C2. Common Cestode Infections

Question 1

What is the scientifically name for pig tapeworm?

Answer 1

Taenia solium

Question 2

What is the scientifically name for beef Tapeworm?

Answer 2

Taenia saginata

Question 3

Why are Taenia sodium and Taenia saginata flat?

Answer 3

They have no alimentary canal therefore they need to be flat to absorb nutrients

Question 4

Who are the definitive hosts for t.saginata, t.solium and t.asiatica ?

Answer 4

Humans. Important for sexual reproduction where parasite matures into adulthood

Question 5

Where do adult t.solium and T.saginata live ? How do they attach to this area?

Answer 5

They reside in the small intestine and attach via their scrolex

Question 6

What is the main differences between the morphology of pig tapeworm and beef tapeworm?

Answer 6

Pig tapeworm contains a rostellum

Beef tapeworm does not contain a rostellum

Question 7

What are proglottids?

Answer 7

Single segments on the tapeworm

Question 8

True or false?

Proglottids behind the scolex are immature and become thicker as they mature

Answer 8

True

Question 9

How can you tell that tapeworms are hermaphrodites?

Answer 9

Each mature proglottid has a female and male reproductive organs. Mature gravid proglottids are tased with faeces

Question 10

What is infection with Taenia species called?

Answer 10

Taeniasis

Question 11

Who is the intermediate host of Taenia species ?

Answer 11

Pigs and cows

Question 12

Briefly describe the lifecycle of Taenia

Answer 12

1. Cattle and pigs become infected by ingesting contaminated eggs or gravid proglottids
2. Oncospheres hatch and penetrate the intestinal walls and circulate to muscle tissues
3. Oncospheres develop into cysticerci in the muscle (infected stage)
4. Humans infected by ingesting raw or uncooked meat
5. T.solium or T.saginata attach on intestine wall with scolex
6. Adults live in the small intestine
7. Reproduction occurs. Eggs or gravid proglottides are passed in faeces

Question 13

What symptoms are associated with taeniasis ?

Answer 13

Few symptoms but you may not know that you have been infected

Non Specific symptoms:

• Obstruction, diarrhoea, hunger pains, weightless
• Appendicitis
• Discomfort and embarrassment as proglottides crawl from the anus

Question 14

What is it called when humans ingest gravid proglottides from Tania solium?

Answer 14

Cysticercosis, which isn more serious than taeniasis

Normally occurs in the pigs

Question 15

What is unique about cysticercosis ?

Answer 15

Human is both the definitive and intermediate host

Question 16

How are humans infected?

Answer 16

Ingesting food that contains the proglottids
or through auto infection- ingested though own faecal contamination or proglottids carried to stomach by reverse peristalsis (rare)

Question 17

How is the brain, liver and other tissues of the human infected by cysticercosis ?

Answer 17

Onscospheres hatch and invade intestinal wall and migrate to striated tissue as well as the brain and liver

Question 18

What are the symptoms of cysticercosis ?

Answer 18

If cystercosis found int he brain it fan cause serious problems like seizures or intracranial hypertension

Question 19

What drugs are used to treat taeniasis and cystercercosis ?

Answer 19

Praziquantel (Drug of choice)
Niclosamide
Both unlicensed in the UK

Question 20

How does PZQ work?

Answer 20

Flat worm loses ability to resist digestion and whole tapeworm rarely passed in faeces, degraded in the gut

Question 21

How does Niclosamide work ?

Answer 21

Inhibits worms glucose uptake and oxidative phosphorylation, passed in faeces

Question 22

Why isn’t niclosamide not the drug of choice ?

Answer 22

Although it is cheap and effective, it has numerous side effects

Question 23

What does zoonotic infections mean?

Answer 23

When pathogens usually found in animals occasionally infects humans. I.e. Covid-19

Question 24

Why are zoonotic infections important ?

Answer 24

1. Animal reservoir more difficult to eradicate
2. Pathology often more severe than human parasites
3. Can be transmitted though pets or livestock

Question 25

What disease is caused by Echinococcus granulosus?

Answer 25

Cystic echinococcosis

Question 26

What disease is cause by Echinociccus multilocularis?

Answer 26

Alveolar eechinococcosis

Question 27

What is the lifecycle of echinococcus?

Answer 27

1. Adults reside in the small intestine of the host
2. Gravid proglottides release eggs, which re passed in the faeces and are immediately infective
3. Eggs are ingested by immediate host and eggs hatch in small intestine
4. Oncosheres are release and penetrate intestinal wall
5. This then migrate around the circulation usually to the liver or the lungs and develop hydatid cysts
6. If animal is eaten with the infected organs the lifecycle can continue

Question 28

How can humans become infected with echinococcosis ?

Answer 28

1. Ingestion of eggs directly by intimate handling of pets
2. Contaminated in soil or vegetable
3. Contact with eggs when walking pets

Question 29

What are the symptoms of cystic echinococcosis ?

Answer 29

May be without symptoms

Cysts are slow growing, often found in the liver/lungs but also other organs including brain

Symptoms depends on size and site

Non-specific symptoms cough, abdominal pain or discomfort

Question 30

What does the severity of the pathology of echinococcois depend on ?

Answer 30

Size, quantity and location of the cyst

Question 31

What is the danger of a cyst bursting ?

Answer 31

Liberated protoscolices which may create secondary lists in other sites of the body.

can also case allergic reaction and death by anaphylactic shock

Question 32

How would you diagnose echinococcosis?

Answer 32

1. Ultrasound imaging

2. Serological Test

Question 33

What drugs are used to treat echinoccocosis ?

Answer 33

Albendazole
Mebendazole
Praziquantel

Cystic echonococcosis- surgery or PAIR
Alveolar echinococcosis- surgery and long term Chemotherapy