PHYLUM PLATYHELMINTHES

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• PHYLUM PLATYHELMINTHES
• Class Cestoidea tapeworms
• -- all intestinal parasites of vertebrates
• -- no gut
• -- adults benign pathology due to larval stages
  

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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology
Scolex attachment organ
Neck region of strobilization
Strobila w/ proglottids
Mature proglottids
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 1. Scolex
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 1. Scolex
a. Nervous system
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 1. Scolex
b. Attachment devices 1) bothria
bothrium
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 1. Scolex
b. Attachment devices 2)
acetabulum
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 1. Scolex
b. Attachment devices 3) hooks and
rostellum
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 2. Neck
-- region of stobilization (asexual growth)
-- damaged by drug, Praziquantel
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 3. Strobila
and proglottids
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 3. Strobila
and proglottids mature proglottid
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 3. Strobila
and proglottids gravid proglottid
Gravid proglottid
Apolytic pass from host body
entire Anapolytic rupture inside host gut
eggs pass in feces
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms A. Morphology 4. Tegument
-- sunken epidermis -- microtriches
microthrix
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle larval
cestode metacestode
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 1.
Coracidium route a. egg ? coracidium
(free swimming) b. eaten by 1st IH ?
often a copepod
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 1.
Coracidium route c. penetates gut of
copepod becomes procercoid in coelom d.
copepod eaten by fish (2nd IH)
cercomere
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 1.
Coracidium route e. in fish host ?
plerocercoid f. fish eaten by DH
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route a. egg eaten by IH ?
oncosphere (hexacanth or decacanth) b.
penetrates gut ? metacestode
hexacanth oncosphere
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 1) cysticercoid larva
often in arthropod IH
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 2) cysticercus larva
bladder worm vertebrate IH
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 2) cysticercus larva
modifications -- strobilocercus
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 2) cysticercus larva
modifications -- coenurus (protoscoleces on
inner lining)
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 2) cysticercus larva
modifications -- unilocular hydatid cyst
(internal budding of cysts)
protoscolices
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms B. General Life Cycle 2.
Oncosphere route b. penetrates gut ?
metacestode 2) cysticercus larva
modifications -- multilocular (alveolar)
cyst (external budding)
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm -- subartic and temperate zones
-- most common human tapeworm -- largest
human tapeworm up to 25 m
with 4000 proglottids -- one infected human
can release 2- 40 million
eggs/day
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm
bothria
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm a. Life cycle -- adult in
small intestines of human anapolytic
? eggs in feces -- hatch into coracidium
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm a. Life cycle --
coracidium eaten by Diaptomus or Cyclops ?
procercoid
procercoid
Cyclops
Diaptomus
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm a. Life cycle -- copepod
eaten by planktivorous fish (perch) ?
plerocercoid
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm a. Life cycle --
planktivorous fish can be eaten by larger fish
-- fish IH eaten by human plerocercoid ?
adult cestode
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium latum broad fish
tapeworm b. Pathology 1) incidence
of infection -- 1 infected human can result
in 100,000 eggs/day entering water system,
even with proper sewage treatment 2)
adult worm typically causes few problems
3) in some hosts, causes tapeworm pernicious
anemia
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
2. Diphyllobothrium mansonoides -- causes
sparganosis in humans (zoonosis) a. Life
cycle -- DH cat egg out with feces ?
coracidium -- ingested by copepod ?
procercoid -- copepod eaten by frog,
reptile, small mammal (not fish) ?
plerocercoid ( sparganum) -- eaten by
cat
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms C. Order Pseudophyllidae
1. Diphyllobothrium mansonoides -- causes
sparganosis in humans (zoonosis) b.
Pathology 3 routes of transmission to
humans 1) accidental ingestion of infected
copepod ? plerocercoid 2) eating raw frogs,
snakes, pork ? paratenic host 3) using raw
flesh as poultice ? pleroceroid crawls into
tissue
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Sparganosis caused by pleroceroids of D.
mansonoides
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms D. Order Proteocephalata
1. Proteocephalus ambloplitis bass
tapeworm a. Life cycle
4. 2nd IH eaten by bass or pleroceroid in young
bass, reinvades gut ? adult
1. adults in gut apolytic eggs released in
water
2. Coracidium hatches eaten by Cyclops
? proceroid

• Cyclops eaten
• by planktivorous fish
• ? plerocercoid

2nd IH
1st IH
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms D. Order Proteocephalata
1. Proteocephalus ambloplitis bass
tapeworm b. Pathology parasite castration
pleroceroids
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
-- scolex with 4 acetabula w/ or w/o hooks
-- most medically important tapeworms --
follow the oncosphere route of development
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode a.
Taenia saginata beef tapeworm --
worldwide -- up to 75 ft. in length
scolex
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode a.
Taenia saginata 1) Life cycle --
DH humans in small intestines -- apolytic
proglottids active
Scolex no hooks
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode a.
Taenia saginata 1) Life cycle

• Adults in small
• intestines apolytic

• Human eats under-
• cooked beef

2. Eggs on grass eaten by cow (IH)

• Oncosphere released
• cysticercus in cows
• muscles

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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode a.
Taenia saginata 2) pathology
-- few problems (psychological effects of
mobile proglottids) -- humans rarely become
infected with the cysticercous larva --
incidence of cysticercus in beef measly
beef
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T. saginata measly beef
Killed by 56 oC (133 oF) freezing at -5 oC (23
oF) for at least 7 days
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode b.
Taenia solium pork tapeworm --
6-10 ft can reach 30 ft.
scolex
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode b.
Taenia solium 1) life cycle
-- DH human in small
intestines apolytic
Scolex w/ acetabula and hooks rostellum
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode b.
Taenia solium 1) life cycle
-- eggs released ingested by
pig -- oncosphere hatches, penetrates
gut ? cysticercus in tissues --
undercooked pork ingested by human
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• PHYLUM PLATYHELMINTHES
• III. Class Cestoidea tapeworms
• E. Order Cyclophyllidae
• 1. Species with cysticercus metacestode
• b. Taenia solium
• 2) pathology
• -- adults cause no problems
• -- metacestodes cause cysticercosis
  (Cysticercus cellulosae)
• routes of infection for cysticercosis
• ingest eggs
• gravid proglottids moved into stomach by
• reverse peristalsis
• ? massive release of oncospheres
• ? multiple cysticercous larvae in human host
• Cysticercus cellulosae
• (human DH and IH)

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Cysticercosis in human muscle
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Cysticercosis in eye and brain
cerebral cysticercosis
Ocular cysticercosis
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Tapeworm Diet Pills
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode c.
Taenia pisiformis DH canids
IH rabbits
Cysticercus larvae
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PHYLUM PLATYHELMINTHES III. Class Cestoidea
tapeworms E. Order Cyclophyllidae
1. Species with cysticercus metacestode d.
Taenia multiceps DH canids
IH herbivore (sheep) coenurus metacestode
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Gid (staggers) in sheep