Cestodes

What are characteristics of Taenia species eggs?

3 pairs of hooklets hexacanth embryo radial striations on yellow brown embryophore 28-40 µm by 18-30 µm

What are the characteristics of Hymenolepis diminuta eggs?

3 pairs of hooklets hexacanth embryo polar thickening colorless embryophore 55 by 85 µm

What are the characteristics of Hymenolepis nana eggs?

3 paris of hooklets polar thickenings polar filaments colorless embryophore 45 by 38 µm

What does the scolex of Dipylidium caninum contain?

4 suckers club shapped rostellum 1-7 circlets of spines that reside on the rosetllum

What does the scolex of Hymenolepis diminuta contain?

4 suckers and a small rostellum with no hooks

Prevention and control measures against H. diminuta include all except which of the following? A. Vaccination program B. Effective rodent control C. Inspection of food prior to consumption D. Protection of food from rodents

A

The characteristic of the life cycle of H. nana that differentiates it from the other cestodes is which of the following? A. Lack of an intermediate host. B. Infective larval stage. C. Need for external environment D. Larval passage through the lungs

A

The egg of D. latum is unique among the cestodes in that it contains which of the following? A. An operculum and terminal knob B. Radial striations and oncosphere C. An operculum and lateral spine D. A ciliated rhabditiform larva

A

Which is the preferred drug for treating intestinal infection by Taenia spp.? A. Praziquantel B. Penicillin C. Nicolasamide D. Pentamidine

A

Prevention and control measures to prevent D. caninum infection include all except which of the following? A. Treat dog and cat pets to prevent fleas. B. Warn children against dog and cat licks. C. Deworm dog and cat pets, as needed. D. Neuter dog and cat pets.

D

Which of the following is characteristic of an H. diminuta egg? A. Spherical, with radial striations B. Ellipsoid, with terminal polar plugs C. Oval, with thin shell and polar filaments D. Oval, with polar thickenings and no filaments

D

Which of the following is not a usual site for Echinococcus granulosus infection in humans? A. Brain B. Liver C. Lung D. Genitalia

D

Sparaganosis

Develops from a procercoid larva

A 55-year-old man and his family had returned to the United States after a visit to his native Finland. While there, he enjoyed fishing and cooking the fish over an open fire. After his return, he visited his physician with complaints of diarrhea, abdominal pain, and some cramping. Bacterial culture of a stool specimen was negative for enteric pathogens. However, the microscopic O&P examination revealed several large, oval, operculated eggs. With this brief history, which tapeworm is suspected?

Diphyllobothrium latum

Specify the infective stage name for each of the cestodes A. Taenia saginata B. Dipylidium caninum C. Hymenolepis nana D. Diphyllobothrium latum E. Taenia solium F. Echinococcus granulosus G. Hymenolepis diminuta

A. Cysticercus. B. Cysticercoid larva (in flea). C. Egg. D. Plerocercoid. E. Cysticercus. F. Egg. G. Cysticercoid larva (in beetle or flea)

Zoonotic

Acquired from animals

A persistent cough, localized pain, and liver and lung involvement are associated with an infection with which of the following cestodes? A. Diphyllobothrium latum B. Echinococcus granulosus C. Both A and B D. Neither A nor B

B

A unique characteristic of Dipylidium caninum is which of the following? A. Lack of suckers on the scolex B. Formation of egg packets C. Proglottid resemblance to Taenia solium D. Alternation of female and male proglottids

B

The cestode morphologic form characterized by a segmented appearance that houses male and female reproductive structures is referred to as a(an): A. Scolex B. Proglottid C. Egg D. Cyst

B

The infective stage of H. diminuta for humans is which of the following? A. Rhabditiform larva B. Cysticeroid larva C. Embryonated egg D. Encysted form

B

The primary means of developing an intestinal infection with Taenia spp. is via which of the following? A. Skin penetration of larvae B. Ingestion of raw or poorly cooked meat C. Egg consumption D. Drinking contaminated water

B

Which of the following associations is correct for D. latum? A. Snail-coracidium B. Copepod-procercoid C. Fish-cysticercus D. Beetle-pleurocercoid

B

Which of the following does not apply to H. nana? A. Dwarf tapeworm B. Steatorrhea C. Proper hygiene and sanitation procedures D. Praziquantel therapy

B

Which of the following procedures would not be appropriate for diagnosing an infection with Echinococcus granulosus? A. Serologic procedure, such as ELISA B. O&P examination of stool specimen C. CT scan of suspect organ D. Biopsy of cyst

B

A 2-year-old girl and her pet dog were diagnosed with D. caninum infection. This infection was acquired by which of the following? A. Ingestion of the parasite's egg B. Penetration of soil larva C. Ingestion of a flea D. Consumption of poorly cooked beef

C

A primary differential feature between an H. nana egg and H. diminuta egg is which of the following? A. A flattened side for H. diminuta egg B. A thick shell for H. nana egg C. Polar filaments in H. nana egg D. Radial striations in H. diminuta egg

C

Characteristics of the cestodes include all the following except: A. They are hermaphroditic. B. They generally require intermediate host(s). C. Their laboratory diagnosis consists of finding larvae in feces. D. Their anatomic regions include the scolex, neck, and strobila.

C

In humans, Echinococcus granulosus infection results in which of the following? A. Eggs similar to those of H. nana B. A nutritional deficiency C. A hydatid cyst D. Filariform larva

C

The primary pathology associated with a D. latum infection is which of the following? A. Eosinophilic pneumonitis B. Vitamin D deficiency C. Vitamin B12 deficiency D. Fat malabsorption

C

Which of the following are key distinguishing factors in differentiating an infection between T. saginata and T. solium? A. Egg morphology and number of uterine branches in proglottid B. Presence of hooklets on scolex and egg morphology C. Presence of hooklets and number of uterine branches in proglottid D. Egg morphology and presence of suckers on scolex

C

Hermaphroditic

Contains both male and female organs

Coracidium

Free-swimming larva of D. latum

Oncosphere

Hexacanth embryo

What are symptoms of Diphyllobothrium latum?

Intestinal obstruction and vitamin B12-induced macrocytic anemia may develop

Cysticerus

Larval form of Taenia spp.

Proglottids

One of the segments of a tapeworm, containing both male and female reproductive organs

Proglottid

Segment of a tapeworm

Strobila

Series of proglottids

Brood capsule

Smaller cyst within a hydatid cyst

A 30-year-old recent immigrant from Mexico, living in Colorado, presented to the Hispanic Health Clinic after experiencing a seizure at his worksite His history revealed numerous headaches for several weeks. The basic neurologic examination was normal; however, fearing a malignancy, the physician ordered a CT scan. Calcified lesions were noted. A biopsy revealed a parasitic infection. What organism is suspected?

Taenia solium

Taenia saginata

beef tapeworm

Diphyllobothrium latum

broad fish tapeworm

dipylidium canninum

dog/cat, pumpkin seed tapeworm

Hymenolepis nana

dwarf tapeworm

What are the characteristics of mature and gravid Dipylidium caninum proglottids?

each mature segment contains two sets of both male and female reproductive organs Full of eggs in enclosed embryonic membrane resmble pumpkin seeds

Referring to the prolottid of T. saginata and T. solium, what is the difference between the two?

former has a longer and wide shape compared to the latter with a more square look former has 15-30 lateral branches on each side of uterus while latter has 7-15

In what parts of the world is Diphyllobothrium latum endemic?

great lakes, SA, AS, Central Africa, Baltic Region, Finland

Scolex

head of tapeworm

What is the larval stage of E granulosus?

hydatid cysts

Echinococcus granulosus

hydatid tapeworm / dog tapeworm

What does the scolex of Diphyllobothrium latum contain?

it is an almond shape with 2 long sucking grooves

What is a difference between adult T. saginata and T. solium?

latter has a rostellum with hooklets.

What are the characteristics of Diphyllobothrium latum eggs?

non hexacanth embryo coracidium (undeveloped embryo) lid structure on one end (operculum) terminal knob on one end (abopercular knob) smooth yellow-brown shell 55-75 µm long, 40-55 µm wide

What are clinical signs of intestinal cestode infection?

nondescript gastrointestinal discomfort, including diarrhea and abdominal pain which may devlop into nausea, dizziness, headache, and weight loss.

what phylum do cestoda belong to?

platyhelminthes

Taenia solium

pork tapeworm

Suckers

provide a worm to attach to the intestinal mucosa of the infected host

Hymenolepis diminuta

rat tapeworm

What does the scolex of Hymenolepis nana contain?

short rostellum with hooks

What are the characteristics of Dipylidium caninum eggs?

six hooked onconosphere egg packet containing 5-30 eggs 30-60 µm diameter for each egg

What is the adult of Echinococcus granulosus look like?

small (4.5mm) scolex has 36 hooks and 4 suckers 3 proglottids

Scolex

the anterior end of a tapeworm, bearing suckers and hooks for attachment.

What are the characteristics of Echinococcus granulosus eggs?

they are indistinguishable from eggs of Taenia spp. diagnostic stage is the larval stage

What are the characteristics of mature and gravid Diphyllobothrium latum proglottids?

wide and long centrally located rosette shaped uterine structure