C2. Common Cestode Infections Flashcards
What is the scientifically name for pig tapeworm?
Taenia solium
What is the scientifically name for beef Tapeworm?
Taenia saginata
Why are Taenia sodium and Taenia saginata flat?
They have no alimentary canal therefore they need to be flat to absorb nutrients
Who are the definitive hosts for t.saginata, t.solium and t.asiatica ?
Humans. Important for sexual reproduction where parasite matures into adulthood
Where do adult t.solium and T.saginata live ? How do they attach to this area?
They reside in the small intestine and attach via their scrolex
What is the main differences between the morphology of pig tapeworm and beef tapeworm?
Pig tapeworm contains a rostellum
Beef tapeworm does not contain a rostellum
What are proglottids?
Single segments on the tapeworm
True or false?
Proglottids behind the scolex are immature and become thicker as they mature
True
How can you tell that tapeworms are hermaphrodites?
Each mature proglottid has a female and male reproductive organs. Mature gravid proglottids are tased with faeces
What is infection with Taenia species called?
Taeniasis
Who is the intermediate host of Taenia species ?
Pigs and cows
Briefly describe the lifecycle of Taenia
- Cattle and pigs become infected by ingesting contaminated eggs or gravid proglottids
- Oncospheres hatch and penetrate the intestinal walls and circulate to muscle tissues
- Oncospheres develop into cysticerci in the muscle (infected stage)
- Humans infected by ingesting raw or uncooked meat
- T.solium or T.saginata attach on intestine wall with scolex
- Adults live in the small intestine
- Reproduction occurs. Eggs or gravid proglottides are passed in faeces
What symptoms are associated with taeniasis ?
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
What is it called when humans ingest gravid proglottides from Tania solium?
Cysticercosis, which isn more serious than taeniasis
Normally occurs in the pigs
What is unique about cysticercosis ?
Human is both the definitive and intermediate host
How are humans infected?
Ingesting food that contains the proglottids
or through auto infection- ingested though own faecal contamination or proglottids carried to stomach by reverse peristalsis (rare)
How is the brain, liver and other tissues of the human infected by cysticercosis ?
Onscospheres hatch and invade intestinal wall and migrate to striated tissue as well as the brain and liver
What are the symptoms of cysticercosis ?
If cystercosis found int he brain it fan cause serious problems like seizures or intracranial hypertension
What drugs are used to treat taeniasis and cystercercosis ?
Praziquantel (Drug of choice)
Niclosamide
Both unlicensed in the UK
How does PZQ work?
Flat worm loses ability to resist digestion and whole tapeworm rarely passed in faeces, degraded in the gut
How does Niclosamide work ?
Inhibits worms glucose uptake and oxidative phosphorylation, passed in faeces
Why isn’t niclosamide not the drug of choice ?
Although it is cheap and effective, it has numerous side effects
What does zoonotic infections mean?
When pathogens usually found in animals occasionally infects humans. I.e. Covid-19
Why are zoonotic infections important ?
- Animal reservoir more difficult to eradicate
- Pathology often more severe than human parasites
- Can be transmitted though pets or livestock
What disease is caused by Echinococcus granulosus?
Cystic echinococcosis
What disease is cause by Echinociccus multilocularis?
Alveolar eechinococcosis
What is the lifecycle of echinococcus?
- Adults reside in the small intestine of the host
- Gravid proglottides release eggs, which re passed in the faeces and are immediately infective
- Eggs are ingested by immediate host and eggs hatch in small intestine
- Oncosheres are release and penetrate intestinal wall
- This then migrate around the circulation usually to the liver or the lungs and develop hydatid cysts
- If animal is eaten with the infected organs the lifecycle can continue
How can humans become infected with echinococcosis ?
- Ingestion of eggs directly by intimate handling of pets
- Contaminated in soil or vegetable
- Contact with eggs when walking pets
What are the symptoms of cystic echinococcosis ?
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
What does the severity of the pathology of echinococcois depend on ?
Size, quantity and location of the cyst
What is the danger of a cyst bursting ?
Liberated protoscolices which may create secondary lists in other sites of the body.
can also case allergic reaction and death by anaphylactic shock
How would you diagnose echinococcosis?
- Ultrasound imaging
2. Serological Test
What drugs are used to treat echinoccocosis ?
Albendazole
Mebendazole
Praziquantel
Cystic echonococcosis- surgery or PAIR
Alveolar echinococcosis- surgery and long term Chemotherapy
