Cestoda

Question 1

what class and phylum is tapeworms part of

Answer 1

Phylum phlatyhelminthes

class cestoda

Question 2

Name the parts of the tapeworm

Answer 2

scolex- has rings of hooks and suckers to attach to host

neckpiece- where budding occurs for new proglottids (asexual)

stobila- body

segments of proglottids- immature near the neck and hermaphrodite near middle

Gravid proglottids- the eggs that released from faeces

Question 3

What type of fertilisation can tapeworms do and why

Answer 3

Can do cross fertilisation between proglottids; during copulation spermatozoa exchanged

self fertilisation as well bc they are HERMAPHRODITES

Opening called genital pore

Gravid proglottids form after mating

Question 4

Why do tapeworms not need digestive tract, mouth or anus

Answer 4

cestode enclosed in a TEGUMENT (protective covering)

Secretory and absorptive function with microvilli

Question 5

What other systems do cestodes have

Answer 5

excretory system: an excretory canal on each connected transverse canals; flame cells.

nervous system: a pair of cerebral ganglia in the scolex, lateral nerve cords along the strobila; a detached proglottid, has some movement and sensitivity.

Question 6

Where are the eggs fertilised in cestodes (and trematodes)

Answer 6

ootype (a bubble to
meet the gametes and yolk)

Question 7

What are the 2 larval stages (intermediate host)

Answer 7

Oncospheres

Cysticercus- when def host injests, scolex comes out and attaches to intestinal wall

Question 8

Why are human infections not as severe as larval infections

Answer 8

By ingestion of eggs or earlier larvae, larval stages form in intermediate host
Found in skin, liver, muscle, brain

Adult cestodes that cause human infection are not as severe

Question 9

Taenia saginata (beef tapeworm)

def, int, infective stages?

Answer 9

Definitive: humans

intermediate: catttle

Infective: adult tapeworm from cysticercus bovis

Question 10

Life cycle of taenia saginata

Answer 10

*eggs/gravid proglottids passed in faces

• cattle eat vegetation contaminated with proglottids

*Oncospheres hatch and penetrate intestinal wall and go to muscle (becomes cysticercus)

*Humans eat undercooked contaminated beef, cysticercus becomes tapeworm (scolex attatches in small intestine)

*Produces gravid proglottids that are passed through faeces

Question 11

Why is the cattle and pig more affected by the tapeworm than human

Answer 11

Parasite is in larval stages in intermediate host therefore more severe as it affects the muscle

Question 12

Taenia solium (pork tapeworm)

def, int, infective stages?

Answer 12

Def: Human

Int: Pig or human (due to similarity with pig protein)

Inf: cysticercus cellulosae

Question 13

Life cycle of Taenia solium

Answer 13

*proglottids shed with faeces and pig eat them

*Oncospheres hatch in the small intestine and form cysticercus in muscle

*Humans become infected after eating undercooked pork with cysticercus

*Adult proglottids removed with pills, larval stage found in brain/eye so harder to remove

Question 14

2 conditions caused by taenia solium that can occur in humans?

Answer 14

Taeniasis- intestinal infection with adult tapeworm due to eating undercooked contaiminated pork. NO major health implications

Cysticerosis- When food or water become contaminated with T.solium EGGS (can be from faeces of pig) Oncospheres can hatch and spread via blood to brain and eyes

Question 15

How to distinguish if its T. saginata or solium

Answer 15

Gravid proglottids:
< 12 (less than 12) uterine branches on proglottid=solium
>12 (more than 12) uterine branches =saginata

Scolex:
4 suckers no ring of hooks=saginata
4 suckers and 2 rows of hooks=solium

hosts:
human def host only=saginata
human can be int host as well with cysts in unusual places=solium

Question 16

compare the sizes of T.solium and T.saginata

Answer 16

solium: 2-3 metres

saginata: >4 metres

Question 17

Hymenolepis nana (dwarf tapeworm)

Answer 17

Def: human
Int: human (same host)/fleas
Infective stage: eggs
mode: ingesting the eggs from contaminated food

Question 18

H.nana Life Cycle

Answer 18

• eggs passed in poo +eaten by int host + develop cysticercoids
• humans get infected if int host eaten + develops in small intestine + produce gravid proglottoids.
• Eggs passed in poo
  *humans can get infected again if they ingest these eggs from their poo if hands hands not washed/ contaminated food and water.

Question 19

H. nana how can autoinfection occur?

Answer 19

happens if eggs remain in human intestine + release hexacanth embryo which penetrates intestine villus + cycle continues.

Question 20

how big is H.nana?

Answer 20

3-4 cm (most common in childeren)

Question 21

Echinococcus granulosus (dog tapeworm)

Answer 21

def: dogs/wolves
int: humans/herbivores
infective: eggs

Question 22

E.granulosus mode of infection in humans then dogs

Answer 22

human: ingesting eggs
dog:eating raw meat with cyst

Question 23

E.granulosus life cycle

Answer 23

• lives in dogs intestine +gravid pros release eggs + passed in poo
• humans can get infected after contact with dog +ingesting its egg
• eggs hatch in intestine + release oncospheres which migrate to diff organs
  *In organs they develop into hydatid cyst + can cause secondary cysts if rupture.

Question 24

E granulosus size

Answer 24

5-8mm

Question 25

how do dogs get reinfected? E granulosus

Answer 25

dogs get infected again if they eat herbivore like sheep with cysts

Question 26

Diphyllobothrium latum order?

Answer 26

Order Pseudophyllidea

Question 27

Diphyllobothrium latum (fish/broad tapeworm)

Answer 27

def: human/carnivores
1st int: cyclops
2nd int: fish
infective: plerocercoid

Question 28

Diphyllobothrium latum mode?

Answer 28

eating plerocercoid with infected undercooked fish

Question 29

D.Latum Life Cycle

Answer 29

*eggs passed in poo+ mature, hv oncospheres + develop into coracidia.
* Ingested by cyclops + coracidia turns to procercoid larvae
* larvae released from cyclops + eaten by 2nd host (small fish)
* migrates to deep tissue of fish + develop into plerocercoid larvae (infective stage for def host)

• humans might not eat the small fish but get the parasite after eating contaminated uncooked paratenic host fish.

Question 30

What is a hyatid cyst

Answer 30

a fluid filled cyst that contains the immature larval form of the parasite E.granulosus.

reside mostly in liver or lungs

Question 31

Why is cysticercus more severe than adult T.solium

Answer 31

occurs in intermediate host

found in harder places in body like brain, eye akin so harder to treat