Question 1

If a U.S. citizen never leaves the United States, which of the following is the only disease that he or she could acquire?
A) Clonorchis sinensis
B) Fasciolopsis buski
C) Fasciola hepatica
D) Paragonimus westermani

Accepted Answer

Fasciola hepatica is found worldwide in sheep-raising areas. All the other parasites are found in the Far East. P. westermani is also found in India and parts of Africa.

Question 2

The egg of one trematode species can be recovered in urine. This parasite is:
A) Clonorchis sinensis
B) Heterophyes heterophyes
C) Schistosoma haematobium
D) Schistosoma japonicum

Accepted Answer

S. haematobium adults live in blood vessels near the bladder and rectum. Eggs shed in tissue may eventually appear in the bladder and then appear in the urine.

Question 3

For which of the following is sputum useful in the diagnosis of parasitic infection?
A) Clonorchis sinensis
B) Fasciola hepatica
C) Paragonimus westermani
D) Schistosoma mansoni

Accepted Answer

The P. westermani larva exits the cyst and migrates to the lungs, where it matures to become an adult.

Question 4

Two helminth eggs resembling each other are:
A) Ascaris lumbricoides and Trichostrongylus spp.
B) Diphyllobothrium latum and Paragonimus westermani
C) Fasciola buski and Opisthorchis sinensis
D) Hymenolepis nana and Taenia solium

Accepted Answer

D. latum and P. westermani are both operculated and both have terminal knobs or thickenings.

Question 5

The infective form in the Fasciola hepatica life cycle is the:
A) Redia
B) Metacercaria
C) Cercaria
D) Sporocyst

Accepted Answer

Metacercariae encyst on plants, crayfish, or fish, which are ingested by susceptible hosts.

Question 6

Two trematode eggs that resemble each other are:
A) Fasciola hepatica and Fasciolepsis buski
B) Schistosoma japonicum and Heterophyes heterophyes
C) Paragonimus westermani and Clonorchis sinensis
D) Schistosoma haematobium and Schistosoma mansoni

Accepted Answer

Fasciola hepatica and Fasciolopsis buski eggs cannot be differentiated visually, so species differentiation relies on symptoms, travel history, and recovery of an adult organism.

Question 7

All of the following Digenea infections are acquired by ingesting dormant larval forms EXCEPT:
A) Clonorchis sinensis
B) Heterophyes heterophyes
C) Paragonimus westermani
D) Schistosoma haematobium

Accepted Answer

Schistosoma haematobium infection occurs when cercariae penetrate broken skin, lose their tails, and migrate to blood vessels around the bladder.

Question 8

A large egg (180 µm x 80 µm) with a pointed lateral spine was recovered in feces from an immigrant of the West Indies. A likely parasitic infection would be:
A) Clonorchis sinensis
B) Fasciola hepatica
C) Schistosoma japonicum
D) Schistosoma mansoni

Accepted Answer

Eggs of Schistosoma spp. are not operculated as are the other Digenea parasites. Also, the distinctive lateral spine further confirms the identification.

Question 9

The immature schistosome found in human tissue is called the:
A) Cercaria
B) Miracidium
C) Redia
D) Schistosomule

Accepted Answer

Cercariae penetrate skin and then lose their tails to become a schistosomule before moving through the blood vessel to the final maturation site.

Question 10

An Asian patient with intestinal obstruction, mucoid diarrhea, and eosinophilia was tested for fecal parasites. The fecal sediment revealed a large (180 µm x 90 µm) oval egg with a small operculum. This parasite probably is:
A) Clonorchis sinensis
B) Fasciolopsis buski
C) Fasciola hepatica
D) Paragonimus westermani

Accepted Answer

Travel history or country of origin and clinical symptoms are important when differentiating trematode species, especially F. buski and F. hepatica. F. buski is found in Asia and invades the patient's GI tract, causing intestinal tract disease; F. hepatica (found worldwide) invades the liver, causing hepatic symptoms.

Question 11

Name the parasite shown in the following image: 
A) Clonorchis sinensis
B) Diphyllobothrium latum
C) Fasciola hepatica
D) Paragonimus westermani

Accepted Answer

This view is of the egg of Fasciola hepatica. This large egg is not easily differentiated from that of Fasciolopsis buski. The final determination relies on geographic distribution, travel history, or recovery of the adult.

Question 12

Name the parasite shown in the following image: 
A) Clonorchis sinensis
B) Schistosoma haematobium
C) Schistosoma japonicum
D) Schistosoma mansoni

Accepted Answer

This view is of the egg of Schistosoma haematobium. The differentiating characteristic is the presence of the terminal spine visible in the lower right position in this image.

Quiz 3: Digenea

If a U.S. citizen never leaves the United States, which of the following is the only disease that he or she could acquire?

The egg of one trematode species can be recovered in urine. This parasite is:

For which of the following is sputum useful in the diagnosis of parasitic infection?

Two helminth eggs resembling each other are:

The infective form in the Fasciola hepatica life cycle is the:

Two trematode eggs that resemble each other are:

All of the following Digenea infections are acquired by ingesting dormant larval forms EXCEPT:

A large egg (180 µm x 80 µm) with a pointed lateral spine was recovered in feces from an immigrant of the West Indies. A likely parasitic infection would be:

The immature schistosome found in human tissue is called the:

An Asian patient with intestinal obstruction, mucoid diarrhea, and eosinophilia was tested for fecal parasites. The fecal sediment revealed a large (180 µm x 90 µm) oval egg with a small operculum. This parasite probably is:

Name the parasite shown in the following image:

Name the parasite shown in the following image: