2. 2
Trematodes
General Characteristics
Leaf-like form unless Schistosomatidae, no
coelom
Motile organs: oral sucker (anterior
sucker) and ventral sucker
(acetabulum/posterior sucker)
Digestive system: begins at the mouth i/t
center of oral sucker pharynxesoph.
intestineblind end, no anus
Excretory system: excretory bladder
3. 3
Trematodes
General Characteristics
Genital system: hermaphroditic unless
Schistosomatidae
Operculated eggs, unless those of
Schistosomatidae
Require two intermediate hosts, unless
Schistosomatidae
4. 4
Trematodes
General Life Cycle
Eggs laid by adults appear outside w/ excretion
o/t final host
Eggs hatch in watermiracidiainvade or eaten
by 1st i’mediate host (snail)
Miracidia sporocysts rediae cercariae in
the body of snail (increasing in number)
Cercaria come out o/t snail, swim i/t water
invade the 2nd i’mediate host metacercariae
The final hosts are infected by metacercariae by
eating the 2nd i’mediate hosts adult
5. 5
Schistosomatidae
General Characteristics
Blood flukes
Requires 1
intermediate host
Egg has no operculum
Bifurcated tail cercaria
Sexually dimorphic,
male and female live
together
Anterior part contains
2 suckers
8. 8
Schistosoma japonicum
General
Distributed in Far East Asia e.g. Japan, China,
Thailand, Philippine, Malaysia and Indonesia
Causes schistosomiasis japonica, Katayama
disease
Sexually dimorphic
Habitat is superior mesenteric vein and branches
of final host
Final host is humans
Reservoir hosts are other mammals
Intermediate host is Ochomelania spp. snail
11. 11
Schistosoma japonicum
Morphology
Male:
About 15 mm long and broader than the
female, the body rolled ventrally to form
a groove, canalis gynecophorus, into
which the female worm fits
There are about 6-8 testes on the dorsal
side behind the ventral sucker
Smooth body surface
12. 12
Schistosoma japonicum
Life Cycle
Eggs in the feces o/t final host hatches i/t
watermiracidium
Miracidium invades the Onchomelania
sporocyst rediae cercaria
Cercaria comes out o/t snail and infects a final
host by adhering to the body surface w/ its
suckers and penetrating the skin
They move to the portal vein superior
mesenteric vein and develop into adults
15. 15
Schistosoma mansoni
General
Distributed in African continent, Middle East, and
South America
Causes intestinal bilharziasis
Sexually dimorphic
Habitat is inferior mesenteric vein and branches
of final host
Final host is humans
Reservoir hosts are other mammals
Intermediate host is Biomphalaria spp. snail
16. 16
Schistosoma mansoni
Morphology
Egg is large,
averaging 150x60
m without an
operculum, has
lateral spine, and
contains
miracidium
Bifucated tail
cercaria
17. 17
Schistosoma mansoni
Morphology
Female:
Slightly smaller than that of S.
japonicum, measuring 7-16 mm long
The ovary is located 1/3 the body length
from the anterior end
Covered w/ small spines on their
surface
18. 18
Schistosoma mansoni
Morphology
Male:
About 6-12 mm long and broader than
the female, canalis gynecophorus
There are about 8-9 testes on the dorsal
side behind the ventral sucker
There are many wart-like projections
on the body surface, many spines grow
on the warts
19. 19
Schistosoma mansoni
Life Cycle
The cycle is similar to that of S. japonicum
Intermediate host is Biomphalaria spp.
Cercariae invade the final host through
the skin, and grow to adults in various
veins of the portal system, especially
inferior mesenteric vein.
20. 20
Schistosoma haematobium
General
Distributed widely in African continent, especially
n the Nile Delta
Causes Egyptian hematuria, vesical or urinary
bilharziasis
Sexually dimorphic
Habitat is urinary vein and veins of pelvic cavity
Final host is humans
Reservoir hosts are other mammals
Intermediate host: various freshwater snails,
especially Bulinus spp
23. 23
Schistosoma haematobium
Morphology
Male:
About 10-15 mm long and broader than the
female, canalis gynecophorus
There are about 4-5 testes on the dorsal
side behind the ventral sucker
Covered by wart-like projections on the
body surface, no spines on the warts
24. 24
Schistosoma haematobium
Life Cycle
Similar to that of other Schistosomes, only
that the eggs appear in the urine o/t final
host
Intermediate host is especially Bulinus
snail
Cercariae invade the human skin, basically
follow the same way for the other species,
and settles in veins o/t pelvic cavity rather
than of the portal system
26. 26
Fasciola hepatica
General
Family Fasciolidae
Distributed entirely over Europe, southeastern
Africa, America continents, Oceania, and Japan
Final host: originally ruminants, occasionally
humans
Required 2 intermediate host; 1st is fresh water
snail (Lymnaea spp.), 2nd is water plants
27. 27
Fasciola hepatica
Characteristics
Adult: flat and leaf-like, 2-3 cm in length, 1 cm in
width, cephalic cone structure in the anterior
end
Complicated-branched intestine
Branched testis, branched ovary, coiled uterus
Vitelline gland has complicated branches,
spread all over the lateral body
32. 32
Fasciola gigantica
General
Family Fasciolidae
Distributed in Africa, southeast Asia,
Hawai, India, Pakistan
Life cycle resembles that of F. hepatica
33. 33
Fasciola gigantica
Characteristics
Adult: large, thin, and
long
Cephalic cone is not
very obvious
The internal structure
is similar to the
previous one
Egg is similar to other
Fasciolidae
35. 35
Clonorchis sinensis
General
Family Opistorchiidae
Distributed in Far East Asia
Clonorchis means branched testis
Final host: humans
Intermediate hosts: 1st is water snail
Bulinus and Parafossarulus manchouricus,
2nd is Cyprinidae fish
36. 36
Clonorchis sinensis
Characteristics
Adult: about 15x4 mm
Oral is slightly larger than ventral
sucker
Branched testis, lobulated ovary
Long, coiled uterus
Simple intestines
Vitelline gland is distributed in 1/3
center of the lateral body
40. 40
Opistorchis viverrini
General
First found in cat liver, nevertheless it
easily infects humans
Distibuted in Southern Asia, esp. in
Thailand
Intermediate hosts: 1st is water snail
Bythinia, 2nd is fresh water fishes
Life cycle is similar to previous species
41. 41
Opistorchis viverrini
Characteristics
Internal structure of adult resembles
that of C. sinensis, only for the shape of
testis and vitelline gland
Testes are lobulated, diagonally placed
Vitelline gland is also different
Egg is not easy to distinguish from that
of C. sinensis
