class: Trematoda Subclass: Digenea Prder Echinostomida Family: Fasciolidea Genus: Fasciola Species:hepitica

General Information - Commonly known as liver fluke - A parasitic flatworm

Geographical Distribution - Found in Rural areas of temperate and tropical regions - Especially located in regions with cattle and sheep herding - Found on every continent with nearly 180 million people at risk and an estimated 2.4 million people already infected worldwide.

Transmission - Occurs through the ingestion of raw, fresh water vegetation - Plants become exposed to the metacercariae when the body of water that the vegetation is growing in becomes contaminated by eggs in the fecal mater of the infested host - A form of infection known as halzoun (in the Middle East) is contracted by eating the raw liver of an infected animal

Morphology - Adult has a flat leaflike body - About mm long by 8-15 mm wide - Has an anterior elongation where oral and ventral suckers are located - Intestines are very branched

Hosts - Cattle - Sheep - Sometimes humans

Life Cycle

Life Cycle (Cont’d) - The adult F. hepatica lives in bile ducts of the host’s liver - Begin to produce eggs 2-4 months after initial infection -Eggs pass down the bile duct through gastrointestinal tract and are released in the hosts feces -Require water of temperature above 10 C to hatch -The egg hatches and releases miracidiae within two weeks -These newly hatched miracidiae must find a Lymanae snail host within 24 of hatching or they will die

Life Cycle (Cont’d) - Inside the Lymanaea miracidium loses its cilia and develops into a sporocyst - Each sporocyst develops into a ridia which then burst the sporocyst and migrate to the hepato- pancreas of the snail - Ridia then develop into cercariae - Cercariae attach to plant matter and encyst, forming metacercariae which is the infective form of the fluke - Mammalian host consumes the vegetation with the metacercariae which then excyst in the small intestine

Life Cycle (Cont’d) - Metacercariae burrow through the intestinal wall, move through the peritoneal cavity and enter the liver parenchyma - Immature flukes migrate through the liver patanchyma for 6-8 weeks giving rise to acute symptoms - Once mature they settle in the bile ducts and begin to produce their own eggs after about a month.

Four Symptomatic Patterns -Acute Phase -Cronic Phase -Halzoun -Ectopic Infection

Acute Phase - Rarely seen in humans - Fever, tender hepatomegaly, and abdominal pain are frequent symptoms. - Vomiting, diarrhea, and anemia may also be present

Cronic Phase - More common in human population - Symptoms include: bilary cholic, abdominal pain, tender hepatomegaly, and jaundice - In children: severe anemia is common - Inflammation of the bile ducts eventually leads to fibrosis and a condition called “pipestem liver” - Severe infections can lead to death

Halzoun & Ectopic Infection - Occurs when an individual consumes infected raw liver - The adult worms can cause considerable pain, edema, and bleeding that can interfere with respiration - Adults can live in biliary ducts and cause symptoms for up to 10 years. - In frequent, but can occur in peritoneal cavity, intestinal wall, lungs, subcutaneous tissue, and very rarely in other locations.

Diagnostic Tests - Most widely used form of diagnosis is the directly observed presence of F. hepatica eggs either in a stool sample, duodenal aspirate or biliary aspirate - Flukes do not begin to produce eggs until about 4 months after infection, so you cannot test the stool - Prior to 4 months: serological tests can be used -FAST-ELISA (most popular) - Ultrasound can be used to visualize adult flukes in the bile ducts - CT scan can reveal burrow tracts made by the worms

Treatment - Many countries use a 5-10 day course of oral bithionol at 30mg/kg body weight - Triclabendazole is a preferred antihelmintic agent, but is unavailable in most countries. -The resistance is rising to this drug - Along with pharmaceutical therapy, surgery may be necessary in very extreme cases to clear the biliary tract

Control Methods - Education - Molluscicides: application of malluscicides to decrease the population of Lymnaea snails - Chemotherapy

Review Questions - 1. What is the average size of an adult F. hepatica? a.20 mm x 5mm b.30 mm x 13 mm c.10 mm x 5 mm 2. What continent can F. Hepatica be found? a.Africa b.Asia c.America d.All of the above

Review (Cont’d) - 3. What is the most effective way to treat fascioliasis? a. bithionol b. flagyl c. triclabendazole

References - “Fascioliasis” Retrieved: 2/19/ oliasis/Fasciola.htm oliasis/Fasciola.htm oliasis/Fasciola.htm - “Fasciola hepatica.” Wikipedia, free encyclopedia. Retrieved: 2/19/ “Fasciola hepatica.” Retrieved: 2/19/