4. Mesozoa class
• Phylum Platyhelminthes
• Class Trematoda
• Subclass Digenea
• Subclass Aspidobothrea
• Class Turbellaria
• Class Monogenea
• Class Cestoidea
• Phylum Nematoda
• Class Chromadorea
• Superfamily Strongyloidea
• Superfamily Ascaridoidea
• Family Dracunculidae - Guinea worms
• Family Oxyuridae – Pinworms
• Family Onchocercidae – Filarial worms
• Class Enoplea
• Order Trichinellida
CLASSIFICATION IN OLDER LITERATURE
5. Helminth @ Parasitic Worms
Phylum Platyhelminthes Phylum Nematoda
Flatworm/ Cacing pipih Roundworm/ Cacing bulat
1. Class Trematode (fluke/ fluk)
a. Blood fluke
b. Intestinal fluke
c. Liver fluke
d. Lung fluke
2. Class Cestode (tapeworm/ cacing pita)
a. Fish tapeworm
b. Dog tapeworm
c. Fox tapeworm
d. Rat tapeworm
e. Pork tapeworm
f. Beef tapeworm
g. Dwarf tapeworm
h. Dog-Cat Flea tapeworm
1. Whip worm (cacing cambuk/
rambu)
2. Pork worm/ Trichina worm
3. Ascaris - Intestinal large
roundworm
4. Anisakis – Herring worm disease
5. Toxocara – domestic cat & dog
6. Threadworm/ cacing benang –
Strongyloides
7. Hookworm/ cacing cangkuk/ kait
8. Pinworm/ cacing kerawit
9. Filarial worm/ cacing filaria
8. • Flukes (Trematodes)
– Adult flukes are leaf-shaped flatworms. Prominent oral and
ventral suckers help maintain position in situ. Flukes are
hermaphroditic except for blood flukes, which are bisexual.
The life-cycle includes a snail intermediate host.
• Tapeworms (Cestodes)
– Adult tapeworms are elongated, segmented, hermaphroditic
flatworms that inhabit the intestinal lumen. Larval forms,
which are cystic or solid, inhabit extraintestinal tissues.
• Roundworms (Nematodes)
– Adult and larval roundworms are bisexual, cylindrical
worms. They inhabit intestinal and extraintestinal sites.
9. Phylum Platyhelminthes
• Or flatworms
• Dorsoventrally flattened
• Leaf shape or oval
• Bilaterally symmetrical
• Range in size (microscopic – 200 feet in length)
• Most are parasitic
11. Phylum Platyhelminthes
• Classification in older literature:
– Class Turbellaria
– Class Monogenea
– Class Trematoda (Digenea) – fluke
• Digeneans: Strigeiformes
– Family Diplostomidae – Alaria sp
– Family Strigeidae – Cotylurus sp
– Family Schistosomatidae – Schistosoma sp
• Digeneans: Echinostomatiformes
– Family Echinostomatidae – Echinostoma sp
– Family Fasciolidae – Fasciola sp
– Family Cathaemasiidae – Ribeiroria sp
– Family Paramphistomidae – Paramphistomum sp
– Family Diplodiscidae – Megalodiscus sp
• Digeneans: Plagiochiformes & Opisthorchiformes
– Family Dicrocoeliidae - Dicrocoelium sp
– Family Troglotrematidae – Paragonimus sp
– Family Heterophyidae – Heterophyes sp
– Family Opisthorchiidae – Clonorchis sinensis
– Class Cestoidea
12. 1. Class Turbellarians
• Most are free living
worms in terrestrial,
freshwater, and marine
environments.
• Some commensals or
parasites of
invertebrates,
especially of
echinoderms and
molluscs.
13. Class Turbellarians – cont…
TURBELLARIANS
Acoels Marine
Absence of an excretory system, pharynx and
permanent gut
Rhabditophorans Most symbiotic turbellarians
Temnocephalideans Small and flattened, with tentacles (anterior end ) and
a weak, adhesive sucker (posterior end).
Leechlike movement
Allocoels Irregular guts
Tricladids Large worms
Polycladids Complex gut with radiating branches
14. • Hermaphroditic
• Direct life cycle (one single host)
• External parasites of fish
– On gills and external surfaces (fins)
• Most are quite small but a few are large
– Marine forms > freshwater host
2. Class Monogenea
A
P
A
P
(Adhesive feeding organ)
with hooks
15. • All parasitic, mainly in digestive tract, of all classes of
vertebrates.
• Four subclass:
– Subclass Digenea
• Two host in life cycle (first (IH) always a mollusc)
– Subclass Aspidogastrea
• Most only one host (a mollusc)
– Subclass Didymozoidea
• Tissue-dwelling parasites of fish, no complete life cycle known,
but IH not required
– Subclass Cestoidea
• All parasitic, common in almost all classes of vertebrates, IH is
required for all species
3. Class Trematoda (Digenea)
16. • Blood fluke:
– Schistosoma mansoni, S. japonicum and S. hematobium
• Intestinal fluke:
– Fasciolopsis buski
• Liver fluke:
– Clonorchis sinensis, Fasciola hepatica
• Lung fluke:
– Paragonimus westermani
3. Class Trematoda (Digenea) – cont…
Tissue
flukes
18. Asexual reproduction
- Often occurs in larval or sexually immature stages as
either :
• polyembryony ( development of a single zygote into
more than one offspring/ many embryos) in flukes.
• Poly = >1 or many
• internal budding (new individual grows from
somatic tissue of its parent) in Echinococcus
granulosus.
a. Parasite Reproduction – cont.. (Lec 2)
22. 3. Class Trematoda (Digenea) – cont…
• Miracidium (larvae)
• cilia, slipper shape
• leaves the egg, swims looking for IH (snails)
• burrows into IH and loses the cilia
• turn to sporocyst or rediae
• Sporocyst
• number of embryos (sac of embryos) develop asexually to become rediae
• Rediae
• a larval form of a digenetic trematode (such as a liver fluke) that is produced within a sporocyst, has a
mouth, pharynx, and gut, and contains cells which give rise to other rediae or to cercariae
• Cercariae (additional embryos develop within rediae) – juvenile (larvae)
• a free-swimming larval stage in which a parasitic fluke passes from an intermediate host (typically a
snail) to another intermediate host or to the final vertebrate host.
• emerge from the snail to find next host and possess tail
• Metacercariae
• a tailless encysted late larvae of a digenetic trematode that is usually the form which is infective for the
definitive host
• curled up in a tissue cyst
• encysted metacercariae is infective to DH and develops into an adult trematode
25. The sporcyst develops internal chambers; and, within each chamber, a rediae develops
asexually. Each of the redia is also chambered and asexually produces a number of
internalized cercariae.
If a single miracidium is ingested by a snail, several hundred cercariae can be liberated.
