Heterophyid Flukes

• Heterophyid Flukes

  General Characteristics

  • Small intestinal flukes found in the villi of the small intestine.
  • Includes:
  • Heterophyes heterophyes (Intestinal Fish Fluke)
  • Metagonimus yokogawai (Yokogawa Fluke)
  • Haplorchis taichui (Minute Intestinal Fluke)
  • Acquired through ingestion of raw/undercooked freshwater or brackish water fish.
• Life Cycle

  • Eggs (embryonated) are released in feces.
  • Snail IH (1st IH) ingests eggs → Miracidium hatches inside IH → Develops into sporocyst → redia → cercaria.
  • Cercaria is released from the snail, penetrates fish epithelium (2nd IH), and encysts as metacercaria in muscle tissue.
  • Final host ingests infected fish → Metacercaria develops into an adult in the small intestine.
• Laboratory Diagnosis

  • Stool examination: Detection of operculated eggs.
  • Definitive diagnosis: Based on recovery of adult flukes after anthelmintic therapy.
• Treatment & Prevention

  • DOC: Praziquantel (20-25 mg/kg orally, 3x a day).
  • Prevention:
  • Avoid eating raw/undercooked freshwater fish in endemic areas.
  • Practice proper fecal disposal and basic hygiene/sanitation.
• HETEROPHYIDS: CLINICAL MANIFESTATIONS

  • Main symptoms are diarrhea and colicky abdominal pain.
  • Migration of eggs to heart, causing potentially fatal myocardial and valvular damage.
  • Adult forms can migrate to other organs (ex. Brain).
  • Can cause neurological symptoms such as transverse myelitis and loss of sensory/motor functions.
• Egg Morphology of Heterophyid Flukes

  • H. heterophyes, M. yokogawai, and C. sinensis eggs are indistinguishable
  • Light brown, 20-30µm x 15-17µm
  • Operculated with shoulders
  • Miracidium present inside egg
  • Reported as "presence of heterophyid egg"
• Metagonimus & Heterophyes vs. Clonorchis

  • M. yokogawai and H. heterophyes have less distinct shoulders
  • M. yokogawai and H. heterophyes eggs lack a small terminal knob