Mod3: Cestodes (Tapeworms)

Front 1

Name the 5 types of diseases caused by cestodes (tapeworms)

Back 1

a. Taeniasis
b. Ciphyllobothriasis
c. Cysticercosis
d. Hydatid cyst Disease
e. Hymenolepiasis

Front 2

describe the classification of cestodes beginning with parasites

Back 2

Parasites -> metazoa (helminths) -> platyhelminthes (flatworms) -> cestoda (tapeworms)

Front 3

Taenia Solium
Primary or definitive hosts
secondary or intermdiate host
mode of transmission

Back 3

i. Primary or definitive hosts: humans
ii. Secondary or intermediate host(s): pigs
iii. Mode of Transmission:
1) Ingest larvae in undercooked pork
2. Ingest eggs in food or water contaminated with human feces

Front 4

Taenia Saginata
Primary or definitive hosts
secondary or intermdiate host
mode of transmission

Back 4

i. Primary or definitive hosts: humans
ii. Secondary or intermediate host(s): cattle
iii. Mode of Transmission: Ingest larvae in undercooked beef

Front 5

Diphyllobothrium Latum
Primary or definitive hosts
secondary or intermdiate host
mode of transmission

Back 5

i. Primary or definitive hosts: humans
ii. Secondary or intermediate host(s): copepods and fish
iii. Mode of Transmission: Ingest larvae in undercooked fish

Front 6

Echinococcus granulosus
Primary or definitive hosts
secondary or intermdiate host
mode of transmission

Back 6

i. Primary or definitive hosts: dogs
ii. Secondary or intermediate host(s): sheep
iii. Mode of Transmission: Ingest eggs in food or water contaminated with dog feces

Front 7

Taenia Solium
Main sites affected in human body
Diagnosis
Treatment

Back 7

iv. Main sites affected in human body:
1) Intestine
2) Brain and eyes (cysticerci)
v. Diagnosis: proglottids in stool
vi. Treatment: Praziquantel

Front 8

Taenia Saginata
Main sites affected in human body
Diagnosis
Treatment

Back 8

iv. Main sites affected in human body: Intestine
v. Diagnosis: Proglottids in stool
vi. Treatment: praziquantel

Front 9

Diphyllobothrium latum
Main sites affected in human body
Diagnosis
Treatment

Back 9

iv. Main sites affected in human body: Intestine
v. Diagnosis: operculated eggs in stool
vi. Treatment: praziquantel

Front 10

Echinococcus granulosus
Main sites affected in human body
Diagnosis
Treatment

Back 10

iv. Main sites affected in human body: Liver, lungs and brain (hydatid cysts)
v. Diagnosis: biopsy, CT scan, serology
vi. Treatment: albendazole or surgical removal

Front 11

Taeniasis Causes (3)

Back 11

i. Caused by 3 species:
i. T. saginata
ii. T. solium
iii. T. asiatica

Front 12

Taeniasis Life Cycle (6)

Back 12

1. Humans are the only hosts for these Taenia tapeworms
2. Humans pass tapeworm segments and/or eggs in feces and contaminate the soil in areas where sanitation is poor
3. Cows and pigs become infected after feeding in areas that are contaminated with taenia eggs from human feces
4. Once insdie the cow or pig, the Taenia eggs hatch in the anima's intestine and migrate to straited muscles to develop into cysticerci, causing a disease known as cysticercosis
5. Humans eat raw or undercooked beef or pork containing infective cysticerci
6. The cysticerci then migrate to the small intestine and mature to adult tapeworms

Front 13

Taeniasis Pathophysiology (5)

Back 13

1. Most people have no symptoms or mild symptoms
2. Patients with T. saginata often experience more symptoms, because T. saginata is larger (up to 10 meters) than T. solium
3. Tapeworms can cause digestive problems including abdominal pain, loss of appetite, weight loss, and upset stomach
4. The most visible symptom is the active passing of proglottids (tapeworm segments)
5. Tapeworm segments rarely become lodged in the appendix or the bile and pancreatic ducts

Front 14

Taeniasis Dx, Rx, & Prevention

Back 14

i. Diagnosis: patient may report passing proglottids in stool or they may be found on stool examination
1. Eggs are found less often than the proglottids
2. Treatment: praziquantel (drug used for virutally every flatworm)
3. Prevention: cook beef and pork adequately and dispose of human waste probperly so that cattle and swine cannot consume human feces

Front 15

T. solium v. T. saginata (3)

Back 15

1. *Patients can tell you what it was based on appearance
2. T. solium: has suckers and hooks!
3. T. saginata: NO hooks!

Front 16

Diphyllobothriasis Life cycle
infective stage (4)
Diagnostic stage (1)

Back 16

1. Infective Stage:
a. Infected crustacean ingested by small freshwater fish
b. Proceroid larva released from crustacean
c. Develops into plerocercoid larva
d. -predator fish eats infected small fish and human eats this fish raw or undercooked
2. Diagnostic Phase: Unembryonated eggs passed in human feces

Front 17

Diphyllobothriasis Pathogenesis (3)
1, caused by what?
2. causes damage to what organ?
3. epidemiology

Back 17

1. Caused by Diphyllobothrium lactum
a. Largest human parasite: up to 50 ft with 3000-4000 proglottids
b. Scolex lacks typical suckers and hooks; has sucking grooves
2. Infection causes little damage in small intestine
a. Megaloblastic anemia may occur as a result of vitamin B12 deficiency caused by preferential uptake of the vitamin by the worm
3 Epidemiology:
a. Related to ingestion of raw or inadequately cooked fish ad contamination of bodies of fresh water with human feces
b. Found worlwide but endemic in areas where eating raw fish is the custom, such as Scandinavia, northern Russia, Japan, Canada and certain north-central states in the US

Front 18

Diphyllobothriasis Presentation, Dx, Rx, & Prevention

Back 18

i. Most patients are asymptomatic, but abdominal discomfort and diarrhea can occur
a. Megaloblastic anemia due to B12 deficiency
ii. Laboratory Diagnosis: identification of typical oval, yellow-brown eggs with an operculum at one end in stools
a. There is no serological tests
iii. Treatment: praziquantel
iv. Prevention: adequately cook fish and properly dispose of human feces

Front 19

Human Cysticercosis
1. caused by what?
2. where can it be found in the human body?
3. presentation?

Back 19

1. Human cysticercosis is caused by T. solium larvae
2. Cysticerci can become large, especially in the brain, where they manifest as space-occupying lesion
a. Living cysticerci do not cause inflammation, but when they die they can release substances that provoke an inflammatory response
b. Eventually, cysticerci calcify
3. Cysticercosis causes headache, vomiting and seizures when the larvae are in the brain
a. Subcutaneous nodules containing larvae also occur commonly
b. Cysticercosis in the eyes can appear as uveitis or retinitis, or the larvae can be visualized floating in the vitreous

Front 20

Human Cysticercosis: life cycle (5)

Back 20

1. Proglottids (bundles of tapeworm eggs) pass into the environment via feces
2. Pigs and humans acquire parasites by eating food and water contaminated by eggs or by autoinfection
3. Cysticerci develop in pig muscle tissue
a. Cysticerci can lodge in human tissues such as brain, eyes and skeletal muscle
4. Humans acquire adult tapeworm infection by ingesting raw or undercooked meat with cysticerci
5. Proglottids pass into the environment via feces ….

Front 21

Human Cysticercosis: Dx, Rx, & Prevention

Back 21

i. Diagnosis depends on demonstrating the presence of the cyst in tissue, usually by surgical removal or computed tomography (CT) scan
a. Serologic test, e.g., ELISA, that detect antibodies to T. solium antigens are available, but may be negative in neurocysticercosis
ii. Treatment is either praziquantel or albendazole, but surgical excision may by necessary
iii. Prevention: treat patients to prevent autoinfection and observe proper hygiene, including hand washing, to prevent contamination of food with the eggs

Front 22

Unilocular Hydatid Cyst Disease (4)
1. caused by what?
2. found in what areas of world?
3. forms what in the body?
4. what do the cysts act like?

Back 22

a. Caused by Echinococcus granulosus, the dog tapeworm
b. Found primarily in shepherds living in the Mediterranean region, the Middle East and Australia
i. Most US cases reported from western states
c. Usually forms one large fluid-filled cyst containing thousands of individual scoleces as well as many daughter cysts
i. Hydatid Sand: Individual scoleces lying at the bottom of the large cyst
d. Cyst acts as a space-occupying lesion
i. Outer layer of cyst is thick, fibrous tissue produced by the host

Front 23

Unilocular Hydatid Cyst Disease: Life Cycle
Infectious Stage:
Diagnostic Stage:

Back 23

i. Infectious Stage : embryonated egg in feces
ii. Diagnostic Stage: Hydatid cyst in liver, lungs …

Front 24

Unilocular Hydatid Cyst Disease: Presentation

Back 24

f. Frequently Asymptomatic
i. Liver cysts may cause hepatic dysfunction
ii. Lung cysts can erode a bronchus, causing bloody sputum
iii.Cerebral cysts can cause h/a and focal neurologic signs

Front 25

Unilocular Hydatid Cyst Disease
cysts fluid contains what?
what happens if the cysts bursts?

Back 25

1. Cyst fluid contains parasite antigens
2. If the cyst ruptures spontaneously or during trauma or surgical removal, life-threatening anaphylaxis can occur
a. Rupture of a cyst can also spread protoscoleces widely

Front 26

Unilocular Hydatid Cyst Disease: Dx, Rx & Prevention

Back 26

i. Lab Dx: Mx examination revealing brood capsules containing mutliple protoscoleces
1. Serologic tests are available
2. Treatment involves albendazole withor without surgical removal of the cyst
a. Extreme care must be exercised to prevent release of the protoscoleces during surgery
b. A protoscolicidal agent, e.g., hypertonic saline, should e injected into the cyst to kill the organisms and prevent accidental dissemination
iii.Prevention of human disease involves not feeding the entrails of slaughtered sheep to dogs

Front 27

Hymenolepiasis
caused by what?
can be confused by what?
how is this different from tapeworms?

Back 27

a. Caused by Hymenoleis nana, the "dwarf" tapeworm
b. Only 15-40 mm long and can be confused with pinworms
c. Unlike other tapeworms, eggs are directly infectious for humans and can develop into adult worms without an intermediate host

Front 28

Hymenolepiasis: where do eggs hatch?

Back 28

1. Eggs hatch in duodenum, differentiate into cysticercoid larvae and then adult worms
i. Gravid proglottids detach, disintegrate and release fertilized eggs that pass in the stool or re-infect the small intestine: autoinfection

Front 29

Hymenolepiasis: how do patients present?

Back 29

1. Causes little damage; most patients are asymptomatic
2. Unlike other tapeworms, where only one adult worm is present, many worms (sometimes hundreds) are found

Front 30

Hymenolepiasis:
1. distribution?
2. diagnosis
3. treatment
4. prevention

Back 30

1. Worldwide distribution; common in tropics
a. In US, most common in southeast and in children
2. Diagnosis is based on finding eggs in stools
3. Treatment: praziquantel
4. Prevention consists of good personal hygiene and avoidance of fecal contamination of food and water