Fasciola hepatica - Clinical Manifestation, Complication, Prognosis, Reservoir

Clinical manifestations of Fasciola hepatica

The clinical manifestations of Fasciola hepatica include chronic fascioliasis and acute fascioliasis with half of the infections being sub-clinical. The incubation period may range from 4 months to 6 months.

Acute fascioliasis

• acute fascioliasis is caused by the migration of Fasciola hepatica larvae through the liver parenchyma

• common symptoms include fever, abdominal pain, hepatomegaly, eosinophilia

  * abdominal pain is either generalized or if localized limited to the right costal region

• less common symptoms are nausea, vomiting, diarrhoea, anorexia, jaundice, and change in bowel habits while malaise and weight loss are seen in one-third of patients infected with liver fluke

Chronic fascioliasis

• chronic fascioliasis is caused by adult worms residing in common and bile duct

• the symptoms – which are highly variable – include irregular fever, anaemia, eosinophilia

• due to intermittent biliary obstruction and inflammation, hepatobiliary manifestations can occur – which are colicky pain, jaundice, secondary bacterial infections

• in children, additional syndromes include abdominal pain and pancreatitis

• rare symptoms are urticaria, wheezing, subcutaneous nodules

• in chronic cases, ectopic infections may involve organs such as skin, lungs, heart, brain, eye, and intestine

Complications of Fasciola hepatica infection

In children, complications of Fasciola hepatica infection include severe anaemia, ascending cholangitis, and pancreatitis.

Fascioliasis in Lebanon (halzoun) and Sudan (Marrerra), caused by the consumption of raw livers of cattle and sheep as a delicacy, results in living liver flukes invading and attaching to the posterior pharyngeal wall. Complications in such cases include severe pharyngitis, laryngeal oedema, dysphagia, and airway obstruction.

Prognosis of Fasciola hepatica infection

The prognosis of Fasciola hepatica is good with treatment as it shortens the course of infection. Acute fascioliasis is self-limiting.

Reservoir, Source of Fasciola hepatica

The main source of Fasciola hepatica infection is the secondary intermediate host - watercress (Nasturtium officinale), water lettuce, mint, khat, and aquatic vegetation harbour the infective larvae stage (metacercariae).

The key reservoir is the sheep followed by castles and other herbivores. Since man is the accidental host, the infection is maintained in nature between sheep, cattle, and amphibian snails.