as

• Flukes


  • With oral and ventral suckers (acetabulum)
  • Body is covered by an integument which often bears spines, tubercles
  • No body cavity, circulatory and respiratory organ
• Types of habitat


  • Blood fluke
  • Pulmonary or lung fluke
  • Liver or hepatic fluke
  • Intestinal fluke
• Blood fluke species


  • Schistosoma japonicum (Oriental Blood Fluke)
  • Schistosoma mansoni (Manson's Blood fluke)
  • Schistosoma haematobium (Vesical Blood Fluke)
  • Schistosoma intercalatum
  • Schistosoma mekongi
• Lung fluke species


  • Paragonimus westermani (Oriental Lung fluke)
• Liver fluke species


  • Fasciola hepatica (Sheep Liver Fluke)
  • Clonorchis sinensis (Chinese Liver Fluke, Oriental Liver Fluke)
  • Opistorchis felineus (Cat Liver Fluke)
• Intestinal fluke species


  • Fasciolopsis buski (Busk Fluke, Giant Intestinal Fluke)
  • Echinostoma ilocanum (Garrison's Fluke)
  • Heterophyes heterophyes (Von Siebold Fluke, Dwarf Fluke)
  • Metagonimus yokogawai (Yokogawa's fluke)
• Blood flukes


  • Non-hermaphroditic/Dioecious
  • Body of adult worm is not leaf like
  • Adult worms produce non-operculated eggs
  • Require only one intermediate and one definitive host
  • Infective stage is Cercaria - larva equipped with mouth, GIT & forked tail
  • Mode of transmission is through skin penetration

  
• Diagnostic stage for blood flukes

  Eggs
• Entry of blood fluke cercaria to human skin can lead to infection called SCHISTOSOMIASIS/BILHARZIASIS
• Specific habitat of blood flukes

  • Schistosoma japonicum - Superior mesenteric veins
  • Schistosoma mansoni - Inferior mesenteric veins or veins draining rectum
  • Schistosoma haematobium - Vesical veins or veins draining the urinary bladder
• Characteristics of blood flukes

  • Schistosoma japonicum - Integument smooth, 6-8 testes in males, 50-100 eggs in uterus
  • Schistosoma mansoni - Integument with coarse tuberculations, 8-9 testes in males, 1-4 eggs in uterus
  • Schistosoma haematobium - Integument with fine tuberculations, 4-5 testes in males, 20-30 eggs in uterus

  
• Largest adult blood fluke

  Schistosoma japonicum
• Smallest adult blood fluke

  Schistosoma haematobium
• Genus of snail intermediate host for blood flukes

  • Schistosoma japonicum - Oncomelania quadrasi
  • Schistosoma mansoni - Biomphalaria, Planorbis and Tropicorbis
  • Schistosoma haematobium - Bulinus, Physopsis

  
• Characteristics of blood fluke eggs

  • Schistosoma japonicum - Non-operculated with minute lateral spine, 70-105 x 50-80 um
  • Schistosoma mansoni - Non-operculated with distinct lateral spine, 45-70 x 140-180 um
  • Schistosoma haematobium - Non-operculated with distinct terminal spine, 112-170 x 40-70 um

  
• Eggs of schistosomes are always non-operculated
• Adult worms of schistosomes are always dioecious

  
• Developmental stages of schistosomes

  • Egg
  • Miracidium - ciliated larva released from egg
  • Sporocyst - larvae developed from miracidium
  • Cercaria - infective larva with forked tail
  • Schistosomule - cercaria that has lost its tail after entry into human skin
• Katayama fever is a hypersensitivity reaction caused by migration of schistosomula to appropriate blood vessel
• Schistosoma mekongi


  Species discovered in Mekong River, eggs similar to S. japonicum but smaller
• Schistosoma intercalatum


  Eggs same as S. haematobium but with equatorial/central bulge, eggs in feces not urine
• Faust Maloney egg hatching technique


  Diagnostic test for schistosomiasis
• Circum-oval precipitin test


  Diagnostic test for schistosomiasis

  
• Lung, liver and intestinal flukes

  • Hermaphroditic/monoecious
  • Adult worms are leaf-like, non-segmented but still equipped with oral and ventral suckers
  • Adult worms produce operculated eggs
  • Heteroxenous, requiring at least 2 intermediate hosts & 1 definitive host
  • Metacercaria is the infective stage
  • Mode of transmission is through ingestion
• Diagnostic stage for lung, liver and intestinal flukes

  Eggs
• Distinct features of adult lung, liver and intestinal flukes

  • Clonorchis sinensis - Assumes a coffee bean appearance
  • Opistorchis felineus - Appears as if it has shoulders because of the CEPHALIC CONE
  • Paragonimus westermani - With branched testes, ovaries & intestina ceca
  • Fasciola hepatica - Appears like F. hepatica but NO CEPHALIC CONE, intestinal ceca is unbranched
  • Echinostoma ilocanum - Equipped with 3rd sucker -GENITAL SUCKER/GONOTYL
  • Heterophyes heterophyes - Closely resembles H. heterophyes but slightly larger and with no genital sucker
  • Clonorchis sinensis vs Opistorchis felineus - C. sinensis with granular vitellaria & dendritic testes, O. felineus with transverse vitellaria & lobed testes
• Genus/species of 1st and 2nd intermediate hosts

  • Paragonimus westermani - 1st IH: Brotia asperata, 2nd IH: Fresh Mountain crabs
  • Fasciola hepatica - 1st IH: Lymnea philippinensis, 2nd IH: Watercress, Kangkong
  • Fasciolopsis buski - 1st IH: Segmentina spp., Hippeutis spp, 2nd IH: Water caltrop, Water chestnut, Bamboo shoots
  • Clonorchis sinensis - 1st IH: Alocinma spp., Bulimus spp. and Parafossarulus spp, 2nd IH: Cyprinoid Fishes
  • Opistorchis felineus - 1st IH: Bithynia spp., 2nd IH: Cyprinoid Fishes
  • Echinostoma ilocanum - 1st IH: Gyraulus convexiusculus and Hippeutis umbilicalis, 2nd IH: Kuhol, Susong Pampang
  • Heterophyes heterophyes - 1st IH: Pirenella spp., Cerithidea spp., 2nd IH: Mugil, Tilapia, Arius manilensis
  • Metagonimus yokogawai - 1st IH: Semisulcospira spp., Thiara spp., Hua spp., 2nd IH: Salmonoid Fishes, Cyprinoid Fishes