PARA LAB SEMI

• Trematodes


  Also called FLUKES, belong to Phylum Platyhelminthes "Flatworms" (together with cestodes), leaf-like adults
• Trematodes


  • Habitat: Blood, Lungs, Liver, Intestines and Pancreas
  • All monoecious except Schistosoma species
  • Possess spines and tuberculations (protruding structures)
  • All possess two suckers except Heterophyes heterophyes (oral sucker for nutrition, ventral sucker for attachment, H. heterophyes has 3 suckers including genital sucker "gonotyl")
  • Eggs are the diagnostic stage, operculated (has a lid-like structure to allow larva to exit) except Schistosoma (non-operculated, already embryonated once released)
• Blood Fluke life cycle

  1. Cercarial/skin penetration "Swimmer's itch"

  2. Fork-tailed cercaria with lytic enzymes breaks down skin to penetrate

  3. Adult worms reproduce, producing eggs deposited in blood vessels, eggs may go to liver, intestinal tract, and urinary bladder, recovered in stool or urine

  4. Male shorter and thick, female longer and thin
• Schistosoma japonicum


  Oriental Blood Fluke, habitat in superior mesenteric vein of small intestine, intermediate host Oncomelania hupensis quadrasi, largest adult stage, ova with recurved hook or knob (smallest), Katayama Syndrome/Fever 1-3 months after initial phase
• Schistosoma mansoni


  Manson's Blood Fluke, habitat in inferior mesenteric vein of the colon, intermediate host Biomphalaria, smallest adult stage, male with prominent/coarse tuberculation, ova elliptical with lateral spine, associated with Spinal cord schistosomiasis
• Schistosoma haematobium


  Vesical Blood Fluke, habitat in vesical, prostatic, uterine plexuses of the venous circulation, intermediate host Bulinus, male with fine tuberculation, ova elliptical with terminal spine, causes Urinary Bilharziasis, Egyptian Hematuria, linked with bladder carcinoma
• Diagnosis of Blood Flukes

  1. Rectal snips (most sensitive and invasive)

  2. Rectal biopsy
• Lung Fluke - Paragonimus westermani


  Oriental Lung fluke, 1st intermediate host Antemelania snails, 2nd intermediate host Sundathelphusa philippina freshwater/mountain crabs, infective stage metacercaria, mode of transmission ingestion of uncooked/undercooked crabs with metacercaria, cysteine proteases involved in metacercarial excystment and tissue invasion, early stages asymptomatic, heavy infections cause dry cough/chronic cough, blood-stained or rust-colored sputum (fishy odor), can go to heart and brain (erratic Paragonimiasis)
• Paragonimus westermani adult

  • Reddish brown, coffee bean-shaped, rounded anteriorly and slightly tapered posteriorly, found in pairs or threes in fibrotic capsules of the lung, firmly attached to lung tissue, presence of spines on tegument, wavy intestinal ceca
• Intestinal Fluke - Fasciolopsis buski


  Giant Intestinal Fluke, final host humans, habitat duodenum and jejunum, infective stage metacercaria, mode of transmission ingestion of encysted metacercariae from aquatic plants, 1st intermediate host Segmentina or Hippeutis snails, 2nd intermediate host water plants like Trapa bicornis, Eliocharis tuberosa, Ipomea aquatica, Ipomea obscura, Nymphaea lotus
• Fasciolopsis buski ova

  • LARGE and operculated, unembryonated, oval shaped, 20-75 mm length, 8-20 mm width

  
• Intestinal Fluke - Echinostoma ilocanum

  Garrison's Fluke, final host humans, reservoir hosts dogs, cats, rats, pigs, habitat small intestine, 1st intermediate host Gyraulus convexiusculus and Hippeutis umbilicalis snails, 2nd intermediate host Pila luzonica (kuhol) and Vivipara angularis (susong pampang) snails, infective stage metacercaria, mode of transmission ingestion of metacercariae encysted in snails
• Echinostoma ilocanum adult

  • Reddish gray, tapers at posterior end, elongated, characteristic circumoral disk with 49-51 collar spines (aids in attachment), testes deeply bilobed and in tandem, simple and unbranched intestinal ceca

  
• Intestinal fluke - Echinostoma ilocanum


  • Reddish gray, tapers at the posterior end (thinner)
  • Elongated
  • Characteristic circumoral disk (with spines surrounding the oral sucker) - 49-51 collar spines, aids in attachment
  • Bloody diarrhea attributed to this
  • Testes deeply bilobed and in tandem
  • Intestinal ceca are simple and unbranched
• Heterophyid worms


  Intestinal flukes
• Heterophyid worms - adult

  • Elongated, oval, or pyriform (pear-shaped)
  • Very small
  • Tegument: fine scale-like spines
  • Third sucker (gonotyl) seen in H. heterophyes
  • Testes arrangement is varied (depends on species)
  • Ovary is globular or lobed
  • Short life span (<1 year)
  • Metagonimus yokogawai: Testes large and oval

  
• Fasciola spp. (Liver flukes)


  Parasites of the biliary passages of the liver
• Eggs reported as Fasciola egg
• Fasciola hepatica


  Sheep Liver fluke or Temperate Liver fluke, found in cold and temperate countries, also found in sheep and herbivores
• Fasciola gigantica


  Tropical Liver fluke, more common in tropical countries
• Diagnosis of Fasciola infection

  • Stool exam (Look for Ova)
  • Radiography
  • Hepatic sonography
  • Endoscopic retrograde cholangiopancreatography
• Fasciola hepatica - adult


  • Large broad, flat body
  • Cephalic cone and prominent shoulders
  • Intestinal ceca highly branched
  • Testes (2): highly branched, no longer described because highly branched
  • Ovary: dendritic
  • Uterus: coiled and short
• Fasciola gigantica - adult


  • Longer but narrower (slender)
  • Shorter cephalic cone and less developed shoulders
  • Testes: branching
• Fasciola spp. - ova


  • Large, ovoidal
  • Brownish
  • Operculated
  • Immature when released
• Clonorchis and Opisthorchis


  Liver flukes, parasites of the bile duct and gall bladder
• Prevalent in South East Asia, China, Japan, and Korea (fish-eating countries)
• Final hosts of Clonorchis and Opisthorchis

  • Humans
• Reservoir hosts of Clonorchis and Opisthorchis

  • Cats
  • Dogs
  • Pigs
  • Other mammals (fish-eating animals)
• 1st intermediate hosts of Clonorchis sinensis

  • Parafossarulus
  • Bulinus
  • Semisulcospira
  • Alocinma
  • Thiara
  • Melanoides
• 2nd intermediate hosts of Clonorchis and Opisthorchis


  • Cyprinoid freshwater fish
• Clonorchis sinensis is the most important liver fluke of man
• Clonorchis sinensis - adult


  • Flat, transparent, elongated, rounded posteriorly
  • Attenuated anteriorly, spatulate in appearance
  • Deeply branched testes arranged in tandem
  • Lobed ovaries
  • Intestinal ceca are simple and unbranched
  • Largest oral sucker among other flukes
  • Vitellaria: found in the middle third of the body (at the level of uterus)

  
• Opisthorchis felineus - adult


  • Reddish brown, paired, lobate testes arranged obliquely in tandem
• Opisthorchis viverrini - adult


  • Deeply lobulated ovaries and testes
• Clonorchis and Opisthorchis - ova

  • Yellowish brown, ovoid
  • Distinct convex operculum (Presence of opercular shoulder)
  • Presence of abopercular protuberance (opposite operculum)
  • Old fashioned bulb or pitcher shape
  • Similar egg: H. heterophyes (but Heterophyes does not have the abopercular protuberance)
  • Indistinguishable from other species
• Diagnosis of Clonorchis and Opisthorchis infection

  • Stool exam
  • Cholangiography
  • Radiological features of biliary clonorchiasis (Arrow-head sign)
• Final hosts of Dicrocoelium dendriticum

  • Herbivores (ruminents)
  • Humans (accidental hosts)
• Intermediate hosts of Dicrocoelium dendriticum


  • 1st: Cionella lubrica (snail)
  • 2nd: Formica fusca (ants)
• Ingestion of ants containing metacercaria


  Leads to Dicrocoelium dendriticum infection
• Diagnosis of Dicrocoelium dendriticum infection

  • Stool exam