Cestodes (Tapeworms)

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Questions and Answers

How many intermediate hosts does the Order Pseudophyllidea require?

2 (correct)

What is the main method of attachment for Cestodes in the Order Cyclophyllidea?

Rostellum

Bothria and scolex

Cilia

Suckers and scolex (correct)

Where are all adult Cyclophyllidea found within their final host?

Lungs

Stomach

Liver

Small intestines (correct)

What is the purpose of the larvae in the life cycle of Cyclophyllidea?

To develop into a scolex Signup and view all the answers

Which type of eggs have cilia for motility?

Pseudophyllidea eggs Signup and view all the answers

What is used by Pseudophyllidea for attachment to the host's organs?

Bothria and scolex Signup and view all the answers

What happens if humans ingest infected human feces but there is no intermediate host present?

Parasite gets lost and migrates to the brain, causing larval development. Signup and view all the answers

What feature is essential to note when trying to identify specific Cyclophyllidea species?

Size and shape of suckers Signup and view all the answers

In which host are the proglottids found in the life cycle of Cyclophyllidea?

(Dogs) final host Signup and view all the answers

Why is it crucial to obtain a complete picture of a parasite for identification purposes?

To determine the size of the parasite Signup and view all the answers

What is the number one preventable cause of epilepsy?

Taenia solium Signup and view all the answers

What is the primary method by which cestodes absorb nutrients?

Through their integument Signup and view all the answers

What type of life cycle do cestodes have?

Indirect Signup and view all the answers

Which feature is NOT important when trying to identify a cestode species?

Whether or not it has an alimentary canal Signup and view all the answers

In cestodes, where are male and female reproductive organs typically located?

In the proglottids Signup and view all the answers

'Pearly beef' may lead to financial loss for farmers due to what reason?

'Pearly beef' being inedible Signup and view all the answers

Which statement is true regarding larval stages in cestodes?

Only one type is present per species Signup and view all the answers

What clinical impact can heavy cestode infection have on young animals?

Clinical symptoms Signup and view all the answers

How many suckers can the cestode head (scolex) have?

4 Signup and view all the answers

What is the term used to describe the segments in a cestode's body?

Proglottids Signup and view all the answers

Which part of a cestode's body is most mature and developed?

Proglottids located furthest from the scolex Signup and view all the answers

What do cestodes lack due to their lack of a body cavity?

They lack intestines Signup and view all the answers

Which terminology is used refer to the body of the cestode?

Strobila Signup and view all the answers

What is the major goal of Cyclophyllidea tapeworm parasites?

To release proglottids into the environment Signup and view all the answers

In which host does Taenia solium's adult stage reside?

Humans Signup and view all the answers

What is the term for the opening on the scolex of the cestode?

Rostellum Signup and view all the answers

What is the primary reason dogs are dewormed for Cyclophyllidea tapeworms?

To address cosmetic concerns for the owner Signup and view all the answers

What is the term used to describe larva embedded in the muscle of cattle by Echinococcus species?

Pearly beef Signup and view all the answers

Which species serves as the intermediate host for Echinococcus tapeworms?

Cows Signup and view all the answers

What is the clinical sign of Taeniasis in a human host?

Itchy anus Signup and view all the answers

What is the role of oncospheres or hexacanth embryos in the life cycle of tapeworms?

Infecting intermediate hosts Signup and view all the answers

Where can larva of Taenia solium commonly be found within a pig?

In the tongue or any muscle of the pig. Signup and view all the answers

What is a possible consequence of larval infection with Taenia solium for humans?

Cysticercus formation in the brain. Signup and view all the answers

What is meant by 'pearly pork' in the context of the text?

Pork that contains larva embedded in the muscles. Signup and view all the answers

Where is Taenia solium commonly found according to the text?

South America and Africa Signup and view all the answers

What is NCC referred to?

Cysts formed in the brain. Signup and view all the answers

What can happen when humans ingest infected human feces containing the parasite Taenia solium?

The parasite gets lost and migrates to the brain, causing larval development and possibly leading to epilepsy. Signup and view all the answers

What is a key identifying factor when trying to identify cestode eggs?

Presence of "bony finger" structures Signup and view all the answers

Study Notes

Cestodes: General Info

Cestodes are in the phylum Platyhelminthes and are also known as "tapeworms".
They have a flat body and lack a body cavity (meaning that they lack intestines).
Their flat body has segments of proglottids.
They are hermaphroditic with both sex organs being present in each proglottid.

Cestodes: Body Structure

The cestode body includes the proglottids (segments), strobila (body), head, and neck.
The cestode head (AKA: scolex) has either 4 suckers or a bothria and can be armed or unarmed with hooks.
Most have a rostellum (mouth opening).
The cestode body (AKA: strobila) has proglottids (segments) and a mature posterior (portion of the body furthest from the scolex).

Order Pseudophyllidea

Has 2 intermediate hosts, with the first IH being a crustacean.
Uses BOTHRIA and scolex for attachment to the host's organs.
Their eggs are contained in oncospheres but have cilia for motility.

Order Cyclophyllidea

Has 1 intermediate host (IH).
Uses 4 suckers and scolex for attachment to the host's organs.
Their eggs are contained within an oncosphere.
All adult cyclophyllidea are ALWAYS found within the small intestines of their final host, regardless of the animal being used as the host.

Order Cyclophyllidea: Life Cycle

Step 1: The adult stage is found within the final host (dogs) where they use their rostellum to stay attached to the host's small intestines.
Step 2: The proglottids are found within the feces (from the final host) where eggs are released from the proglottid.
Step 3: The eggs are ingested by the IH (fleas) where the larvae will develop.
Step 4: The final host can ONLY be infected by CONSUMING the infected IH.

Order Cyclophyllidea: Identification

When trying to identify a cestode species, it is important to note:
- The size of the sucker
- Whether or not the sucker has hooks
- The shape of the sucker
- Whether or not a rostellum is present
- Whether or not the rostellum has hooks
The shape, width, and length of the proglottid
Whether or not fringe is present
If there are 1 or 2 genital pores
Where the glands are positioned

Clinical Relevance

Some can be zoonotic
Can cause clinical symptoms in young animals if the infection is heavy
If "pearly beef" is present, the meat has to be condemned, which can cause a financial loss for farmers
Larva invasion into the lungs or liver can cause illness in animals
Cestodes do not rely on seasonality for infection because their host defecates all year long, which is their mode of infection, through the feces

Cestodes: Taenia solium

Normal Life Cycle:
- Has a flattened shape and are hermaphroditic
- The adult stage is only found within the small intestines of the final host (humans)
- Clinical signs are rare within the final host
- The only clinical sign would be having an itchy anus (AKA: Taeniasis)
Abnormal Life Cycle:
- If humans ingest infected human feces, they can become infected with this parasite
- The parasite develops into cysticercus in the brain
- This can be extremely deadly and very commonly leads to epilepsy
- Taenia solium is the number one most preventable cause of epilepsy
- Humans act as an aberrant and dead-end host in this abnormal life cycle where the human is infected with the larval stage of this parasite
- Larval infection in the human brain is referred to as NCC (neurocysticercosis)

Hydatic cysts: Echinococcus species

When larva is found imbedded in the muscle of cattle, it is referred to as "pearly beef"
This species of tapeworm has humans as their final host, and cows as their intermediate host
The larva tend to imbed in the liver and lungs of the host

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Description

Learn about cestodes, also known as tapeworms, which are flatworms belonging to the phylum Platyhelminthes. Discover their flat body structure, segmented proglottids, and hermaphroditic nature with both sex organs present in each proglottid. Explore the anatomy of cestodes including the head (scolex) with suckers or hooks.