TREMATODES

• Trematodes


  • Leaf-like and hermaphroditic (except blood flukes: Dioecious)
  • Operculated eggs (except blood flukes: Spines)
  • Infective stage: Metacercaria (except blood flukes: Cercaria)
  • MOT: Ingestion (except blood flukes: direct penetration)
  • Requires TWO intermediate host (except blood flukes: ONE only)
  • Adult flukes generally have TWO suckers: Oral and ventral
  • Simple digestive and genital tract
  • First intermediate host (IH) for all: Snail

  
• Life cycle of trematodes

  1. Eggs

  2. Larval stage (Miracidium, Sporocyst, Rediae, Cercaria, Metacercaria)

  3. Adult

  
• Intermediate hosts


  • 1st: Snails
  • 2nd: Fish, Crab, Plant/Vegetation, Snail
• Specimen of choice for laboratory diagnosis

  Stool, Duodenal drainage, Rectal biopsy, Sputum, Concentrated urine
• Tests for laboratory diagnosis

  • DFS, Microscopy, Serologic tests (ELISA)
• Fasciolopsis buski


  Large intestinal fluke

  
• Ingestion of raw infected water plants

  Fasciolopsis
• Specimen of choice for Fasciolopsis buski

  • Stool
• Tests for Fasciolopsis buski


  • Enterotest, ELISA, Gel diffusion, Detection of parasite eggs in stool specimen

  
• Pathogenesis of Fasciolopsis buski


  • Inflammation and ulceration at the site of worm attachment; increase mucus secretion and minimal bleeding
  • Gland abscesses are occasionally formed in the mucosa
  • Heavy infection = Intestinal obstruction

  
• Prevention and control of Fasciolopsis buski

  • Proper human fecal disposal
  • Sanitation practices
  • Controlling the snail population
  • Avoiding consumption of raw water plants or contaminated water
• 2nd intermediate hosts for Fasciolopsis buski


  • Water caltrop (Trapabicornis)
  • Water chestnut (Eliocharis tuberosa)
  • Morning glory/kangkong (Ipomea obscura)
  • Lotus (Nymphaea lotus)
• Fasciola hepatica


  Sheep liver fluke
• Fasciola gigantica


  Giant liver fluke
• Ingestion of encysted metacercariae from aquatic plants or drinking of contaminated water

  Fasciola hepatica and Fasciola gigantica
• Specimen of choice for Fasciola hepatica and Fasciola gigantica


  • Stool, Duodenal contents, Bile
• Tests for Fasciola hepatica and Fasciola gigantica


  • Det. of eggs in stool, duodenal contents, or bile
  • Surgical exploration, treatment, or autopsy (Recovery of adult worms)
  • Immunologic methods (ELISA, Western blot)
  • Radiological examinations (CT)
  • Sonography (biliary lesions)

  
• Pathogenesis of Fasciola hepatica and Fasciola gigantica

  • ACUTE STAGE: dyspepsia, fever, abdominal pain (right upper quadrant)
  • CHRONIC PHASE: Obstruction and inflammation in the biliary epithelium
• Treatment for Fasciola hepatica and Fasciola gigantica

  • Triclabendazole
  • Bithionol
• Prevention and control of Fasciola hepatica and Fasciola gigantica


  • Thorough washing or cooking of vegetables, and boiling of water
  • Control measures include elimination of the snail intermediate host through the application of copper sulfate, and killing the parasite in the reservoir host by chemotherapy

  
• 1st intermediate host for Fasciola hepatica and Fasciola gigantica


  • Snail (family Lymnaeidae)
  • In the Philippines: L. philippinensis, L. auricularia rubiginosa
• 2nd intermediate host for Fasciola hepatica and Fasciola gigantica


  • Morning glory/kangkong (Ipomea obscura)
  • Watercress (Nasturtium officinale)

  
• Clonorchis sinensis


  Chinese liver fluke
• Ingestion of undercooked fish

  Clonorchis sinensis

  
• Specimen of choice for Clonorchis sinensis

  • Stool, Duodenal aspirates

  
• Tests for Clonorchis sinensis

  • Detection of parasite eggs in stool or duodenal aspirates
  • Enterotest
  • Surgery or autopsy (Adult worm)

  
• Pathogenesis and clinical symptoms of Clonorchis sinensis

  • Asymptomatic
  • Clonorchiasis: fever, abdominal pain, eosinophilia, diarrhea, etc.
  • Enlargement and tenderness of liver
• Treatment for Clonorchis sinensis

  • Praziquantel
  • Albendazole
• Prevention and control of Clonorchis sinensis


  • Proper sanitation
  • Avoid ingestion of raw foods
• Definitive hosts for Clonorchis sinensis

  • Man
  • Pig
  • Dog
  • Cat
  • Rat
• 1st intermediate host for Clonorchis sinensis

  • Snail (genus Parafossarulus, Bulinus, Semisulcospira, Thiara, Alocinma, Melanoides)

  
• 2nd intermediate host for Clonorchis sinensis

  • Majority from family Cyprinidae

  
• Heterophyid flukes


  • Heterophyes heterophyes (Von Siebold's Fluke)
  • Metagonimus yokogawai (Yokogawa's Fluke)
  • Haplorchis taichu
  • Haplorchis yokogawai
• Ingestion of contaminated undercooked fish

  Heterophyid flukes
• Specimen of choice for Heterophyid flukes

  • Stool
• Pathogenesis and clinical symptoms of Heterophyiasis/Metagonimiasis

  • Asymptomatic
  • Heavy infection: Abdominal pain and discomfort, chronic mucous diarrhea, eosinophilia
  • Granulomas in other areas of the body (e.g., heart, brain)
• Prevention and control of Heterophyid flukes

  • Avoid ingestion of raw/undercooked fish
• Definitive host for Heterophyid flukes

  • Man
  • Fish-eating mammals

  
• 1st intermediate host for Heterophyid flukes

  • Snail (freshwater, brackish water, or marine species)

  
• 2nd intermediate host for Heterophyid flukes

  • Fish (fresh/brackish water species)