Trematodes Flashcards
aka FLUKES
TREMATODES
appearance of adult TREMATODES
Leaf-like
TREMATODES: monoecious or dioecious
Monoecious
Infective stage of trematodes
Metacercaria (last larval stage of trematodes)
Means of trematodes in attaching themselves to the host
2 suckers (oral and ventral/acetabulum)
2 suckers of trematodes
Oral sucker
Ventral sucker (acetabulum)
How many suckers does trematodes have? Is there an exception?
2 suckers (oral and ventral/acetabulum)
Exception: Heterophyes heterophyes = 3rd sucker: genital sucker/gonotyl
No. and type of host required by trematodes
2 INTERMEDIATE HOSTS
1st IH: Snail
2nd IH: Fish, crabs, vegetation, snail
General MOT of trematodes
Ingestion of the 2nd intermediate host infected with Metacercaria
Give some habitats of trematodes
Liver
Intestines
Pancreas
Lungs
describe the egg stage of trematodes
Eggs – has operculum (lid-like; allows exit of larva from the egg when they hatch)
lid-like structure that allows the exit of larva from the egg when they hatch
operculum
larval stage of trematodes
(5 sub-stages) – “My Sister Rent a Car for Me”
* Miracidium
* Sporocyst
* Redia
* Cercaria
* Metacercaria – infective stage
describe the adult stage of trematodes
Oviparous or Oviviparous
Enumerate FASCIOLIDS
- Fasciola hepatica – liver fluke
- Fasciola gigantica – liver fluke
- Fasciolopsis buski – intestinal fluke
Enumerate HETEROPHYIDS
- Clonorchis sinensis
- Opisthorchis felineus
- Heterophyes heterophyes
- Metagonimus yokogawai
Enumerate INTESTINAL FLUKES
Fasciolopsis buski
Echinostoma ilocanum
Heterophyes heterophyes
Metagonimus yokogawai
Enumerate LIVER FLUKES
Fasciola hepatica
Fasciola gigantica
Clonorchis sinensis
Opisthorchis felineus
Dicrocoelium dendriticum/ lanceolata
LUNG FLUKE
Paragonimus westermani
PANCREATIC FLUKE
Eurytrema pancreaticum
Enumerate SCHISTOSOMES / BLOOD FLUKES
Schistosoma japonicum
Schistosoma mansoni
Schistosoma haematobium
Schistosoma mekongi
Schistosoma intercalatum
aka Giant Intestinal Fluke
Fasciolopsis buski
Largest fluke parasitizing man
Fasciolopsis buski
larger than F. gigantica
Fasciolopsis buski
FINAL HOST of Fasciolopsis buski
Man
1ST IH of Fasciolopsis buski
Snails:
* Segmentina
* Hippeutis
2ND IH of Fasciolopsis buski
Vegetation:
* Water Caltrop (Trapa bicornis)
* Water Chestnut (Eliocharis tuberosa)
* Kangkong/Morning Glory (Ipomea obscura)
* Lotus (Nymphaea lotus)
* Bamboo shoots (Zizania latifolia)
Habitat of Fasciolopsis buski
Small intestine
Infective stage of Fasciolopsis buski
Metacercaria
PATHOLOGY: Fasciolopsis buski
Abdominal discomfort
Diarrhea
Edema
Lab dx of Fasciolopsis buski
Stool examination
Concentration techniques
Molecular techniques
Drug of choice for Fasciolopsis buski
Praziquantel
Adult form has:
- simple intestinal ceca
- 2 dendritic testes in tandem
- branched ovaries
Fasciolopsis buski
Egg of Fasciolopsis buski
Indistinguishable from other fasciolid ova
aka Garrison’s Fluke
Echinostoma ilocanum
Discovered by Philip Garrison among prisoners of Bilibid Prison in Manila, PH
Echinostoma ilocanum
FINAL HOST of Echinostoma ilocanum
Man
1ST IH of Echinostoma ilocanum
Snails:
* Gyraulus convexiusculus
* Hippeutis umbilicalis
2ND IH of Echinostoma ilocanum
Snails:
* Kuhol (Pila luzonica)
* Susong Pampang (Vivipara angularis)
Habitat of Echinostoma ilocanum
Small intestine
Infective stage of Echinostoma ilocanum
Metacercaria
PATHOLOGY: Echinostoma ilocanum
Abdominal discomfort
Chronic mucous diarrhea
Eosinophilia
Lab dx of Echinostoma ilocanum
Stool examination
Concentration techniques
Molecular techniques
Drug of choice for Echinostoma ilocanum
Praziquantel
Adult is described having Circumoral disk with crown of spines (49-51 spines) surrounding the oral sucker
Echinostoma ilocanum
Describe Echinostoma ilocanum egg
Germ ball egg with triangular operculum
Germ ball egg with triangular operculum
Echinostoma ilocanum egg
aka
Von Siebold’s Fluke
Heterophyid Fluke
Heterophyes heterophyes
Smallest trematode of man
Heterophyes heterophyes
Deadliest trematode (can migrate to brain, heart, spinal cord)
Heterophyes heterophyes
Heterophyes heterophyes migration to the heart (15% of the fetal heart disease)
Heterophyid myocarditis
FINAL HOST of Heterophyes heterophyes
Man
1ST IH of Heterophyes heterophyes
Snails:
* Cerithidea
* Pirenella
2ND IH of Heterophyes heterophyes
Fishes:
* Balanak (Mugil spp.)
* Tilapia (Tilapia spp.)
* Kanduli (Arius manilensis)
HABITAT of Heterophyes heterophyes
Small intestine
INFECTIVE STAGE of Heterophyes heterophyes
Metacercaria
PATHOLOGY: Heterophyes heterophyes
Abdominal pain
Mucous diarrhea
Ulceration of intestinal wall
Lab dx for Heterophyes heterophyes
Stool examination
Concentration techniques
Molecular techniques
Drug of choice for Heterophyes heterophyes
Praziquantel
Adult has:
- genital sucker surrounding genital pore
- 3rd sucker: genital sucker (gonocyte/gonotyl)
Heterophyes heterophyes
Old-fashioned light bulb egg
Heterophyes heterophyes
Metagonimus yokogawai
Different characteristic from other heterophyids: NO protuberance at the abopercular end
Old-fashioned light bulb egg of Heterophyes heterophyes and Metagonimus yokogawai
how do you differ M. yokogawai egg with H. heterophyes
M. yokogawai: thinner shell (still not a basis for differentiation)
aka Yokogawa’s Fluke
Metagonimus yokogawai
1ST IH of Metagonimus yokogawai
Snails:
* Semisulcospira
* Thiara
* Hua
2ND IH of Metagonimus yokogawai
Fishes:
* Salmonoid
* Cyprinoid
Habitat of Metagonimus yokogawai
Small intestine
Infective stage of Metagonimus yokogawai
Metacercaria
PATHOLOGY: Metagonimus yokogawai
Abdominal pain
Mucous diarrhea
Ulceration of intestinal wall
Lab dx for Metagonimus yokogawai
Stool examination
Concentration techniques
Molecular techniques
Drug of choice for Metagonimus yokogawai
Praziquantel
Adult is:
Pyriform-shaped
Scaly spines
NO gonotyl
Metagonimus yokogawai
Describe the egg of Metagonimus yokogawai
Old-fashioned light bulb
Describe the egg of Heterophyes heterophyes
Old-fashioned light bulb
Describe the adult form of Fasciolopsis buski
Has simple intestinal ceca
2 dendritic testes in tandem
Branched ovaries
Describe the adult form of Echinostoma ilocanum
Circumoral disk with crown of spines (49-51 spines) surrounding the oral sucker
No. of spines of Echinostoma ilocanum
49-51 spines
Describe the adult form of Heterophyes heterophyes
Has genital sucker surrounding genital pore
3rd sucker: genital sucker (gonocyte/gonotyl)
Describe the adult form of Metagonimus yokogawai
Pyriform-shaped
Scaly spines
NO gonotyl
Intestinal fluke with fishes as their 2nd IH
Heterophyes heterophyes
Metagonimus yokogawai
Intestinal fluke with snails as their both 1ST and 2ND IH
Echinostoma ilocanum
Intestinal fluke with vegetation as their 2ND IH
Fasciolopsis buski
aka
Sheep Liver Fluke
Temperate Liver Fluke
Fasciola hepatica
Natural/final host of Fasciola hepatica
Sheep
1st IH of Fasciola hepatica
Snails:
* Lymnea philippinensis
* Lymnea auricularia rubiginosa
Accidental host of Fasciola hepatica
Man
2nd IH of Fasciola hepatica
Vegetations:
* Kangkong (Ipomea obscura)
* Water cress (Nasturtium officinale)
Habitat of Fasciola hepatica
Liver parenchyma, gall bladder
Infective stage of F. hepatica
Metacercaria
Pathology of F. hepatica
Fascioliasis / sheep liver rot
Liver atrophy
Pharyngeal suffocation
result of the temporary lodgment of F. hepatica in pharynx
Pharyngeal suffocation
Pharyngeal suffocation term originated from Lebanon
Halzoun
Pharyngeal suffocation term originated from Sudan
Mararra
Lab dx for F. hepatica
Stool examination
Liver biopsy
PCR
Drug of choice for F. hepatica
Bithionol
Triclabendazole
Adult form:
- With cephalic cone
- Well-developed shoulder
Fasciola hepatica
Adult form:
- Larger than F. hepatica
- Shorter cephalic cone
- Less developed shoulder
Fasciola gigantica
describe larval stage of both F. hepatica and gigantica
ALL STAGES PRESENT
with Hen’s egg shape
ALL FASCIOLIDS EGG
Describe F. hepatica adult
With cephalic cone
Well-developed shoulder
Describe F. gigantica adult
Larger than F. hepatica
Shorter cephalic cone
Less developed shoulder
describe fasciolid eggs
- Large
- Operculated
- Unembryonated
- Yellowish-brown
aka
Giant Liver Fluke
Tropical Liver Fluke
Fasciola gigantica
Largest liver fluke
Fasciola gigantica
Natural/final host of Fasciola gigantica
Local cattle, herbivores
Accidental host of Fasciola gigantica
Man
1ST IH of Fasciola gigantica
Snails:
* Lymnea philippinensis
* Lymnea auricularia rubiginosa
2ND IH of Fasciola gigantica
Vegetations:
* Kangkong (Ipomea obscura)
* Water cress (Nasturtium officinale)
Habitat of Fasciola gigantica
Liver parenchyma, gall bladder
Infective stage of Fasciola gigantica
Metacercaria
Pathology of Fasciola gigantica
Fascioliasis / sheep liver rot
Liver atrophy
Pharyngeal suffocation
Lab dx for Fasciola gigantica
Stool examination
Liver biopsy
PCR
Drug of choice for Fasciola gigantica
Bithionol
Triclabendazole
aka
Oriental Liver Fluke
Chinese Liver Fluke
Clonorchis sinensis
Most important liver fluke of man
Clonorchis sinensis
Parasite that is a potential carcinogen
Clonorchis sinensis
Natural/final host of Clonorchis sinensis
Man and other fish-eating vertebrae
1ST IH of Clonorchis sinensis
Snails:
* Parafossarulus
* Bulinus
* Semisulcospira
* Alocinma
* Thiara
* Melanoides
2ND IH of Clonorchis sinensis
Fishes:
* Cyprinidae
Habitat of Clonorchis sinensis
Liver parenchyma
Gall bladder
Pancreatic duct
Infective stage of Clonorchis sinensis
Metacercaria
pathology of Clonorchis sinensis
- Bile duct obstruction
- Periductal fibrosis
- Gallbladder & liver carcinoma
- Liver dysfunction
Disease state mostly caused by C. sinensis
Gallbladder & liver carcinoma
(Hepatocellular carcinoma, Cholangiocarcinoma)
caused by C. sinensis; occurs on severely infected px over a long time period
Liver dysfunction
Lab dx for Clonorchis sinensis
Stool Exam
Serologic tests (ELISA, EIA)
Molecular tests (PRC)
Drug of choice for Clonorchis sinensis
Praziquantel
Albendazole
Describe the morphology of adult Clonorchis sinensis
GENERAL TO HETEROPHYIDS: Leaf-like with transparent tegument, has Vitellaria in the middle third of the body
SPECIFIC: 2 large, highly branched testes arranged in
tandem
Has 2 large, highly branched testes arranged in
tandem
Clonorchis sinensis
Pitcher-shaped/old-fashioned electric light bulb-shaped
ALL HETEROPHYIDS EGGS
Describe HETEROPHYIDS EGGS
- Yellowish-brown, ovoid
- Distinct convex operculum that fits to the thickened rim of the eggshell
- Thick rim located around the operculum (shoulders)
- Small, comma-shaped protuberance at the abopercular end
aka Cat Liver Fluke
Siberia Liver Fluke
Opisthorchis felineus
First described by McConnell
Opisthorchis felineus
aka Southeast Asian Liver Fluke
*Opisthorchis viverrini
Natural/final host of Opisthorchis felineus
Cats
1ST IH of Opisthorchis felineus
Snails:
* Bithynia
2ND IH of Opisthorchis felineus
Fishes:
* Cyprinidae
* Cobitidae
Habitat of Opisthorchis felineus
Liver parenchyma
Gall bladder
Pancreatic duct
Infective stage of Opisthorchis felineus
Metacercaria
Pathology of Opisthorchis felineus
Bile duct obstruction
Periductal fibrosis
Lab dx for Opisthorchis felineus
Stool Exam
Serologic tests (ELISA, EIA)
Molecular tests (PRC)
Drug of choice for Opisthorchis felineus
Praziquantel
Albendazole
Describe Opisthorchis felineus adult
GENERAL TO HETEROPHYIDS: Leaf-like with transparent tegument, has Vitellaria in the middle third of the body
SPECIFIC: Lobate testes arranged obliquely
Adult has lobate testes arranged obliquely
Opisthorchis felineus
gravid uterus/uterus filled with ova
Vitellaria
aka
Lanceolate
Lancet Fluke
Dicrocoelium dendriticum/ lanceolata
Dicrocoelium spp. responsible for human infection in West Africa
Dicrocoelium hospes
Natural/final host of Dicrocoelium dendriticum/ lanceolata
Cattle/Sheep
Man
1ST IH of Dicrocoelium dendriticum/ lanceolata
Snails:
* Cochlicopa
* Helix
* Xerolenta
* Zebrina
2ND IH of Dicrocoelium dendriticum/ lanceolata
Black Ants:
* Formica fusca
Habitat of Dicrocoelium dendriticum/ lanceolata
Liver parenchyma
Gall bladder
*Biliary passage of the liver
Infective stage of Dicrocoelium dendriticum/ lanceolata
Metacercaria
Pathology of Dicrocoelium dendriticum/ lanceolata
Cirrhosis
Liver Fibrosis
Lab dx for Dicrocoelium dendriticum/ lanceolata
Liver Biopsy
PCR
Describe the Dicrocoelium dendriticum/ lanceolata ADULT
Lancet-shaped (flattened and tapered at both ends)
Transparent
Adult is lancet-shaped (flattened and tapered at both ends) and transparent
Dicrocoelium dendriticum/ lanceolata
Describe Dicrocoelium dendriticum/ lanceolata EGG
Thick-shelled
Operculated
Deep golden brown
With thick-shelled, operculated, deep golden brown egg
Dicrocoelium dendriticum/ lanceolata
aka Oriental Lung Fluke
Paragonimus westermani
parasite common in Sorsogon
Paragonimus westermani
Habitat of Paragonimus westermani
lungs
Final host of Paragonimus westermani
Man
1st IH of Paragonimus westermani
Snails:
* Antemelania asperata (formerly Brotia asperata)
* Antemelania dactylus
2nd IH of Paragonimus westermani
Crabs: Sundathelphusa philippina (formerly Parathelphusa grapsoides)
Infective stage of Paragonimus westermani
Metacercaria
Describe Paragonimus westermani ADULT
Coffee-bean shaped
Wavy or succulent intestinal ceca
Adult is coffee-bean shaped and has wavy or succulent intestinal ceca
Paragonimus westermani
Egg has thickened abopercular end and flattened but prominent operculum
Paragonimus westermani
Egg is similar with Diphyllobothrium latum (cestode) ova
Paragonimus westermani
Describe Paragonimus westermani EGG
Thickened abopercular end
Flattened but prominent operculum
Similar with Diphyllobothrium latum (cestode) ova
Pathology of Paragonimus westermani
Paragonimiasis (Pulmonary distomiasis)
Chronic cough and hemoptysis (cough with blood); Resembles TB; caused by P. westermani
Paragonimiasis (Pulmonary distomiasis)
Lab dx for P. westermani
Sputum Examination
Stool exam (DFS)
Chest X-ray
Serodiagnosis (ELISA, IB)
Molecular Tests (PCR)
what must be observed in sputum exam to confirm P. westermani presence?
ova + Charcot-Leyden crystals (eosinophil degradation product)
may also look for adult
why is stool exam also necessary for lab dx of P. westermani?
sputum ingestion → intestines → stool
Habitat of Eurytrema pancreaticum
Pancreatic duct
Final host Eurytrema pancreaticum
Cattle/Sheep
1st IH of Eurytrema pancreaticum
Snails
2nd IH of Eurytrema pancreaticum
Ants
Grasshoppers
Mantis
Crickets
Infective stage of Eurytrema pancreaticum
Metacercaria
Describe Eurytrema pancreaticum ADULT
Ruffled margins
Describe Eurytrema pancreaticum EGG
Operculated, embryonated
Adult has ruffled margins
Eurytrema pancreaticum
Fluke with operculated and embryonated egg
Eurytrema pancreaticum
General characteristics are different from the other flukes
SCHISTOSOMES / BLOOD FLUKES
Elongated/cylindrical
DIOECIOUS trematode
SCHISTOSOMES / BLOOD FLUKES
trematode with Only 1 IH, which is SNAIL
SCHISTOSOMES / BLOOD FLUKES
IH of SCHISTOSOMES
snails
infective stage of schistosomes
Miracidia (infective stage to the snail)
Cercaria (infective stage to the final/definitive host)
infective stage of schistosomes to the snail
miracidia
infective stage of schistosomes to final/definitive host
cercaria
MOT of schistosomes
skin penetration
Most romantic parasite
schistosomes / blood flukes
(since they are always in copula or perpetual copulation)
describe adult female schistosomes
oviviparous (lay mature ova)
describe adult male schistosomes
have gynecophoral canal/grooves (where the female is held); larger than females
characteristic of the eggs of schistosomes
non-operculated (unlike other trematodes)
larval stages of schistosomes
MIRACIDIA —> SPOROCYST —> CERCARIA
no redia and metacercaria
habitat of adult schistosomes
blood vessels
parasite discovered in Mekong River
Schistosoma mekongi
Eggs resembles egg of S. japonicum, but smaller
Schistosoma mekongi
Adults of this parasite reside in small intestines venules
S. mekongi
Eggs resemble egg of S. haematobium, but with equatorial/central bulge
Schistosoma intercalatum
Adults of this parasite reside in colon venules (large intestine)
Schistosoma intercalatum
aka Oriental Blood Fluke
Schistosoma japonicum
Parasite common in Mindoro, Leyte, Sorsogon, Mindanao
Schistosoma japonicum
has the SMALLEST EGG among blood flukes
Schistosoma japonicum
LARGEST blood fluke in terms of size
Schistosoma japonicum
IH of Schistosoma japonicum
SNAILS:
Oncomelania hupensis quadrasi
Habitat of Schistosoma japonicum
BV: Superior mesenteric vein
Infective stage of Schistosoma japonicum
Cercaria (forked tailed larva)
a forked tailed larva
Cercaria
what happened to the cercaria (forked tailed larva) of schistosomes when they exhibit SKIN PENETRATION?
Tail is removed
Became a schistosomule/schistosomula/schistosomulum (tail less cercaria)
tail less cercaria
Schistosomule
Schistosomula
Schistosomulum
disease generally caused by schistosomes
Swimmer’s itch (aka Gulf-coast itch, Cercarial itch, Clam digger’s itch)
Dermatitis (allergic rxn) with pruritis at the site of cercarial skin penetration caused by schistosomes
Swimmer’s itch (aka Gulf-coast itch, Cercarial itch, Clam digger’s itch)
disease/conditions caused by Schistosoma japonicum
Snail Fever, Katayama disease, or Katayama fever
Hepatosplenic schistosomiasis
Oriental Schistosomiasis
Swamp fever
systemic hypersensitivity rxn to the schistosomulum migrating through tissue; caused by S. japonicum
Snail Fever,
Katayama disease, or
Katayama fever
most serious consequence of chronic schistosomiasis (caused by S. japonicum)
Hepatosplenic schistosomiasis
characterized of hepatomegaly, ascites (inc. peritoneal fluid), portal hypertension, and development of collateral circulation; enlarged tummy in children; caused by S. japonicum
Hepatosplenic schistosomiasis
Describe S. japonicum ADULT worm
Largest
With smooth integument
Describe S. japonicum EGG
Knob-like/curved hook of protuberance on one side (lateral knob)
Smallest egg of all schistosoma
With the largest adult among blood flukes and has a smooth integument
S. japonicum
aka Mansoni Blood Fluke
Schistosoma mansoni
Knob-like/curved hook of protuberance on one side (lateral knob); smallest egg of all schistosoma
S. japonicum
First reported by Theodore Bilharz
Schistosoma mansoni
Final host of Schistosoma mansoni
Man
Final host of S. japonicum
Man
IH of Schistosoma mansoni
SNAILS:
Biomphalaria spp.
Australorbis spp.
Tropicorbis spp.
Planorbis spp.
Habitat of Schistosoma mansoni
BV: Inferior mesenteric vein of the colon/rectum
Infective stage of S. mansoni
Cercaria
MOT of all schistosomes
Skin penetration
disease/condition caused by S. mansoni
Intestinal Bilharziasis
Describe S. mansoni ADULT worm
Smallest
With coarse tuberculation
Smallest ADULT fluke with coarse tuberculation
S. mansoni
Describe S. mansoni EGG
Light yellowish brown with large lateral spine on one side (rose-thorn appearance)
has a rose-thorn appearance of egg; light yellowish brown with large lateral spine on one side
S. mansoni egg
schistosomes with similar lab dx due to similarities in habitat
Schistosoma japonicum
Schistosoma mansoni
(both in mesenteric vein)
Lab dx for both Schistosoma japonicum and Schistosoma mansoni
Stool Examination
Rectal Biopsy – S. mansoni
Sedimentation techniques
Faust-Meleney’s Egg Hatching Technique (Miracidial hatching test)
Circumoval Precipitin Test (COPT)
Cercarial Hullen Reaction
Specific lab dx for S. mansoni
Rectal Biopsy
aka Miracidial hatching test
Faust-Meleney’s Egg Hatching Technique
procedure that uses a freshly collected stool or urine then dissolved in non-chlorinated water (presence of chlorine can destroy Schistosoma larva) placed in Erlenmeyer flask, covered, and stand overnight against light
Observed: Miracidia swimming at the upper layer of water (ova presence)
Faust-Meleney’s Egg Hatching Technique (Miracidial hatching test)
Definitive test for Schistosomiasis in PH
Circumoval Precipitin Test (COPT)
Circumoval Precipitin Test (COPT)
Spx: ?
Rgt: ?
(+): ?
Specimen: Serum
Reagent: Lyophilized eggs from rabbit
(+): Bleb formation microscopically
procedure that gives a positive rxn of cercaria shrinking after using a lyophilized cercaria in serum spx
Cercarial Hullen Reaction
Cercarial Hullen Reaction
Spx: ?
Rgt: ?
(+): ?
Specimen: Serum
Reagent: Lyophilized cercaria
(+): Shrinking of cercaria
aka Vesicular Blood Fluke
Schistosoma haematobium
parasite common in Nile River Valley
Schistosoma haematobium
Final host of Schistosoma haematobium
Man
IH of Schistosoma haematobium
SNAILS:
Bulinus spp.
Physopsis spp.
Biomphalaria spp.
Habitat of Schistosoma haematobium
BV: Vesical, prostatic, uterine venous plexuses of the urinary bladder
Infective stage of Schistosoma haematobium
Cercaria
Disease/condition caused by Schistosoma haematobium
Urinary Bilharziasis (Egyptian hematuria)
condition characterized by hematuria and shows a “sandy patches” in the lower urinary tract caused by S. haematobium
Urinary Bilharziasis (Egyptian hematuria)
Lab dx for Schistosoma haematobium
Urine Examination using a 24-hour UNPRESERVED urine
optimized recovery time of S. haematobium in urine
between NOON and 2 PM
Preferred spx for S. haematobium recovery
24-hour unpreserved urine (appearance of Schistosoma ova in urine is intermittent)
*preservation may destroy the ova
Describe Schistosoma haematobium ADULT worm
With fine tuberculation
Describe Schistosoma haematobium EGG
Large, prominent terminal spine
adult schistosome with fine tuberculation
Schistosoma haematobium
LARGE schistosome egg with prominent terminal spine
Schistosoma haematobium