Deck 46: Laboratory Methods for Diagnosis of Parasitic Infections

Question 1

An amoebic trophozoite that can be described as 12 to 15 microns, with no nuclear peripheral chromatin, a large karyosome, and coarsely granular and highly vacuolated cytoplasm would most likely be

A)Entamoeba histolytica.
B)E.coli.
C)Iodamoeba bütschlii.
D)E.hartmanni.

Answer 1

C
The characteristics listed are those of Iodamoeba bütschlii.

Question 2

The direct wet mount as part of the O&P (ova and parasite) examination

A)requires freshly passed, unpreserved stool.
B)is designed to allow detection of motile helminth ova.
C)is examined microscopically at low, high dry, and oil immersion magnifications.
D)is performed for specimens received in the laboratory in stool collection preservatives.
E)All of the above are correct.

Answer 2

A
The O&P examination comprises three separate protocols: the direct wet mount, the concentration, and the permanent stained smear. The direct wet mount requires fresh stool, is designed to allow detection of motile protozoan trophozoites, and is examined microscopically at low and high dry magnifications.

Question 3

The concentration part of the O&P (ova and parasite) examination

A)requires freshly passed, unpreserved stool.
B)is designed to allow detection of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae.
C)is examined microscopically at low, high dry, and oil immersion magnifications.
D)is designed to facilitate identification of intestinal protozoa.
E)All of the above are correct.

Answer 3

B
The O&P examination comprises three separate protocols: the direct wet mount, the concentration, and the permanent stained smear. The second part of the O&P is the concentration, which is designed to facilitate recovery of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae. Both flotation and sedimentation methods are available; the most common procedure is the formalin-ethyl acetate sedimentation method (formerly called the formalin-ether method). The concentrated specimen is examined as a wet preparation, with or without iodine, using low and high dry magnifications (´100, ´400) as indicated for the direct wet smear examination.

Question 4

The specimen of choice for diagnosing infection with Leishmania spp is

A)feces.
B)blood smear.
C)liver tissue.
D)CSF.

Question 5

The permanent stained smear part of the O&P (ova and parasite) examination

A)requires freshly passed, unpreserved stool.
B)is designed to allow detection of protozoan cysts, coccidian oocysts, microsporidial spores, and helminth eggs and larvae.
C)is examined microscopically at low, high dry, and oil immersion magnifications.
D)is designed to facilitate identification of intestinal protozoa.
E)All of the above are correct.

Question 6

A flagellate trophozoite that can be described as 9 to 12 μm, with one to two nuclei with no nuclear peripheral chromatin, a karyosome composed of four to eight large granules, and finely granular cytoplasm would most likely be

A)Giardia lamblia.
B)Dientamoeba fragilis.
C)Iodamoeba bütschlii.
D)Chilomastix mesnili.

Question 7

The Schistosoma species with a prominent lateral spine is

A)Schistosoma japonicum.
B)Schistosoma haematobium.
C)Schistosoma mansoni.
D)Schistosoma westermani.

Question 8

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Plasmodium falciparum

Question 9

A red blood cell parasite that can be described as infecting younger RBCs, having Schüffner's dots, presenting in all stages, and having 12 to 24 merozoites would most likely be

A)Plasmodium malariae.
B)Plasmodium vivax.
C)Plasmodium falciparum.
D)Babesia microti.

Question 10

When amebiasis is strongly indicated but no parasitic forms are detected from any of three submitted fecal samples, the next step might be

A)to diagnose based on clinical findings and begin treatment.
B)to collect material obtained from sigmoidoscopy and examine for parasites.
C)to collect another series of three fecal samples and submit for parasitic examination.
D)to collect duodenal drainage and examine for parasites.

Question 11

A red blood cell parasite that can be described as infecting older and younger RBCs, presenting in mostly young ring forms, and having a crescent-shaped or banana gametocyte would most likely be

A)Plasmodium malariae.
B)Plasmodium vivax.
C)Plasmodium falciparum.
D)Babesia microti.

Question 12

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Trichomonas vaginalis

Question 13

Sputum may be submitted for examination for which parasite?

A)Ascaris lumbricoides
B)Strongyloides stercoralis
C)Paragonimus westermani
D)Echinococcus granulosus
E)All of the above are correct.

Question 14

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Cryptosporidium spp.

Question 15

The most common larvae found in stool specimens is

A)Ascaris lumbricoides.
B)Strongyloides stercoralis.
C)Paragonimus westermani.
D)Naegleria fowleri.

Question 16

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Isospora belli

Question 17

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Paragonimus westermani

Question 18

The examination of spinal fluid may reveal the parasitic agent of meningoencephalitis called

A)Ascaris lumbricoides.
B)Strongyloides stercoralis.
C)Paragonimus westermani.
D)Naegleria fowleri.

Question 19

The eggs of which intestinal parasite are not commonly found in feces and must be detected by other diagnostic techniques?

A)Giardia lamblia
B)Cryptosporidium parvum
C)Clonorchis sinensis
D)Enterobius vermicularis

Question 20

An amoebic trophozoite that can be described as 15 to 20 microns, with fine uniform nuclear peripheral chromatin, central karyosome, and finely granular cytoplasm would most likely be

A)Entamoeba histolytica.
B)E.coli.
C)Iodamoeba bütschlii.
D)E.hartmanni.

Question 21

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Giardia lamblia

Question 22

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Toxoplasma gondii

Question 23

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Naegleria fowleri

Question 24

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Ascaris lumbricoides

Question 25

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Enterobius vermicularis

Question 26

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Iodamoeba bütschlii

Question 27

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Trypanosoma cruzi

Question 28

Match the parasite with the best diagnostic specimen type.a.Feces
b.Blood smear
c.Vaginal secretions
d.CSF
e.Skin scraping
Entamoeba histolytica

Question 29

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Strongyloides stercoralis

Question 30

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Trichinella spiralis

Question 31

Match the parasite with the best diagnostic specimen type.a.Rectal tape prep
b.Tissue biopsy
c.Sputum
d.Feces
e.Blood smear
Taenia solium