parasit Flashcards
(60 cards)
1
Q
- Enterobius vermicularis infection is
usually diagnosed by finding
A. Eggs in perianal specimens
B. Larvae in perianal specimens
C. Larvae in feces
D. Eggs in the feces
A
A. Eggs in perianal specimens
2
Q
- The best direct diagnosis of Echinococcus
granulosus infection in humans is made
by identification of
A. Adult worms in the intestine
B. Adult worms in tissues
C. Eggs in feces
D. Hydatid cysts in tissues
A
D. Hydatid cysts in tissues
3
Q
- Which statement is correct for specimen
collection and processing?
A. Stool samples can contain urine.
B. Stools can be frozen without affecting
parasitic structure.
C. Liquid stools are best for detecting
ameba and flagellate trophozoites.
D. Unpreserved stools can remain at
room temperature for up to 72 hours.
A
C. Liquid stools are best for detecting
ameba and flagellate trophozoites.
4
Q
- Cysts are the infective stage of this
intestinal flagellate.
A. Balantidium coli
B. Dientamoebafragilis
C. Entamoeba coli
D. Giardia lamblia
A
D. Giardia lamblia
5
Q
- Eggs or larvae recovered in the stool are
not routinely used to diagnose infections
caused by which one of the following
helminths?
A. Trichinella spiralis
B. Strongyloides stercomlis
C. Necator americanus
D. Ascaris lumbricoides
A
A. Trichinella spiralis
6
Q
- Many parasites have different stages of
growth within different hosts. The host
where the sexual reproductive stage of the
parasites exists is called the
A. Commensal
B. Definitive host
C. Intermediate host
D. Vector
A
B. Definitive host
7
Q
- Species identification of an immature
amebic cyst can be very difficult. The
presence of a large glycogen mass is
sometimes seen in
A. Dientamoebafragilis
B. Endolimax nana
C. Entamoeba coli
D. Entamoeba histolytica
A
C. Entamoeba coli
8
Q
- Which of the following is typical in cysts
of lodamoeba biitschlii?
A. A glycogen mass
B. Blunt chromatoidal bars
C. Four nuclei with large karyosomes
D. Many ingested bacteria
A
A. A glycogen mass
9
Q
- Which of the following is the most
important feature in differentiating cysts
of Entamoeba histolytica from E. dispar?
A. Number of nuclei
B. Size of the cyst
C. Shape of the karyosome
D. Distinguishing surface antigens by
immunologic assays
A
D. Distinguishing surface antigens by
immunologic assays
10
Q
- Which of the following findings in a
peripheral blood smear is especially
associated with tissue-invading helminths
but may also be found in a variety of
allergic conditions and other diseases?
A. Eosinophilia
B. Leukopenia
C. Lymphocytosis
D. Neutropenia
A
A. Eosinophilia
11
Q
11 . A 48-year-old man from Texas developed
fever and weakness 16 days after a
hunting trip in northwest Tanzania.
Several days after the onset of fever, he
noticed a raised, tender, erythematous
nodule (6-8 cm in diameter) on the
posterior aspect of his right arm. He was
hospitalized in Africa and treated for
5 days with a cephalosporin for presumed
cellulitis. After little improvement, he
returned to Texas. On arrival, the patient
had a temperature of 38.9°C (102°F), a
morbilliform rash of the trunk, and rightsided, anterior cervical lymphadenopathy.
Cerebrospinal fluid contained 12 red cells
and 18 mononuclear cells/uL and a normal
protein level (32 mg/dL). Laboratory tests
of peripheral blood revealed a hemoglobin
level of 107 g/L, a white cell count of
2.4 X 109/L, and a platelet count of
75 X 109/L. The diagnosis was made by
finding the extracellular flagellate parasite
in a peripheral blood smear. Which of the
following is the most probable etiologic
agent of this infection?
A. Leishmania donovani
B. Trypanosoma brucei
C. Tiypanosoma cruzi
D. Toxoplasma gondii
A
B. Trypanosoma brucei
12
Q
- Which species of malaria parasite usually
has ameboid trophozoites and produces
small reddish dots in the red blood cell
cytoplasm?
A. Plasmodium knowlesi
B. Plasmodium falciparum
C. Plasmodium malariae
D. Plasmodium vivax
A
D. Plasmodium vivax
13
Q
- With a fecal specimen, which one of the
following is the most dependable
procedure for the accurate, specific
diagnosis of an intestinal amebic
infection?
A. Direct saline wet mount
B. Direct iodine wet mount
C. Permanently stained smear
D. Formalin-ethyl acetate sedimentation
technique
A
C. Permanently stained smear
14
Q
- In an examination of stained blood films,
Babesia spp. are likely to resemble
A. Leishmania donovani
B. Plasmodium falciparum
C. Toxoplasma gondii
D. Trypanosoma cruz
A
B. Plasmodium falciparum
15
Q
- Which of the following is a mercury-containing fixative used to preserve
parasites in stool specimens?
A. Formalin
B. Sodium acetate
C. Buffered glycerol
D. Polyvinyl alcohol
A
D. Polyvinyl alcohol
16
Q
- Examination of a fecal smear following
acid-fast stain reveals round acid-fast
positive structures 8-10 um in diameter.
You should suspect
A. Cryptosporidium
B. Cyclospora
C. Isospora
D. Microsporidia
A
B. Cyclospora
17
Q
- A 22-year-old male presents to his family
physician complaining of fatigue, muscle
pain, periorbital edema, and fever. He
denies travel outside the U.S. The
physician suspects infectious mononucleosis; however, serologic tests for infectious mononucleosis are negative. The
complete blood count revealed a slightly
elevated white blood count, and there were
10% eosinophils on the differential.
Which of the following should be
considered part of the differential
diagnosis?
A. Ascaris lumbricoides
B. Taenia solium
C. Trichinella spiralis
D. Trypanosoma cruzi
A
C. Trichinella spiralis
18
Q
- Which Schistosoma species has a large
terminal spine?
A. S. haematobium
B. S.japonicum
C. S. mansoni
D. S. mekongi
A
A. S. haematobium
19
Q
- Elephantiasis is a complication associated
with which of the following?
A. Cysticercosis
B. Guinea worm
C. Hydatid cyst disease
D. Filariae
A
D. Filariae
20
Q
- A patient with history of human immunodeficiency virus infection presents with a
5-day history of diarrhea and weight loss.
A series of stool specimens is collected
and examined for the presence of ova and
parasites. An acid-fast stain on direct
smear reveals pink-stained round
structures approximately 4 (am in
diameter. The most likely pathogen is
A. Blastocystis hominis
B. Cryptosporidium sp.
C. Isospora sp.
D. Microsporidium
A
B. Cryptosporidium sp.
21
Q
- A 55-year-old female presents to her
physician complaining of a fever that
“comes and goes” and fatigue. A complete
blood count reveals decreased red blood
cell count and hemoglobin. History
reveals the patient recently traveled
through Europe and Africa. You should
suspect
A. Cutaneous larval migrans
B. Filariasis
C. Malaria
D. Trichinella
A
C. Malaria
22
Q
- The disease most commonly associated
with Acanthamoeba sp. is
A. Diarrhea
B. Keratitis
C. Liver abscess
D. Meningoencephalitis
A
B. Keratitis
23
Q
- A modified trichrome stain of a fecal
smear can be used to detect microsporidia.
Which of the following would describe the
appearance of this parasite in this stain?
A. Purple circles, 10-15 um in diameter
B. Pink ovals, 1-3 urn in diameter
C. Blue ovals, 4-6 urn in diameter
D. Fluorescent circles, 8-12 um in
diameter
A
B. Pink ovals, 1-3 urn in diameter
24
Q
- Hydatid cysts in humans are due to
ingestion of a tapeworm stage normally
found in canines. This stage is the
A. Cercaria
B. Cercocystis
C. Cysticercus
D. Embryonated egg
A
D. Embryonated egg
25
25. Oocysts, the infective stage of Toxoplasma
gondii, is found in
A. Cat feces
B. Human feces
C. Undercooked pork
D. Undercooked beef
A. Cat feces
26
26. A 15-um pear-shaped flagellate with a
visible parabasal body and "falling leaf"
motility in a direct saline mount of a
diarrheal stool specimen is most probably
A. Balantidium coli
B. Chilomastix mesnili
C. Giardia lamblia
D. Trichomonas hominis
C. Giardia lamblia
27
27. This parasitic infection may result in
vitamin B]2 deficiency, and individuals
with pernicious anemia are predisposed
to more severe symptoms.
A. Diphyllobothrium latum
B. Echinococcus granidosus
C. Hymenolepis diminuta
D. Taenia saginata
A. Diphyllobothrium latum
28
28. Knowledge of nocturnal periodicity is
especially important in the diagnosis of
certain infections caused by
A. Babesia
B. Plasmodium
C. Microfilariae
D. Trypanosoma
C. Microfilariae
29
29. For which of the following diseases is
close contact with an infected human host
the most important mechanism of
transmission?
A. Schistosomiasis
B. Toxoplasmosis
C. Trichinosis
D. Trichomoniasis
D. Trichomoniasis
30
30. Which of the following helminths
produces an elongate, barrel-shaped egg
(50 X 22 |xm) with a colorless polar plug
at each end?
A. Ascaris lumbricoides
B. Hymenolepis nana
C. Necator americanus
D. Trichuris trichiura
D. Trichuris trichiura
31
31. Which species of Plasmodium may
readily be identified when crescent-shaped
gametocytes are found in stained blood
films?
A. P. falciparum
B. P. malariae
C. P. ovale
D. P. vivax
A. P. falciparum
32
32. Cysts of Giardia lamblia
A. Contain four nuclei
B. Are motile by flagella
C. Have an undulating membrane
D. Are rarely found in stool specimens
A. Contain four nuclei
33
33. Migration of larva through the skin can
sometimes produce allergic reactions called
larva migrans; this is associated with
A. Strongyloides stercoralis
B. Dracunculus medinensis
C. Onchocerca volvulus
D. Loa loa
A. Strongyloides stercoralis
34
34. A free-living ameba that causes primary
amebic meningoencephalitis is
A. Dientamoeba fragilis
B. Entamoeba coli
C. Entamoeba histolytica
D. Naegleria fowleri
D. Naegleria fowler
35
35. Decontamination of drinking water, fruits,
and vegetables before consumption is
necessary in countries without welldeveloped public sanitation. Which of the
following diseases would probably be
least affected by that kind of precaution?
A. Amebiasis
B. Ascariasis
C. Filariasis
D. Giardiasis
C. Filariasis
36
36. Which stage of Taenia saginata is usually
infective for humans?
A. Cysticercus larva
B. Embryonated egg
C. Filariform larva
D. Rhabditiform larva
A. Cysticercus larva
37
37. This amebic cyst has an average size of
6-8 um and is usually spherical. When
mature, it has four nuclei, but immature
cysts with one or two nuclei are often
seen. The nuclei have fine uniform
granules of peripheral chromatin and
small, discrete, usually central
karyosomes. Chromatoidal bars with
bluntly rounded ends are sometimes
present. Name the species.
A. Endolimax nana
B. Entamoeba coli
C. Entamoeba hartmanni
D. Entamoeba histolytica
C. Entamoeba hartmanni
38
38. Which stage of Trichuris trichiura is
infective for humans?
A. Proglottid
B. Filariform larva
C. Rhabditiform larva
D. Embryonated ovum
D. Embryonated ovum
39
39. An intestinal parasite is seen in an iodinestained fecal wet mount that is described
as being 25 (Jim in diameter with a
homogenously stained central body
surrounded by a thin ring of cytoplasm
containing a number of nuclei. This best
describes
A. Blastocystis hominis
B. Endolimax nana
C. Entamoeba dispar
D. lodamoeba btitschlii
A. Blastocystis hominis
40
40. Sanitary disposal of human feces is the
most important factor in decreasing the
incidence of most infections caused by
intestinal parasites. Which of the
following diseases would not be affected
by that kind of sanitation?
A. Ascariasis
B. Taeniasis
C. Trichinosis
D. Hookworm infection
C. Trichinosis
40
41. Which species of Plasmodium is characterized by the presence of Schiiffner's dots
in the infected erythrocytes?
A. Plasmodiumfalciparum
B. Plasmodium knowlesi
C. Plasmodium malariae
D. Plasmodium ovale
D. Plasmodium ovale
41
42. Which of the following is the largest
intestinal protozoa infecting humans?
A. Balantidium coli
B. Dientamoeba frag His
C. Entamoeba histolytica
D. Giardia lamblia
A. Balantidium coli
42
43. The rhabditiform larvae of Strongyloides
stercoralis
A. Mate and produce ova
B. Are infective for humans
C. Are the diagnostic form found in feces
D. Are found in the blood of infected
humans
C. Are the diagnostic form found in feces
43
44. Which species of Plasmodium can have
exoerythrocytic stages capable of causing
relapses months or years after initial
infection?
A. P. falciparum
B. P. ovale
C. P. malariae
D. P. cynomolgi
B. P. ovale
44
45. A Giemsa-stained thick blood film showed
many ring forms with no older stages, and
a number of the rings had double
chromatin dots. These findings are
characteristic of
A. Plasmodium falciparum
B. Plasmodium vivax
C. Plasmodium malariae
D. Plasmodium ovale
A. Plasmodium falciparum
45
46. Which of the following nematode
parasites is acquired from eating inadequately cooked, infected pork?
A. Strongyloides stercoralis
B. Taenia saginata
C. Taenia solium
D. Trichinella spiralis
D. Trichinella spiralis
46
47. Which of the following pairs of helminths
cannot be reliably differentiated by the
appearance of their eggs?
A. Ascaris lumbricoides and Necator
americanus
B. Hymenolepis nana and H. diminuta
C. Necator americanus and Ancylostoma
duodenale
D. Diphyllobothrium latum and Fasciola
hepatica
C. Necator americanus and Ancylostoma
duodenale
47
48. Which of the following forms of
Toxoplasma gondii are produced in
infected humans?
A. Bradyzoites
B. Macrogametes
C. Sporoblasts
D. Oocysts
A. Bradyzoites
48
49. Hematuria is a typical sign of human
infection caused by
A. Trypanosoma cruzi
B. Trichinella spiralis
C. Trichomonas vaginalis
D. Schistosoma haematobium
D. Schistosoma haematobium
49
50. Which of the following is the vector for
Babesia?
A. Fleas
B. Lice
C. Ticks
D. Mosquitoes
C. Ticks
50
51. Chagas disease (American trypanosomiasis) is caused by
A. Tiypanosoma brucei
B. Trypanosoma cruzi
C. Leishmania braziliensis
D. Dracunculus medinensis
B. Trypanosoma cruzi
51
52. Which of the following is the preferred
anticoagulant for preparing blood smears
for diagnosing malaria?
A. EDTA
B. Heparin
C. Sodium citrate
D. Sodium fluoride
A. EDTA
52
53. Refer to Color Plate 38*. This is a
photomicrograph of a trichrome stain
of a fecal smear, magnification 400 X.
The parasite measures 65 X 45 um. What
is the identification of this parasite?
A. Balantidium coli
B. Diphyllobothrium latum
C. Giardia lamblia
D. Schistosoma japonicum
A. Balantidium coli
53
54. Refer to Color Plate 39 *. This is a
photomicrograph of an iodine wet prep
made from a stool sample; magnification
is 400 X. The ovum is about 70 X 50 um.
What is the identification of the parasite?
A. Hookworm
B. Enterobius vermicularis
C. Trichuris trichiura
D. Ascaris lumbricoides
D. Ascaris lumbricoides
54
55. Refer to Color Plate 40*. This is a photomicrograph of an iron hematoxylin stain
from a fecal smear. The magnification is
1000X. The parasite is approximately
20 um long and 15 um wide. What is the
identification of this parasite?
A. Chilomastix mesnili trophozoite
B. Giardia lamblia trophozoite
C. Trichomonas hominis trophozoite
D. Trichomonas tenax trophozoite
B. Giardia lamblia trophozoite
55
56. Refer to Color Plate 41 *. This is a photomicrograph of an iron hematoxylin stain
from a fecal smear. The magnification is
1000X. The parasite is approximately
12 um in diameter. What is the identification of this parasite?
A. Entamoeba histolytica trophozoite
B. Entamoeba hartmanni trophozoite
C. Dientamoebafragilis trophozoite
D. Entamoeba coli trophozoite
C. Dientamoeba fragilis trophozoite
56
57. Refer to Color Plate 42 *. This is a photomicrograph of an iodine wet-mount from
a fecal sample. The magnification is
1000X. The parasite is approximately
25 um in diameter. What is the identification of this parasite?
A. Entamoeba histolytica cyst
B. Entamoeba histolytica trophozoite
C. Entamoeba coli cyst
D. Entamoeba coli trophozoite
C. Entamoeba coli cyst
57
58. Refer to Color Plate 43*. This is a photomicrograph of an iodine wet mount from
a fecal sample. The magnification is 400X.
The ovum is approximately 70 X 38 um.
What is the identification of this parasite?
A. Hookworm
B. Ascaris lumbricoides
C. Diphyllobothrium latum
D. Taenia solium
A. Hookworm
58
59. Refer to Color Plate 44*. This is a photomicrograph of a trichrome stain from a
fecal smear. The magnification is 1000X.
The parasite is approximately 15 (urn in
diameter. What is the identification of this
parasite?
A. Entamoeba hartmanni
B. Dientamoeba fragilis
C. lodamoeba biltschlii
D. Blastocystis hominis
D. Blastocystis hominis
59
60. Refer to Color Plate 45 B. This is a photomicrograph of a blood smear stained with
Wright's stain. Identify the parasite.
A. Babesia sp.
B. Plasmodium malariae
C. Plasmodium falciparum
D. Trypanosoma cruzi
B. Plasmodium malariae
