CIULLA Flashcards
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
Eggs in perianal specimens
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
Eggs in feces
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.
Liquid stools are best for detecting ameba and flagellate trophozoites.
Cysts are the infective stage of this intestinal flagellate.
A. Balantidium coli
B. Dientamoeba fragilis
C. Entamoeba coli
D. Giardia lamblia
Dientamoeba fragilis
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
Necator americanus
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
Definitive host
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
Entamoeba histolytica
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 glycogen mass
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
Distinguishing surface antigens by immunologic assays
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
Lymphocytosis
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 right-
sided, 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
Trypanosoma brucei
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
Plasmodium vivax
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
Permanently stained smear
In an examination of stained blood films, Babesia spp. are likely to resemble
A. Leishmania donovani
B. Plasmodiumfalciparum
C. Toxoplasma gondii
D. Trypanosoma cruzi%
Plasmodium falciparum
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
Polyvinyl alcohol
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. Cyclospom
C. Isospora
D. Microsporidia
Cyclospom
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
Trichinella spiralis
Which Schistosoma species has a large terminal spine?
A. S. haematobium
B. S.japonicum
C. S. mansoni
D. S. mekongi
S. mansoni
Elephantiasis is a complication associated with which of the following?
A. Cysticercosis
B. Guinea worm
C. Hydatid cyst disease
D. Filariae
Filariae
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
Cryptosporidium spp.
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
Filariasis
The disease most commonly associated with Acanthamoeba sp. is
A. Diarrhea
B. Keratitis
C. Liver abscess
D. Meningoencephalitis
Keratitis
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
Pink ovals, 1-3 urn in diameter
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
Cercaria
Oocysts, the infective stage of Toxoplasma gondii, is found in
A. Cat feces
B. Human feces
C. Undercooked pork
D. Undercooked beef
Undercooked beef
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
Trichomonas hominis
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
Diphyllobothrium latum
Knowledge of nocturnal periodicity is especially important in the diagnosis of certain infections caused by
A. Babesia
B. Plasmodium
C. Microfilariae
D. Trypanosoma
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
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
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
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
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 free-living ameba that causes primary amebic meningoencephalitis is
A. Dientamoebafragilis
B. Entamoeba coli
C. Entamoeba histolytica
D. Naegleriafowleri
Decontamination of drinking water, fruits, and vegetables before consumption is necessary in countries without well-
developed 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
Which stage of Taenia saginata is usually infective for humans?
A. Cysticercus larva
B. Embryonated egg
C. Filariform larva
D. Rhabditiform larva
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
Which stage of Trichuris trichiura is infective for humans?
A. Proglottid
B. Filariform larva
C. Rhabditiform larva
D. Embryonated ovum
An intestinal parasite is seen in an iodine-stained 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
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
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
Which of the following is the largest intestinal protozoa infecting humans?
A. Balantidium coli
B. Dientamoeba frag His
C. Entamoeba histolytica
D. Giardia lamblia
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
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
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
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
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
Which of the following forms of Toxoplasma gondii are produced in infected humans?
A. Bradyzoites
B. Macrogametes
C. Sporoblasts
D. Oocysts
Hematuria is a typical sign of human infection caused by
A. Trypanosoma cruzi
B. Trichinella spiralis
C. Trichomonas vaginalis
D. Schistosoma haematobium
Which of the following is the vector for Babesia?
A. Fleas
B. Lice
C. Ticks
D. Mosquitoes
Chagas disease (American trypanosomiasis) is caused by
A. Tiypanosoma brucei
B. Trypanosoma cruzi
C. Leishmania braziliensis
D. Dracunculus medinensis
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
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
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
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
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
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
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
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
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. Plasmodiumfalciparum
D. Trypanosoma cruzi
