Fasciola spp.

• Fasciola hepatica & Fasciola gigantica

  Common Name

  • Fasciola hepatica – Common/Sheep Liver Fluke
  • Fasciola gigantica – Giant Liver Fluke

  Disease

  • Fascioliasis / Fasciolosis

  Habitat

  • Liver, biliary passages of humans and herbivorous mammals

  Intermediate Hosts

  • 1st Intermediate Host: Pulmonate freshwater snails (Lymnaea bulmoides, L. tomentosa, Fossaria, Pseudosuccinea, Galba truncatula)
  • 2nd Intermediate Host: Aquatic plants (Ipomoea aquatica [Kangkong], Nasturtium officinale [Watercress])

  Final Host

  • Humans, cattle, sheep, goats

  Diagnostic Stage

  • Unembryonated eggs in feces
• Fasciola hepatica & Fasciola gigantica cont.

  Infective Stage

  • Metacercariae in aquatic vegetation

  Mode of Transmission

  • Ingestion of metacercariae in aquatic plants

  Treatment

  • Drug of Choice: Triclabendazole
  • Alternative: Bithionol

  Additional

  • Lifespan: 9-13 years
  • Geographic Distribution: Primarily in African countries
  • Fascioliasis is classified as a Neglected Tropical Disease (NTD)
• Egg Characteristics

  • Largest trematode egg in human infection (130-150µm x 63-90µm)
  • Thin-shelled with distinct operculum
  • Presence of abopercular knob
  • Ovoid with undeveloped miracidium
  • Resembles a hen’s egg
• Larva Characteristics

  • Metacercariae measure 0.2mm in diameter
  • If formed in water, can survive up to a year
  • If formed in aquatic vegetation, survives only a few weeks
• Adult Characteristics

  Fasciola hepatica

  • Size: 3cm x 1.3cm
  • Shape: Leaf-like, pointed posterior, wide anterior
  • Cephalic cone present
  • Two prominent shoulders
  • Color: Pinkish, appears brownish due to bile
  • Reproductive Organs:
  • Testes and ovary are tubular and highly branched
  • Uterus is convoluted and wide
  • Intestinal Ceca: Smaller, with inverted Y-shaped medial branches
• Adult Characteristics

  Fasciola gigantica

  Size: 7.5cm x 1.5cm (longer than F. hepatica)

  Shoulders: Less prominent

  Intestinal Ceca: Larger, with T or Y-shaped medial branches
• Fasciola: Life Cycle

  1. Immature eggs are discharged in the biliary ducts into the stool.
  2. Eggs become embryonated in freshwater over ~2 weeks, then release miracidia that seek intermediate hosts.
  3. Miracidia develop in snail IH, turning into cercariae, which encyst as metacercariae in vegetation.
  4. Animals are infected by ingesting contaminated vegetation.
  5. After ingestion, metacercariae excyst in the duodenum, penetrate the intestinal wall, and enter the peritoneal cavity.
  6. Immature flukes migrate through the liver parenchyma into the biliary ducts, where they mature and produce eggs.
• Fasciola: Clinical Manifestations

  Acute Phase

  • Lasts 2-4 months
  • Migration to liver causes symptoms proportionate to worm burden
  • Symptoms: Fever, abdominal pain, diarrhea, eosinophilia

  Chronic Phase

  • Begins when worms reach the bile ducts
  • Symptoms: Intermittent pain, jaundice, anemia
  • Heavy worm burdens → Extensive inflammation, epithelial hyperplasia, fibrosis
  • Severe cases: Bile duct obstruction
• Fasciola: Clinical Manifestations cont.

  Ectopic Fascioliasis

  • Extrahepatic involvement
  • Tender, migrating nodules up to 6cm
  • Related to migration, elevated eosinophilia
  • Sites: Ocular, cutaneous, subcutaneous

  Halzoun Disease

  • AKA Snail disease
  • Buccopharyngeal infection in the Middle East
  • Contracted from eating raw lamb liver, infected goat meat
  • Symptoms: Edema in soft palate, larynx, pharynx → Dyspnea, asphyxia
• Fasciola: Laboratory Diagnosis

  Basic Techniques

  • Stool Examination (Egg ID via Microscopy)
  • Direct Fecal Smear (DFS)
  • Kato-Katz / Thick Smear
  • Concentration techniques (e.g., FECT)

  Specialized Techniques

  • Antibody Test (Used in early invasive stages before eggs appear in stool)
  • Enterotest
  • ELISA / FAST-ELISA
  • Gel Diffusion
  • Ultrasonography
• Fasciola: Treatment & Prevention

  Treatment

  • Drug of Choice (DOC): Triclabendazole
  • Alternative: Bithionol

  Prevention

  • Periodic examination & treatment of livestock
  • Thorough washing & cooking of vegetables
  • Health education
  • Snail control

  Fascioliasis Control in the Philippines

  • DOH: Food and Waterborne Diseases (FWBD) Prevention and Control Program
  • DOA: National Fascioliasis Control Program
• Image of eggs Fasciola spp.

  Indistinguishable eggs along with Fasciolopsis buski