ROBERT HARR Flashcards
In a patient with diarrhea, occasionally Entamoeba histolytica/E. dispar (four nucleated cysts, no chromatoidal bars) are identified as being present; however, these cells, which are misdiagnosed as protozoa, are really:
A. Macrophages
B. Polymorphonuclear leukocytes
C. Epithelial cells
D. Eosinophils
Polymorphonuclear leukocytes
Charcot–Leyden crystals in stool may be associated with an immune response and are thought to be formed from the breakdown products of:
A. Neutrophils
B. Eosinophils
C. Monocytes
D. Lymphocytes
Eosinophils
The incorrect match between organism and the appropriate diagnostic procedure is:
A. Onchocerca volvulus—examination of skin snips
B. Cryptosporidium—modified acid-fast stain
C. Echinococcus granulosus—routine ova and parasite examination
D. Schistosoma haematobium—examination of urine sediment
Echinococcus granulosus—routine ova and parasite examination
Parasitic organisms that are most often transmitted sexually include:
A. Entamoeba gingivalis
B. Dientamoeba fragilis
C. Trichomonas vaginalis
D. Diphyllobothrium latum
Trichomonas vaginalis
The incorrect match between the organism and one method of acquiring the infection is:
A. Trypanosoma brucei rhodesiense—bite of sand fleas
B. Giardia lamblia—ingestion of water contaminated with cysts
C. Hookworm—skin penetration of larvae from soil
D. Toxoplasma gondii—ingestion of raw or rare meats
Trypanosoma brucei rhodesiense—bite of sand fleas
Upon examination of stool material for
Cystoisospora belli, one would expect to see:
A. Cysts containing sporozoites
B. Precysts containing chromatoidal bars
C. Oocysts that are modified acid-fast variable
D. Sporozoites that are hematoxylin positive
Oocysts that are modified acid-fast variable
Which specimen is the least likely to provide
recovery of Trichomonas vaginalis?
A. Urine
B. Urethral discharge
C. Vaginal discharge
D. Feces
Feces
Which of the following is the best technique to
identify Dientamoeba fragilis in stool?
A. Formalin concentrate
B. Trichrome-stained smear
C. Modified acid-fast–stained smear
D. Giemsa’s stain
Trichrome-stained smear
One of the following protozoan organisms has
been implicated in waterborne and foodborne
outbreaks within the United States. The suspect organism is:
A. Pentatrichomonas hominis
B. Dientamoeba fragilis
C. Giardia lamblia
D. Balantidium coli
Giardia lamblia
A Gram stain from a gum lesion showed what
appeared to be amoebae. A trichrome smear
showed amoebae with a single nucleus and
partially digested PMNs. The correct
identification is:
A. Trichomonas tenax
B. Entamoeba histolytica/E. dispar
C. Entamoeba gingivalis
D. Entamoeba polecki
Entamoeba gingivalis
An Entamoeba histolytica trophozoite has the
following characteristics:
A. Central karyosome in the nucleus, ingested
RBCs, and clear pseudopodia
B. Ingested RBCs, clear pseudopodia, and uneven chromatin on the nuclear membrane
C. Ingested RBCs, clear pseudopodia, and large
glycogen vacuoles in cytoplasm
D. Large, blotlike karyosome, ingested white blood cells (WBCs), and granular pseudopods
Central karyosome in the nucleus, ingested
RBCs, and clear pseudopodia
A 12-year-old girl is brought to the emergency
department with meningitis and a history of
swimming in a warm-water spring. Motile
amoebae that measure 10 μ in size are seen in
the CSF and are most likely:
A. Iodamoeba bütschlii trophozoites
B. Endolimax nana trophozoites
C. Dientamoeba fragilis trophozoites
D. Naegleria fowleri trophozoites
Naegleria fowleri trophozoites
Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:
A. Short buccal capsule and large genital
primordium
B. Long buccal capsule and pointed tail
C. Short buccal capsule and small genital
primordium
D. Small genital primordium and notch in tail
Short buccal capsule and large genital
primordium
Visceral larva migrans is associated with which of the following organisms?
A. Toxocara—serology
B. Onchocerca—skin snips
C. Dracunculus—skin biopsy
D. Angiostrongylus—CSF examination
Toxocara—serology
The following organisms are linked with
specific, relevant information. The incorrect
combination is:
A. Strongyloides stercoralis—internal autoinfection
B. Echinococcus granulosus—hydatid examination
C. Toxoplasma—serology
D. Balantidium coli—common within the
United States
Balantidium coli—common within the
United States
Examination of 24-hour unpreserved urine
specimen is sometimes helpful in the
recovery of:
A. Trichomonas vaginalis trophozoites
B. Schistosoma haematobium eggs
C. Enterobius vermicularis eggs
D. Strongyloides stercoralis larvae
Schistosoma haematobium eggs
The examination of sputum may be necessary to diagnose infection with:
A. Paragonimus westermani
B. Trichinella spiralis
C. Wuchereria bancrofti
D. Fasciola hepatica
Paragonimus westermani
Two helminth eggs that may resemble one
another are:
A. Diphyllobothrium latum and Paragonimus
westermani
B. Opisthorchis sinensis and Fasciolopsis buski
C. Taenia saginata and Hymenolepis nana
D. Ascaris lumbricoides and Trichostrongylus
Diphyllobothrium latum and Paragonimus
westermani
Eating poorly cooked pork can lead to an
infection with:
A. Taenia solium and Trichinella spiralis
B. Taenia saginata and Hymenolepis nana
C. Trichuris trichiura and Hymenolepis diminuta
D. Diphyllobothrium latum and Ascaris lumbricoides
Taenia solium and Trichinella spiralis
An operculated cestode egg that can be recovered from human feces is:
A. Clonorchis sinensis
B. Diphyllobothrium latum
C. Paragonimus westermani
D. Dipylidium caninum
Diphyllobothrium latum
The adult tapeworm of Echinococcus granulosus is found in the intestine of:
A. Dogs
B. Sheep
C. Humans
D. Cattle
Dogs
In infections with Taenia solium, humans can
serve as the:
A. Definitive host
B. Intermediate host
C. Either the definitive or the intermediate host
D. None of these options
Either the definitive or the intermediate host
Humans acquire infections with Diphyllobothrium latum adult worms by:
A. Ingestion of freshwater crabs
B. Skin penetration of cercariae
C. Ingestion of water chestnuts
D. Ingestion of raw freshwater fish
Ingestion of raw freshwater fish
Humans can serve as both the intermediate and definitive host in infections caused by:
A. Enterobius vermicularis
B. Hymenolepis nana
C. Schistosoma japonicum
D. Ascaris lumbricoides
Hymenolepis nana
Babesia has been implicated in disease from both splenectomized and nonsplenectomized patients. Morphologically, the parasites resemble:
A. Plasmodium falciparum rings
B. Leishmania donovani amastigotes
C. Trypanosoma cruzi trypomastigotes
D. Microsporidial spores
Plasmodium falciparum rings
Organisms (and infections) that under normal
conditions cannot be transmitted in the
laboratory are:
A. Cryptosporidium—cryptosporidiosis
B. Taenia solium—cysticercosis
C. Ascaris lumbricoides—ascariasis
D. Enterobius vermicularis—pinworm infections
Ascaris lumbricoides—ascariasis
Toxoplasma gondii is characterized by:
A. Possible congenital infection and ingestion of oocysts
B. Cosmopolitan distribution and possible
difficulties with interpretation of serological
results
C. Neither A nor B
D. Both A and B
Both A and B
Oocysts of Cryptosporidium spp. can be detected in stool specimens using:
A. Modified Ziehl–Neelsen acid-fast stain
B. Gram stain
C. Methenamine silver stain
D. Trichrome stain
Modified Ziehl–Neelsen acid-fast stain
Which microfilariae are usually not found
circulating in the peripheral blood?
A. Brugia malayi
B. Wuchereria bancrofti
C. Onchocerca volvulus
D. Loa loa
Onchocerca volvulus
Massive hemolysis, blackwater fever, and
central nervous system involvement are most
common with:
A. Plasmodium vivax
B. Plasmodium falciparum
C. Plasmodium ovale
D. Plasmodium malariae
Plasmodium falciparum
Organisms that should be considered in a nursery school outbreak of diarrhea include:
A. Endolimax nana, Giardia lamblia, and
Entamoeba coli
B. Giardia lamblia, Dientamoeba fragilis, and
Cryptosporidium spp.
C. Cryptosporidium spp., Trichomonas vaginalis, and Entamoeba coli
D. Pentatrichomonas hominis, Dientamoeba fragilis, and Endolimax nana
Giardia lamblia, Dientamoeba fragilis, and
Cryptosporidium spp.
The incorrect match between disease and
symptoms is:
A. Paragonimiasis—hemoptysis
B. Cryptosporidiosis—watery diarrhea
C. Toxoplasmosis in compromised host—central nervous system symptoms
D. Enterobiasis—dysentery
Enterobiasis—dysentery
The formalin–ether (ethyl acetate) concentration procedure for feces is used to demonstrate:
A. Motility of helminth larvae
B. Protozoan cysts and helminth eggs
C. Formation of amoebic pseudopods
D. Trophozoites
Protozoan cysts and helminth eggs
Cysts of Iodamoeba bütschlii typically have:
A. Chromatoidal bars with rounded ends
B. A heavily vacuolated cytoplasm
C. A large glycogen vacuole
D. Many ingested bacteria and yeast cells
A large glycogen vacuole
The miracidial hatching test helps to demonstrate the viability of eggs of:
A. Taenia species
B. Schistosoma species
C. Hookworm species
D. Opisthorchis species
Schistosoma species
Organisms that should be considered in a
waterborne outbreak of diarrheal disease include:
A. Giardia lamblia and Cryptosporidium spp.
B. Endolimax nana and Entamoeba histolytica
C. Blastocystis hominis and Trichomonas vaginalis
D. Toxoplasma gondii and Schistosoma mansoni
Giardia lamblia and Cryptosporidium spp.
Fecal immunoassays have become more commonly used to diagnose infections with:
A. Endolimax nana and Blastocystis hominis
B. Giardia lamblia and Cryptosporidium spp.
C. Ascaris lumbricoides and Trichuris trichiura
D. Strongyloides stercoralis and Trichomonas vaginalis
Giardia lamblia and Cryptosporidium spp.
Primary infections with the microsporidia may
originate in:
A. The lung
B. The nervous system
C. The gastrointestinal tract
D. Mucocutaneous lesions
The gastrointestinal tract
Eye infections with Acanthamoeba spp. have most commonly been traced to:
A. Use of soft contact lenses
B. Use of hard contact lenses
C. Use of contaminated lens care solutions
D. Failure to remove lenses while swimming
Use of contaminated lens care solutions
Select the most sensitive recovery method for
Acanthamoeba spp. from lens care solutions or corneal biopsies.
A. The trichrome staining method
B. The use of monoclonal reagents for the detection of antibody
C. The use of non-nutrient agar cultures seeded with Escherichia coli
D. The Giemsa’s stain method
The use of non-nutrient agar cultures seeded with Escherichia coli
The microsporidia are protozoans (now classified with the fungi) that have been implicated in human disease primarily in:
A. Immunocompromised patients
B. Pediatric patients under the age of 5 years
C. Adult patients with congenital
immunodeficiencies
D. Patients who have been traveling in the tropics
Immunocompromised patients
When staining Cystoisospora belli oocysts with
modified acid-fast stains, the important difference between these methods and the acid-fast stains used for acid-fast bacilli (AFB) is:
A. The staining time is much longer with regular AFB acid-fast stains
B. The decolorizer is weaker than acid alcohol used for AFB decolorizing
C. A counterstain must be used for the modified methods
D. The stain is more concentrated when staining for AFB
The decolorizer is weaker than acid alcohol used for AFB decolorizing
The incorrect match between symptoms and
disease is:
A. Dysentery—amebiasis
B. Malabsorption syndrome—giardiasis
C. Cardiac involvement—chronic Chagas disease
D. Myalgias—trichuriasis
Myalgias—trichuriasis
The incorrect match between organism and
characteristic is:
A. Chilomastix mesnili—Shepherd’s crook and
lemon shape
B. Plasmodium malariae—“band troph”
C. Hymenolepis nana—striated shell
D. Wuchereria bancrofti—sheathed microfilariae
Hymenolepis nana—striated shell
The incorrect match between method and method objective is:
A. Direct wet examination—detection of organism motility
B. Knott’s concentration—the recovery of
operculated helminth eggs
C. Baermann’s concentration—the recovery of
Strongyloides
D. Permanent stained fecal smear—confirmation of protozoa
Knott’s concentration—the recovery of
operculated helminth eggs
The incorrect match between organism and
characteristic is:
A. Dientamoeba fragilis—tetrad karyosome in the nucleus
B. Toxoplasma gondii—diagnostic serology
C. Echinococcus granulosus—daughter cysts
D. Schistosoma mansoni—egg with terminal spine
Schistosoma mansoni—egg with terminal spine
There are few procedures considered STAT in
parasitology. The most obvious situation would be:
A. Ova and parasite examination for giardiasis
B. Baermann’s concentration for strongyloidiasis
C. Blood films for malaria
D. Culture of amoebic keratitis
Blood films for malaria
An immunosuppressed man has several episodes of pneumonia, intestinal pain, sepsis with gram-negative rods, and a history of military service in Southeast Asia 20 years earlier. The most likely cause is infection with:
A. Trypanosoma cruzi
B. Strongyloides stercoralis
C. Naegleria fowleri
D. Paragonimus westermani
Strongyloides stercoralis
In a pediatric patient, the recommended clinical specimen for recovery of Enterobius vermicularis is the:
A. Stool specimen
B. Sigmoidoscopy scrapings
C. Duodenal aspirates
D. Series of Scotch tape preparations
Series of Scotch tape preparations
Which parasite causes eosinophilic
meningoencephalitis, a form of larva
migrans causing fever, headache, stiff neck,
and increased cells in the spinal fluid?
A. Necator americanus
B. Angiostrongylus cantonensis
C. Ancylostoma braziliense
D. Strongyloides stercoralis
Angiostrongylus cantonensis
“Cultures of parasites are different from bacterial cultures; no quality control is needed.” This statement is:
A. True, if two tubes of media are set up for each patient
B. True, if the media are checked every 24 hours
C. False, unless two different types of media are used
D. False, and organism and media controls need to be set up
False, and organism and media controls need to be set up
Protozoan cysts were seen in a concentration
sediment and tentatively identified as Entamoeba coli. However, the organisms were barely visible on the permanent stained smear because:
A. The organisms were actually not present in the concentrate sediment
B. There were too few cysts to allow identification on the stained smear
C. E. coli cysts were present but poorly fixed
D. The concentrate and permanent stained smear were not from the same patient
E. coli cysts were present but poorly fixed
When humans have hydatid disease, the causative agent and host classification are:
A. Echinococcus granulosus—accidental
intermediate host
B. Echinococcus granulosus—definitive host
C. Taenia solium—accidental intermediate host
D. Taenia solium—definitive host
Echinococcus granulosus—accidental
intermediate host
A 45-year-old hunter developed fever, myalgia, and periorbital edema. He has a history of bear meat consumption. The most likely causative agent is:
A. Toxoplasma gondii
B. Taenia solium
C. Hymenolepis nana
D. Trichinella spiralis
Trichinella spiralis
In a condition resulting from the accidental
ingestion of eggs, the human becomes the
intermediate rather than the definitive host. The correct answer is:
A. Trichinosis
B. Cysticercosis
C. Ascariasis
D. Strongyloidiasis
Cysticercosis
A transplant patient on immunosuppressive
drugs developed increasing diarrhea. The most
likely combination of disease and diagnostic
procedure is:
A. Trichinosis and trichrome stain
B. Microsporidiosis and modified trichrome stain
C. Toxoplasmosis and Gram stain
D. Paragonimiasis and wet preparation
Microsporidiosis and modified trichrome stain
After returning from a 2-year stay in India, a
patient has eosinophilia, an enlarged left spermatic cord, and bilateral inguinal lymphadenopathy. The most likely clinical specimen and organism match is:
A. Thin blood films—Leishmania
B. Urine—concentration for Trichomonas vaginalis
C. Thin blood films—Babesia
D. Thick blood films—microfilariae
Thick blood films—microfilariae
Patients with severe diarrhea should use
“enteric precautions” to prevent nosocomial
infections with:
A. Giardia lamblia
B. Ascaris lumbricoides
C. Cryptosporidium spp.
D. Cystoisospora belli
Cryptosporidium spp.
A 60-year-old Brazilian patient with cardiac
irregularities and congestive heart failure suddenly dies. Examination of the myocardium revealed numerous amastigotes, an indication that the cause of death was most likely:
A. Leishmaniasis with Leishmania donovani
B. Leishmaniasis with Leishmania braziliense
C. Trypanosomiasis with Trypanosoma gambiense
D. Trypanosomiasis with Trypanosoma cruzi
Trypanosomiasis with Trypanosoma cruzi
When malaria smears are requested, what patient information should be obtained?
A. Diet, age, sex
B. Age, antimalarial medication, sex
C. Travel history, antimalarial medication, date of return to United States
D. Fever patterns, travel history, diet
Travel history, antimalarial medication, date of return to United States
In an outbreak of diarrheal disease traced to a municipal water supply, the most likely causative agent is:
A. Cryptosporidium spp.
B. Cystoisospora belli
C. Entamoeba histolytica
D. Dientamoeba fragilis
Cryptosporidium spp.
Within the United States, sporadic mini-outbreaks of diarrheal disease have been associated with the ingestion of strawberries, raspberries, fresh basil, mesclun (baby lettuce leaves), and snow peas. The most likely causative agent is:
A. Dientamoeba fragilis
B. Cyclospora cayetanensis
C. Schistosoma mansoni
D. Cystoisospora belli
Cyclospora cayetanensis
Which of the following statements is true
regarding onchocerciasis?
A. The adult worm is present in the blood
B. The microfilariae are in the blood during the late evening hours
C. The diagnostic test of choice is the skin snip
D. The parasite resides in the deep lymphatics
The diagnostic test of choice is the skin snip
The most prevalent helminth to infect humans is:
A. Enterobius vermicularis, the pinworm
B. Ascaris lumbricoides, the large intestinal
roundworm
C. Taenia saginata, the beef tapeworm
D. Schistosoma mansoni, one of the blood flukes
Enterobius vermicularis, the pinworm
A helminth egg is described as having terminal
polar plugs. The most likely helminth is:
A. Hookworm
B. Trichuris trichiura
C. Fasciola hepatica
D. Diphyllobothrium latum
Trichuris trichiura
Ingestion of which of the following eggs will result in infection?
A. Strongyloides stercoralis
B. Schistosoma japonicum
C. Toxocara canis
D. Opisthorchis sinensis
Toxocara canis
Plasmodium vivax and Plasmodium ovale are
similar because they:
A. Exhibit Schüffner’s dots and have a true relapse in the life cycle
B. Have no malarial pigment and multiple rings
C. Commonly have appliqué forms in the red cells
D. Have true stippling, do not have a relapse stage, and infect old red cells
Exhibit Schüffner’s dots and have a true relapse in the life cycle
The term internal autoinfection can be associated with the following parasites:
A. Cryptosporidium spp. and Giardia lamblia
B. Cystoisospora belli and Strongyloides stercoralis
C. Cryptosporidium spp. and Strongyloides stercoralis
D. Giardia lamblia and Cystoisospora belli
Cryptosporidium spp. and Strongyloides stercoralis
Microsporidia have been identified as causing
severe diarrhea, disseminated disease in other body sites, and ocular infections. Routes of infection have been identified as:
A. Ingestion
B. Inhalation
C. Direct contamination from the environment
D. Ingestion, inhalation, and direct contamination
Ingestion, inhalation, and direct contamination
An immunocompromised patient continues
to have diarrhea after repeated ova and
parasites (O&P) examinations (sedimentation
concentration, trichrome permanent stained
smear) were reported as negative; organisms
that might be responsible for the diarrhea
include:
A. Cryptosporidium spp., Giardia lamblia,
and Cystoisospora belli
B. Giardia lamblia, microsporidia, and
Endolimax nana
C. Taenia solium and Endolimax nana
D. Cryptosporidium spp. and microsporidia
Cryptosporidium spp. and microsporidia
Confirmation of an infection with microsporidia can be achieved by seeing:
A. The oocyst wall
B. Sporozoites within the spore
C. Evidence of the polar tubule
D. Organisms stained with modified acid-fast stains
Evidence of the polar tubule
Early ring stages of the fifth human malaria,
Plasmodium knowlesi, resemble those of:
A. Plasmodium malariae
B. Plasmodium ovale
C. Plasmodium falciparum
D. Plasmodium vivax
Plasmodium falciparum
Parasite stages that are immediately infective for humans on passage from the gastrointestinal tract include:
A. Schistosoma spp. eggs
B. Toxoplasma gondii bradyzoites
C. Giardia lamblia trophozoites
D. Cryptosporidium spp. oocysts
Cryptosporidium spp. oocysts
Older developing stages (trophs, schizonts) of the fifth human malaria, Plasmodium knowlesi,
resemble those of:
A. Plasmodium malariae
B. Plasmodium ovale
C. Plasmodium falciparum
D. Plasmodium vivax
Plasmodium malariae
Autofluorescence requires no stain and is
recommended for the identification of:
A. Entamoeba histolytica cysts
B. Toxoplasma gondii tachyzoites
C. Dientamoeba fragilis trophozoites
D. Cyclospora cayetanensis oocysts
Cyclospora cayetanensis oocysts
Key characteristics of infection with Plasmodium knowlesi include:
A. Rapid erythrocytic cycle (24 hr), will infect all
ages of RBCs, and can cause serious disease
B. Erythrocytic cycle limited to young RBCs and
causes a relatively benign disease
C. The possibility of a true relapse from the liver, infection in older RBCs, and causes serious disease
D. Extended life cycle (72 hr), will infect all ages
of RBCs, and disease is similar to that caused
by P. ovale
Rapid erythrocytic cycle (24 hr), will infect all
ages of RBCs, and can cause serious disease
Microsporidial infections can be confirmed using:
A. Light microscopy and modified trichrome stains
B. Phase contrast microscopy and routine trichrome stains
C. Electron microscopy and modified acid-fast
stains
D. Fluorescence microscopy and hematoxylin stains
Light microscopy and modified trichrome stains
Although the pathogenicity of Blastocystis
hominis remains controversial, newer information suggests that:
A. Most organisms are misdiagnosed as artifacts
B. Numerous strains/species are included in the name, some of which are pathogenic and some are nonpathogenic
C. The immune status of the host is solely
responsible for symptomatic infections
D. The number of organisms present determines pathogenicity
Numerous strains/species are included in the name, some of which are pathogenic and some are nonpathogenic
Potential problems using EDTA anticoagulant and holding the blood too long prior to preparation of thick and thin blood films include:
A. Changes in parasite morphology, loss of organisms within several hours, and poor staining
B. Loss of Schüffner’s dots, poor adherence of the blood to the glass slide, and parasites beginning the vector cycle within the tube of blood
C. Neither A nor B
D. All of these options
All of these options
Which of the following is a key characteristic of
the thick blood film?
A. The ability to see the parasite within the RBCs
B. The ability to identify the parasites to the
species level
C. The examination of less blood than the thin
blood film
D. The necessity to lake the RBCs during or prior to staining
The necessity to lake the RBCs during or prior to staining
