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Class Trematoda
General characters
• Flat worms (no cavity),not segmented, bilaterally flattened (except Schistosoma is cylindrical)
• Hermaphrodite (except Schistosoma)
• Body has 2 suckers for attachment :oral, ventral,(except Heterophyes has a 3 rd genital sucker
General characters
• Life cycle show sexual phase (defenitive host) and asexual phase (intermediate host)
• Require one or more intermediate host• 1st intermediate host is a snail • Eggs have an operculum• Infective stage is encysted
metacercaria
(except schistosoma: cercariae)
Heterophyes heterophyes
• Heterophyes heterophyes adult
• Heterophyes heterophyes eggs: Heterophyes heterophyes snail
• Heterophyes heterophyes encysted metacercaria
• Heterophyes heterophyes in small intestine
snail: Pirenella conica Eggs: small, operculated, yellowish brown, thin shell (H.P)
•pear shaped,•very small size, (2mm) •oral,ventral, genital suckers•vitelline glands•2 testis, 1 ovary•simple intestinal ceaca • (L.P)
Heterophyes heterophyes adult in small intestine
Adult worm is present in intestinal villi
Heterophyes heterophyes encysted metacercaria in Bouri and Bolti muscles
Heterophyes heterophyes
• Location of adult: small intestine• Intermediate host: Primary: Pirenella conica Secondary: Bolti and Bouri fish• Infective stage: encysted metacercaria• Mode of transmission: ingestion of raw fish
containing encysted metacercaria• Diagnosis: eggs in stool• Disease: heterophiasis
Fasciola
• Fasciola hepatica adult
• Fasciola gigantica adult
• Fasciola gigantica snail: (lymnaea cailliaudi )
• Fasciola egg
OS: oral sucker
VS: ventral sucker
OV: ovary
TE: testis
Vi: vitelline glands
UT: uterus
INC: intestinal caeca
GP: genital pore
Fasciola hepatica Fasciola gigantica
cephalic cone, 2 shoulders, converging margins, simple medial branches of intestinal caeca,smaller in size
Less prominent shoulders, parallel margins, medial branches are T or Y shaped, larger in size
Snail (Lymnae caillaudi)
Fasciola egg:very large, operculated, yellow, thin shell
• Location of adult: bile duct• Intermediate host : primary : snail Lymnaea truncatula for
F.hepatica and Lymnaea. cailliaudi for F. gigantica secondary: leaves of fresh-water plants• Mode of transmission: ingestion of raw
water-cress containing encysted metacercariae
• Infective stage: encysted metacercaria• Diagnosis: eggs in stool• Disease: Fascioliasis
Schistosoma sp.
• Schistosoma mansoni male • Schistosoma mansoni female • Schistosoma mansoni male&female• Eggs of Schistosoma mansoni • Eggs of Schistosoma haematobium• Snail of Schistosoma mansoni• Snail of Schistosoma haematobium• S.mansoni cercaria
S. mansoni
S. mansoni male:8-10 mm, has gynacophoric canal, dorsal surface covered with tubercle
S. mansoni female:14 mm, taller and thinner,vitelline glands occupy 2/3 of the body
S.mansoni male&female
S. mansoni snail Biomphlaria alexandrina
Cercaria of S.mansoni: elongated head, biforked tail
S. mansoni egg:oval with lateral spine
S. Hematobium
Egg: oval with terminal spine Snail:Bulinus truncatus
S.mansoni S.hematobium
• Location:veins of large intestine, colon (lower mesentric vein
• Intermediate host:Biomphalaria alexandrina
• Diagnosis: eggs in stool• Infective stage: cercariae• Mode of transmission:direct
skin penetration of cercariae during swimming
• Disease: Intestinal Bilharziasis
• veins of urinary bladder (venous plexus of urinary bladder)
• Bulinus truncatus
• Eggs in urine• Cercariae• direct skin penetration of cercariae
during swimming
• Urinary Bilharziasis