Cestoda (tapeworms)

Question 1

Why are tapeworms considered a mostly “perfect” parasite?

Answer 1

Literally have no digestive system, little nervous system. Live off of the host entirely

Question 2

What major challenge do cestodes face in their environment?

Answer 2

Staying in place despite Peristaltic movement of the gut.

Question 3

The outermost part of the female reproductive tract in the Cestodes is referred to as

Answer 3

Ovijector

Question 4

When a cestode proglottid is full of eggs it is referred to as ____

Answer 4

Gravid

Question 5

Cestodes range in size from ____ to ____

Answer 5

a few mm to several meters

Question 6

What is a “sparganum”? Do they always cause symptoms?

Answer 6

Migrating larvae of tapeworms that can infect many types of tissues, usually with a granuloma forming around them. They often develop without ever affecting the host, but may enter key areas such as the brain

Question 7

How can sparganosis be treated?

Answer 7

With praziquantel or surgery, but often use of praziquantel kills them, resulting in more inflammation which can be harmful if the sparganum is in the brain

Question 8

How does D. latum differ from most other tapeworms? What other defining traits do they have?

Answer 8

Have grooves rather than hooks or suckers, and the genital pores, testes, and vitellaria are in the center of the proglottid (medial). Their eggs are very definitive with a small bump near the operculum.

Question 9

What happens once a D. latum egg hatches?

Answer 9

Free swimming oncosphere or coracidium must reach water to complete development. Enters copepod and develops in the haemocoel as procercoid.

Question 10

What conditions do D. latum tapeworm infections cause?

Answer 10

Lack of vitamin B12 and anemia

Question 11

What is it called when a person has a genetic predisoposition to lack of vitamin B12

Answer 11

Avitaminosis

Question 12

Name/briefly describe the parts of the tapeworm head

Answer 12

Scolex - Head
Rostellum - Top of scolex, may be withdrawn
Hooks - for attaching to host (around rostellum)
Suckers - on every side of scolex

Question 13

Each section of a tapeworm is referred to as a ____

Answer 13

proglottid

Question 14

What types of structures may be present on a tapeworm scolex to aid in attachment?

Answer 14

Suckers, grooves, hooks, spines, tentacles, or combinations of those

Question 15

Where are new proglottids grown on the cestodes?

Answer 15

posterior end of scolex near strobila

Question 16

The parenchyma from one proglottid to the next is _____

Answer 16

continuous

Question 17

Why is the integumentary system of tapeworms so important? Is it divided in any way?

Answer 17

IT is important because it serves as the primary surface for nutrient intake. It is not divided into true segments but instead stretches across the whole organism.

Question 18

What type of muscle is found in tapeworms?

Answer 18

Circular

Question 19

If a tapeworm proglottid detaches when mature, it is referred to as ____. When it detaches when spent/senile it is referred to as ____ or _____. When it detaches while eggs are maturing it is referred to as ____.

Answer 19

Apolysis.
Anapolysis or pseudapolysis.
Hyperapolysis

Question 20

IF the posterior margin of one proglottid overlaps the anterior of the next, the tapeworm is referred to as _____

Answer 20

Craspedote

Question 21

The tapeworm larval stage in which the scolex is everted into a sac is referred to as ____

Answer 21

Cysticercus

Question 22

Briefly describe the basic features of the life cycle of a tapeworm

Answer 22

1. Egg hatches into a larval form called the oncosphere.
2. Oncosphere hatches either before or after ingestion by first host.
3. Larva becomes juvenil metacestode
4. Adult forms

Question 23

Which stage(s) in the tapeworm life cycle have many potential configurations based on genus/species? Describe stage(s)

Answer 23

Procercoid stage, which occurs in an arthropod intermediate host.
AND
Plerocercoid stage, which occurs after first intermediate host (arthropod) is consumed by second intermediate (usually a fish)

Question 24

_______ contains all the really important tape worms from the standpoint of human health

Answer 24

Taeniidae

Question 25

The causative agent of hydatid cysts is ____

Answer 25

Echinococcus granulosus

Question 26

What is the composition of hydatid cysts and how do they form?

Answer 26

Inner portion of the cyst is a part of the juvenile but the outer part is made from the host. The inner portion is separated from the outer host, preventing host immune response (which may send host into shock). Cysts are full of protoscolices (hundreds to thousands) that can cause infection if burst open (each one can form a new cyst)

Question 27

Describe the life cycle of Echinococcus spp.

Answer 27

1. Eggs are passed from definitive (canine) host in feces.
2. Eggs are ingested by an intermediate host (likely a warm blooded vertebrate).
3. Larva hatches in small intestine, penetrates lining and enters blood stream.
4. Larva usually enters liver, but can enter any organ
5. Larva develops into a hydatid cyst
6. Protoscolex attaches to host intestien and develops into tapeworm

Question 28

How large can hydatid cysts grow?

Answer 28

Golf ball size is common, basketball size is possible

Question 29

How are humans a dead end host for Echinococcus granulosus?

Answer 29

Dogs don’t often eat us, sooo…

Question 30

What is one of the problems with surgical hydatid cyst removal?

Answer 30

IF cyst bursts open, each tiny protoscolex can become a new cyst. Also, hydatid fluid may cause massive anaphylactic shock

Question 31

What are some of the general features of the tapeworm order Pseudophyllidea

Answer 31

1. Scolex has 2 longitudinal bothria
2. Genital pores medial or lateral
3. Vitellaria are folliculated and scattered throughout proglottid
4. Life cycles involve crustacean 1st intermediate hosts and fish second intermediate hosts

Question 32

The largest member of the order Pseudophyllidea is Hexagonoporus physeteris. How long is it and what is the host?

Answer 32

30m long, host is a sperm whale

Question 33

What is the most common human tapeworm infection?

How is it acquired? What is the first sign?

Answer 33

Diphyllobothrium. Acquired by eating raw/undercooked fish. The first sign is expelling proglottids from anus.

Question 34

What is “sparganosis”?

Answer 34

Caused when humans ingest tapeworm at the procercoid stage by drinking copepod infected water or eating undercooked infected second intermediate hosts (ex. mammals, reptiles, amphibians). The “spargana” (metacestode stage) can migrate anywhere in the body and begin growing to be up to 15 cm. Can go undiagnosed if it occurs in deep muscle, but many organs will have obvious symptoms. Can cause blindness in the eye.