Question 1

Visceral leishmaniasis is caused by:&#10;A) Trypanosoma brucei gambience&#10;B) Trypanosoma cruzi&#10;C) Leishmania braziliensis&#10;D) Leishmania donovani

Accepted Answer

L. donovani invades internal organs, causing visceral leishmaniasis. The other Leishmania species cause diffuse cutaneous leishmaniasis.

Question 2

Name the parasite shown in the following image:  &#10;A) Plasmodium falciparum&#10;B) Trypanosoma brucei rhodiense&#10;C) Trypanosoma brucei gambiense&#10;D) Trypanosoma cruzi

Accepted Answer

This view shows a Trypanosoma cruzi trypanosome form in the blood. This parasite is differentiated by its sharply curved appearance. Additional information concerning the geographic origin of the patient is helpful when identifying this organism.

Question 3

A forty-year-old immigrant from Bangladesh presented with splenomegaly and hepatomegaly. When questioned, the patient stated that he had diarrhea, dysentery, and weight loss a year or so ago, before coming to the United States. Since that time, he had become easily fatigued and felt weak. These symptoms suggest prior infection with which of the following parasites?

A) Trypanosoma brucei gambience
B) Trypanosoma cruzi
C) Leishmania braziliensis
D) Leishmania donovani

Leishmania donovani

Accepted Answer

L. donovani invades internal organs, causing visceral leishmaniasis. The other Leishmania species cause diffuse cutaneous leishmaniasis. LD bodies are found in infected organ tissues. Biopsies of this patient's enlarged organs would confirm the diagnosis.

Question 4

A traveler returning from a trip to the Andes Mountains in Central America noticed the formation of a boil on his lower leg. His physician opened the lesion and sent the purulent material to the lab for analysis. A stained preparation of the submitted material is shown here. Name the parasitic form seen in this view:

A) Amastigote form
B) Leptomastigote form
C) Promastigote form
D) Trypomastigote form

Accepted Answer

The amastigote form is found in the primary local lesions of the skin for all Leishmannia spp. For L. Donovani, amastigote forms invade internal organs, causing visceral leishmaniasis. The other Leishmania species cause diffuse cutaneous leishmaniasis. LD bodies are found in infected organ tissues. Biopsies of this patient's enlarged organs would confirm the diagnosis. The promastigote form is found in the sandfly vector. The trypanosome form is found in the blood stream for T. cruzi, with amastigote forms found in tissue macrophages.

Question 5

Name the parasite shown in the following image:  &#10;A) Chilomastix mesnili&#10;B) Enteromonas hominis&#10;C) Giardia lamblia&#10;D) Trichomonas vaginalis

Accepted Answer

This view is of the flagellate Giardia lamblia. The other parasites are identified by size, shape, nuclear characteristics, and the location in the host.

Question 6

Which of the following parasites was formerly thought to have no known cyst phase in its life cycle?&#10;A) Chilomastix mesnili&#10;B) Dientamoeba fragilis&#10;C) Enteromonas spp.&#10;D) Giardia lamblia

Accepted Answer

D. fragilis has been characterized as being the only protozoan parasite to have no known cyst, but now it has a documented, but rarely seen, cyst. Because all other trophozoites have only one nucleus, care must be taken to not confuse the D. fragilis trophozoite with another parasitic cyst.

Question 7

The most appropriate sample type and collection schedule for diagnosing Giardia lamblia is:&#10;A) One stool specimen&#10;B) Two stool specimens&#10;C) Three or more specimens collected on separate days&#10;D) Only one diarrheic stool specimen is needed.

Accepted Answer

G. lamblia (G. intestinalis) attaches to the intestinal lining of the host via its sucking disk. Due to this attachment, parasites are shed intermittently, so it is necessary to collect multiple specimens if this parasite is suspected and not recovered in early collections.

Question 8

Giardia intestinalis infection is acquired by:&#10;A) Ingesting contaminated food or water&#10;B) Swimming in fecally contaminated water&#10;C) . Walking barefoot in contaminated soil&#10;D) Either a or b

Accepted Answer

G. lamblia (G. intestinalis) infections are acquired by ingesting cysts from any contaminated food or water, or by transferring cysts from contaminated surfaces. Since Giardia spp. are resistant to chlorine, infections can be acquired by swimming in swimming pools as well as contaminated pond or river waters.

Question 9

The structure that is always visible in stained preparations of Balantidium coli trophozoites and cysts is:&#10;A) Cilia&#10;B) Ingested bacteria&#10;C) Macronucleus&#10;D) Micronucleus

Accepted Answer

The macronucleus is always visible in stained preparations of B. coli, but any or all of the other choices may be visible in any preparation.

Question 10

Name the parasite shown in the following image:  &#10;A) Chilomastix mesnili&#10;B) Enteromonas hominis&#10;C) Giardia lamblia&#10;D) Trichomonas vaginalis

Accepted Answer

This view is of the flagellate Trichomonas vaginalis. T. vaginalis appears slightly larger than leukocytes, and the whipping motion of the flagella is clearly visible in fresh, unstained urine. The other parasites are identified by size, shape, nuclear characteristics, and the location in the host.

Deck 5: Protozoa: The Hemoflagellates Trypanosoma SPP , Leishmania SPP, Flagellates and Ciliates