Fasciola hepatica is a fluke parasite referred to as Sheep liver fluke causing a disease known as Fascioliasis.The mode of transmission of infection to humans is through ingestion of raw infected water plants.The fluke is found worldwide, particularly in areas in which sheep and cattle are raised. Sheeps are natural host for the completion of the Fasciola hepatica life cycle and humans serve as accidental hosts.
Habitat of Liver flukes
- The adult worm leaves in the bile duct of sheep, goat, cattle
- Egg are recovered or found In faeces
- All the larva stages are found in fresh water snail
- Metacercariae are found on water vegetations
Morphology of Fasciola hepatica
- The adult Fasciola hepatica is a fleshy, flat, leaf-like grey brown in colour.
- It measures approximately 3 by 1 cm ( 30 mm by 12mm) and has a cone shaped prominent two “shoulders” with branched intestinal caeca.
- It’s genital pore are anterior to the ventral sucker
- Tests in tendem and highly branched and fan-shaped ovary with no seminal receptacle
- Fasciola hepatica eggs is non embryonated and measures 128 to 150 µm by 60 to 90 µm.
- Oval with rounded poles and smooth shell with a double line and a marked or distinct operculum at one pole.
- It is yellow to dark brown in color and bile stained with an oblong undeveloped miracidium and a clear granular nuclei inside
Life Cycle of Fasciola hepatica
Sheep, cattle, man and other herbivorous animals are definitive host of fasciola hepatica while species of Lymnaea snails are intermediate hosts.
Immature eggs are excreted in the faeces. These egg then hatches in fresh water and develops into miracidium.The miracidium enter snails of the genus Lymnaea. In the snail, the miracidium then develop into sporocyst and produces generation of rediae and then cercariae. The cercaria is shaded from the snail host and undergoes encystation on water vegetation to become metacercariae.
Man acquires infection by eating wild watercress or other water vegetation on which metacercariae have encysted.
Following the ingestion of raw infected water plants,the metacercariae migrates to the duodenum and excyst.The young flukes then migrate in to the peritoneal cavity. They reach the bile ducts of the liver by penetrating through the liver capsule then become adult worms.
Clinical Symptoms of Fasciola hepatica
People infected with Fasciola hepatica usually experiences symptoms caused due to the presence and attachment of the adult worm to the biliary tract.
These symptoms include
- fever, and chills
- pains in the liver area of the body due to damage of tissue, some of which may extend to the shoulders and back.
- Also elevated eosinophils (Eosinophilia) causes of esinophilia is due to the presence of the parasite (eosinophils and parasites)
- liver tenderness
- digestive discomfort are sometimes seen.
- This may also result to biliary obstruction
Laboratory Diagnosis of fasciola hepatica
- Eggs are usually recovered in stool mostly during chronic infections
- Eggs can also be recovered in aspirates & in bile
- Serological diagnosis can also be used by testing serum for antibodies especially during early stages of infection when the immature flukes are migrating through the liver and causing serious symptoms but not yet producing eggs
If the eggs are found in stool it is necessary to confirmed whether they are present due to a Fasciola infection or from eating animal liver containing fascioliasis eggs (false fascioliasis)
False Fascioliasis occurs due to the ingestion of animal liver already containing Fasciola hepatica egg, with the passage of eggs in stool and is sometimes mistaken for actual fascioliasis.Therefore, to rule out the difference,the patient is place on liver free diet for at least three to four days and rediagnose to find eggs in stool.
In case egg is seen in stool,this confirm a true infection.
keep the patient on liver free diet for three days. If egg is found in repeated exam the infection is true.
fluke or fluke worm treatment treatment
- The drug or medication of choice is Praziquantel for the treatment of Fascioliasis.It can also be giving to animals like praziquantel for dogs(praziquantel dog wormer)
- Bithionol is also an acceptable alternative drug
- Triclabendazole is more effective
Prevention and Control
The primary prevention and control measures for the eradication of these liver flukes causing Fascioliasis include
- Avoiding the human consumption of raw water plants or contaminated water
- Practising proper disposal of human waste products.
- Avoid using faeces as fertilizer mostly in tropical and underdeveloped countries
- Main good sanitation