Assessment PARA Flashcards
ECOFRIENDLY fecal fixative:
Formalin
Schaudinn’s
Polyvinyl alcohol
Merthiolate-iodine-formalin
Polyvinyl alcohol
The formalin–ether (ethyl acetate) concentration procedure for feces is used to demonstrate:
Motility of helminth larvae
Protozoan cysts and helminth eggs
Formation of amoebic pseudopods
Trophozoites
Protozoan cysts and helminth eggs
Layers obtained in the formalin ether sedimentation technique (top to
bottom):
Sediment > formalin > debris > ether
Sediment > debris > formalin > ether
Ether > formalin > debris > sediment
Ether > debris > formalin > sediment
Ether > debris > formalin > sediment
“Cultures of parasites are different from bacterial cultures; no quality control is needed.” This statement is:
True, if two tubes of media are set up for each patient
True, if the media are checked every 24 hours
False, unless two different types of media are used
False, and organism and media controls need to be set up
False, and organism and media controls need to be set up
Duplicate cultures should be set up, and specific American Type Culture Collection (ATCC)
strains should be cultured along with the patient specimens to confirm that the culture
system is operating properly. This approach is somewhat different from that used in
diagnostic bacteriology and mycology
Charcot–Leyden crystals in stool may be associated with an immune
response and are thought to be formed from the breakdown products of:
Neutrophils
Eosinophils
Lymphocytes
Monocytes
Eosinophils
A mother states that she has observed her 4-year-old son scratching his
anal area frequently. The most likely cause of this condition is:
Trichomonas vaginalis
Enterobius vermicularis
Ascaris lumbricoides
Necator americanus
Entamoeba histolytica
Enterobius vermicularis
The term internal autoinfection can be associated with the following parasites:
Cryptosporidium spp. and Giardia lamblia
Cystoisospora belli and Strongyloides stercoralis
Cryptosporidium spp. and Strongyloides stercoralis
Giardia lamblia and Cystoisospora belli
Cryptosporidium spp. and Strongyloides stercoralis
Both Cryptosporidium and S. stercoralis have an internal autoinfection capability in their
life cycles. This means that the cycle and infection can continue even after the patient has
left the endemic area. In the case of Cryptosporidium, the cycle continues in patients who
are immunocompromised and unable to self-cure.
Larva with heart to lung migration, except:
Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura
Trichuris trichiura
Triad of infection or unholy 3, except:
Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura
Strongyloides stercoralis
Visceral larva migrans is associated with which of the following organisms?
Toxocara—serology
Onchocerca—skin snips
Dracunculus—skin biopsy
Angiostrongylus—CSF examination
Toxocara—serology
Ingestion of which of the following eggs will result in infection?
Strongyloides stercoralis
Opisthorchis sinensis
Toxocara canis
Schistosoma japonicum
Toxocara canis
The eggs of T. canis are infectious for humans and cause visceral larva migrans. These ascarid eggs of the dog can infect humans; the eggs hatch and the larvae wander through the deep tissues, occasionally the eye. In this case, the human becomes the accidental
intermediate host.
A helminth egg is described as having terminal polar plugs. The most likely helminth is:
Hookworm
Trichuris trichiura
Fasciola hepatica
Diphyllobothrium latum
Trichuris trichiura
You are working in a rural medical clinic in China and a 3-year- old girl is
brought in by her mother. The child appears emaciated and, upon testing,
is found to have a hemoglobin level of 5 g/dL. Her feet and ankles are
swollen, and there is an extensive rash on her feet, ankles, and knees. The
most likely parasitic infection that causes the child’s condition is:
Schistosomiasis
Cercarial dermatitis
Hookworm infection
Ascariasis
Hookworm infection
May be associated with vertical transmission and congenital infections:
Ascaris lumbricoides
Ancylostoma duodenale
Necator americanus
Enterobius vermicularis
Ancylostoma duodenale
The parasites penetrate the skin and cause cutaneous larva migrans (CLM), also referred to as creeping eruption:
Ancylostoma duodenale and Necator americanus
Ancylostoma braziliense and Ancylostoma caninum
Toxocara cati and Toxocara canis
Brugia malayi and Loa loa
Ancylostoma braziliense and Ancylostoma caninum
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:
Trypanosoma cruzi
Strongyloides stercoralis
Paragonimus westermani
Naegleria fowleri
Strongyloides stercoralis
Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:
Short buccal capsule and large genital primordial
Long buccal capsule and pointed tail
Short buccal capsule and small genital primordium
Small genital primordium and notch in tail
Short buccal capsule and large genital primordial
When the undercooked meat is digested in the stomach, the larvae are resistant to the gastric pH and pass to the intestine, where they invade
the mucosa:
Ascaris
Enterobius
Trichuris
Trichinella
Trichinella
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:
Toxoplasma gondii
Taenia solium
Hymenolepis nana
Trichinella spiralis
Trichinella spiralis
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:
Thin blood films—Leishmania
Urine—concentration for Trichomonas vaginalis
Thick blood films—microfilariae
Thin blood films—Babesia
Thick blood films—microfilariae
The most common identified species of filarial worms that infect
humans:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Wuchereria bancrofti
Which microfilariae are usually not found circulating in the peripheral blood?
Brugia malayi
Wuchereria bancrofti
Onchocerca volvulus
Loa loa
Onchocerca volvulus
Which of the following statements is true regarding onchocerciasis?
The adult worm is present in the blood
The microfilariae are in the blood during the lateevening hours
The diagnostic test of choice is the skin snip
The parasite resides in the deep lymphatics
The diagnostic test of choice is the skin snip
The tail is often referred to as a “shepherd’s crook.”
Brugia malayi
Mansonella perstans
Mansonella streptocerca
Onchocerca volvulus
Mansonella streptocerca
The worm has a characteristic, thick cuticle and a large uterus that fills the body cavity and contains rhabditoid larvae.
Ancylostoma caninum
Dracunculus medinensis
Strongyloides stercoralis
Trichinella spiralis
Dracunculus medinensis
The worms are incapable of maturation within the human host and migrate aimlessly, causing tissue damage and inflammation.
Brugia malayi
Dracunculus medinensis
Gnathostoma spinigerum
Trichinella spiralis
Gnathostoma spinigerum
Which parasite causes eosinophilic meningoencephalitis, a form of larva
migrans causing fever, headache, stiff neck, and increased cells in the spinal fluid?
Necator americanus
Angiostrongylus cantonensis
Strongyloides stercoralis
Ancylostoma braziliense
Angiostrongylus cantonensis
The examination of sputum may be necessary to diagnose infection with:
Paragonimus westermani
Trichinella spiralis
Wuchereria bancrofti
Fasciola hepatica
Paragonimus westermani
Largest of the INTESTINAL trematodes, and infection is acquired by ingestion of raw water chestnuts or caltrop:
Fasciolopsis buski
Fasciola gigantica
Heterophyes heterophyes
Metagonimus yokogawai
Fasciolopsis buski
Eggs are operculated with slight opercular shoulders, yellow-brown, embryonated:
Fasciola hepatica
Heterophyes heterophyes
Paragonimus westermani
Schistosma japonicum
Heterophyes heterophyes
Severe infections may cause obstruction of the biliary ducts, resulting in enlargement and tenderness of the liver, cirrhosis, cholecystitis (inflammation of the gallbladder), and cholangiocarcinoma (cancerous
growth in bile duct epithelium).
C. sinensis and O. viverrini
H. heterophyes and M. yokogawai
P. westermani and P, mexicanus
S. japonicum and S. mansoni
C. sinensis and O. viverrini
A 32-year-old male tourist traveled to Senegal for 1 month. During the trip, he swam in the Gambia river. Two months after his return, he began complaining of intermittent lower abdominal pain with dysuria. Laboratory results of ova and parasites revealed eggs with a terminal spine. Which of the following parasites is the cause of the patient’s symptoms?
Schistosoma mansoni
Schistosoma haematobium
Ascaris lumbricoides
Taenia solium
Schistosoma haematobium
Resembles egg of S. haematobium, but acid-fast positive:
S. japonicum
S. intercalatum
S. mansoni
S. mekongi
S. intercalatum
Schistosoma intercalatum eggs are found in:
Stool
Urine
Both of these
None of these
Stool
S. intercalatum eggs are only found in feces, not in urine specimens
Examination of 24-hour unpreserved urine specimen is sometimes helpful in the recovery of:
Trichomonas vaginalis trophozoites
Schistosoma haematobium eggs
Strongyloides stercoralis larvae
Enterobius vermicularis eggs
Schistosoma haematobium eggs
The miracidial hatching test helps to demonstrate the viability of eggs of:
Taenia species
Schistosoma species
Hookworm species
Opisthorchis species
Schistosoma species
Two helminth eggs that may resemble one another are:
Diphyllobothrium latum and Paragonimus westermani
Opisthorchis sinensis and Fasciolopsis buski
Taenia saginata and Hymenolepis nana
Ascaris lumbricoides and Trichostrongylus
Diphyllobothrium latum and Paragonimus westermani
Eating poorly cooked pork can lead to an infection with:
Taenia solium and Trichinella spiralis
Taenia saginata and Hymenolepis nana
Trichuris trichiura and Hymenolepis diminuta
Diphyllobothrium latum and Ascaris lumbricoides
Taenia solium and Trichinella spiralis
Several Papua New Guinea villagers known to eat pork during celebrations were reported to be suffering from an outbreak of epileptiform seizures. One of the first things you should investigate is:
The prevalence of Ascaris infections in the population
The prevalence of schistosomiasis in the population
The presence of Trypanosoma brucei gambiense in the villagers
The presence of Giardia cysts in the drinking water
The presence of Taenia solium in the pigs
The presence of Taenia solium in the pigs
An operculated cestode egg that can be recovered from human feces is:
Clonorchis sinensis
Diphyllobothrium latum
Paragonimus westermani
Dipylidium caninum
Diphyllobothrium latum
D. latum is the only operculated cestode egg that is found in humans; the infection is acquired from the ingestion of raw freshwater fish.
Humans acquire infections with Diphyllobothrium latum adult worms by:
Ingestion of freshwater crabs
Skin penetration of cercariae
Ingestion of water chestnuts
Ingestion of raw freshwater fish
Ingestion of raw freshwater fish
In infections with Taenia solium, humans can serve as the:
Definitive host
Intermediate host
Either the definitive or the intermediate host
None of these options
Either the definitive or the intermediate host
If humans ingest T. solium cysticerci in uncooked or rare pork, the adult tapeworm will mature within the intestine (human will serve as definitive host); if eggs from the adult
tapeworm are ingested, then the cysticerci will develop in human tissues (accidental intermediate host), causing cysticercosis.
In a condition resulting from the accidental ingestion of eggs, the human
becomes the intermediate rather than the definitive host. The correct answer is:
Trichinosis
Strongyloidiasis
Ascariasis
Cysticercosis
Cysticercosis
Humans can serve as both the intermediate and definitive host in infections caused by:
Enterobius vermicularis
Hymenolepis nana
Schistosoma japonicum
Ascaris lumbricoides
Hymenolepis nana
Infection is more frequent in populations living in conditions of poverty or poor hygiene, in day care centers, and in persons living in institutional
settings or prisons.
D. latum
D. caninum
H. nana
T. saginata
H. nana
The eggs (70 to 85 μm by 60 to 80 μm) are large, ovoid, yellowish, and moderately thick-shelled. The eggs contain a six-hooked oncosphere with
the absence of polar filaments in the space between the oncosphere and the eggshell.
H. diminuta
H. nana
Both of these
None of these
H. diminuta
Eggs are small and have polar filaments present in the space between the oncospheres and the eggshell.
H. diminuta
H. nana
Both of these
None of these
H. nana
The adult tapeworm of Echinococcus granulosus is found in the intestine of:
Dogs
Sheep
Humans
Cattle
Dogs
Although the hydatid cysts are found in sheep or in humans (accidental intermediate host),
the adult tapeworms of E. granulosus are found in the intestine of the dog.
Surgery is the most common form of treatment for hydatid disease. The
procedure involves surgical removal of cysts or inactivation of hydatid
sand by injecting the cyst with __________ and then removing it.
10% formalin
Hydrogen peroxide
Methanol
Acetone
10% formalin
Surgery is the most common form of treatment for hydatid disease. The procedure
involves surgical removal of cysts or INACTIVATION OF HYDATID SAND by injecting the
cyst with 10% FORMALIN and then removing it.
If surgical removal is not feasible:
PAIR (PUNCTURE, ASPIRATION, INFECTION, AND REINJECTION)
Used for the inactivation of hydatid sand by injecting the cyst with a CYSTICIDAL AGENT
HYPERTONIC 30% SALINE
*0.5% CETRIMIDE
*70 TO 95% ETHANOL
Most lethal of all helminthic diseases:
Taenia saginata
Taenia solium
Echinococcus granulosus
Echinococcus multilocularis
Echinococcus multilocularis
Tapeworm that causes coenurosis in humans:
Echinococcus multilocularis
Spirometra mansonoides
Taenia multiceps
Taenia solium
Taenia multiceps
An Entamoeba histolytica trophozoite has the following characteristics:
-Central karyosome in the nucleus, ingested RBCs, and clear pseudopodia
-Ingested RBCs, clear pseudopodia, and uneven chromatin on the nuclear membrane
-Ingested RBCs, clear pseudopodia, and large glycogen vacuoles in cytoplasm
-Large, blotlike karyosome, ingested white blood cells (WBCs), and granular pseudopods
Central karyosome in the nucleus, ingested RBCs, and clear pseudopodia
A patient has been diagnosed as having amebiasis but continues to be asymptomatic. The physician has asked for an explanation and recommendations regarding follow-up. Suggestions should include:
Consideration of Entamoeba histolytica versus Entamoeba dispar
A request for an additional three stools for culture
Initiating therapy, regardless of the patient’s asymptomatic status
Performance of barium x-ray studies
Consideration of Entamoeba histolytica versus Entamoeba dispar
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:
Trichomonas tenax
Entamoeba histolytica/E. dispar
Entamoeba polecki
Entamoeba gingivalis
Entamoeba gingivalis
If the granules are on one side, the nucleus may appear to have a “basket nucleus” arrangement of chromatin, more commonly seen in the cyst
stage.
D. fragilis
E. gingivalis
E. nana
I. butschlii
I. butschlii
Cysts of Iodamoeba bütschlii typically have:
Chromatoidal bars with rounded ends
A heavily vacuolated cytoplasm
A large glycogen vacuole
Many ingested bacteria and yeast cells
A large glycogen vacuole
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:
Iodamoeba bütschlii trophozoites
Dientamoeba fragilis trophozoites
Naegleria fowleri trophozoites
Endolimax nana trophozoites
Naegleria fowleri trophozoites
Which of the following causes granulomatous amebic encephalitis (GAE), primarily in immunosuppressed, chronically ill, or otherwise debilitated individuals?
Acanthamoeba
Dientamoeba
Iodamoeba
Naegleria
Acanthamoeba
Eye infections with Acanthamoeba spp. have most commonly been
traced to:
Use of soft contact lenses
Use of hard contact lenses
Use of contaminated lens care solutions
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.
The trichrome staining method
The use of monoclonal reagents for the detection of antibody
The use of non-nutrient agar cultures seeded with Escherichia coli
The Giemsa’s stain method
The use of non-nutrient agar cultures seeded with Escherichia coli
Which of the following is the best technique to identify Dientamoeba fragilis in stool?
Formalin concentrate
Trichrome-stained smear
Modified acid-fast–stained smear
Giemsa’s stain
Trichrome-stained smear
Trophozoites are teardrop shaped and have been described as “someone looking at you”
C. mesnili
D. fragilis
G. lamblia
T. vaginalis
G. lamblia
The organism is found most commonly in the CRYPTS IN THE
DUODENUM:
Cryptosporidium
Isospora spp.
Giardia lamblia
Entamoeba histolytica
Giardia lamblia
Infection mimics acute viral enteritis, bacillary dysentery, bacterial or other food poisonings, acute intestinal amebiasis, or “traveler’s diarrhea”
C. mesnili
D. fragilis
E. hartmanni
G. lamblia
G. lamblia
One of the following protozoan organisms has been implicated in waterborne and foodborne outbreaks. The suspect organism is:
Pentatrichomonas hominis
Giardia lamblia
Balantidium coli
Dientamoeba fragilis
Giardia lamblia
Organisms that should be considered in a waterborne outbreak of diarrheal disease include:
Giardia lamblia and Cryptosporidium spp.
Endolimax nana and Entamoeba histolytica
Blastocystis hominis and Trichomonas vaginalis
Toxoplasma gondii and Schistosoma mansoni
Giardia lamblia and Cryptosporidium spp.
Organisms that should be considered in a nursery school outbreak of diarrhea include:
-Endolimax nana, Giardia lamblia, and Entamoeba coli
-Giardia lamblia, Dientamoeba fragilis, and Cryptosporidium spp.
-Cryptosporidium spp., Trichomonas vaginalis, and Entamoeba coli
-Pentatrichomonas hominis, Dientamoeba fragilis, and Endolimax nana
Giardia lamblia, Dientamoeba fragilis, and Cryptosporidium spp.
G. lamblia, D. fragilis, and Cryptosporidium have been implicated in nursery school outbreaks. Among the many protozoa and coccidia found in the human, these three
organisms have become the most likely parasites in this type of setting.
Fecal immunoassays have become more commonly used to diagnose infections with:
-Endolimax nana and Blastocystis hominis
-Giardia lamblia and Cryptosporidium spp.
-Ascaris lumbricoides and Trichuris trichiura
-Strongyloides stercoralis and Trichomonas vaginalis
Giardia lamblia and Cryptosporidium spp.
Rapid fecal immunoassays have become more widely used for the diagnosis of infections with G. lamblia and Cryptosporidium. For these two organisms, the fecal immunoassays are more sensitive than the routine O&P examination.
Cysts have a single nucleus and a typical curved cytostomal fibril, called the shepherd’s crook:
C. mesnili
D. fragilis
G. lamblia
I. butschlii
C. mesnili
The life cycle and mode of transmission of this protozoan are not known, although transmission in helminth eggs (e.g., Ascaris and Enterobius
spp.) has been postulated:
C. mesnili
D. fragilis
G. lamblia
I. butschlii
D. fragilis
Parasitic organisms that are most often transmitted sexually include:
Entamoeba gingivalis
Dientamoeba fragilis
Trichomonas vaginalis
Diphyllobothrium latum
Trichomonas vaginalis
Which specimen is the LEAST likely to provide recovery of Trichomonas vaginalis?
Urine
Urethral discharge
Vaginal discharge
Feces
Feces
A sexually active 24-year-old woman complains of vaginal itching and vaginal discharge. To verify your tentative diagnosis of trichomoniasis,
you should include which of the following in your workup?
Specific serologic test
Ova and parasite fecal smear
Wet mount of vaginal fluid
Enzyme-linked immunoassay (ELISA) test of serum
Stool culture
Wet mount of vaginal fluid
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:
Leishmaniasis with Leishmania donovani
Leishmaniasis with Leishmania braziliense
Trypanosomiasis with Trypanosoma gambiense
Trypanosomiasis with Trypanosoma cruzi
Trypanosomiasis with Trypanosoma cruzi
T. cruzi, the cause of Chagas disease, has two forms within the human: the trypomastigote
in the blood and the amastigote in the striated muscle (usually cardiac muscle and
intestinal tract muscle).
When malaria smears are requested, what patient information should be obtained?
Diet, age, sex
Age, antimalarial medication, sex
Travel history, antimalarial medication, date of return to United States
Fever patterns, travel history, diet
Travel history, antimalarial medication, date of return to United States
Massive hemolysis, blackwater fever, and central nervous system
involvement are most common with:
Plasmodium vivax
Plasmodium falciparum
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
An apparently fatigued but alert 38-year-old woman has spent 6 months
as a teacher in a rural Thailand village school. Her chief complaints include frequent headaches, occasional nausea and vomiting, andperiodic fever. You suspect malaria and indeed find parasites in red blood cells in a thin blood smear. To rule out the dangerous falciparum form of
malaria, which one of the following choices is NOT consistent with a diagnosis of Plasmodium falciparum malaria based on a microscopic
examination of the blood smear?
Red blood cells containing trophozoites with Schuffner’s dots
Red blood cells containing >1 parasite per RBC
Banana-shaped or crescent-shaped gametocytes
Parasites within normal-sized red blood cells
Parasites with double nuclei
Red blood cells containing trophozoites with Schuffner’s dots
Plasmodium vivax and Plasmodium ovale are similar because they:
Exhibit Schüffner’s dots and have a true relapse in the life cycle
Commonly have appliqué forms in the red cells
Have true stippling, do not have a relapse stage, and infect old red cells
Have no malarial pigment and multiple rings
Exhibit Schüffner’s dots and have a true relapse in the life cycle
Key characteristics of infection with Plasmodium knowlesi include:
Rapid erythrocytic cycle (24 hr), will infect all ages of RBCs, and can cause serious disease
Erythrocytic cycle limited to young RBCs and causes a relatively benign disease
The possibility of a true relapse from the liver, infection in older RBCs, and causes serious disease
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
Key characteristics of an infection with Plasmodium knowlesi include a rapid life cycle (24 hr), the potential to infect all ages of RBCs, and the possibility of serious symptoms similar
to those seen with P. falciparum infections. There is no relapse from the liver with this species
Early ring stages of the fifth human malaria, Plasmodium knowlesi, resemble those of:
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
Plasmodium vivax
Plasmodium falciparum
Older developing stages (trophs, schizonts) of the fifth human malaria, Plasmodium knowlesi, resemble those of:
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
Plasmodium vivax
Plasmodium malariae
A patient is being seen in the emergency department for a low-grade
fever, headache, and general malaise after returning from Africa on a
photographic safari. The physician has requested blood for malaria; the
laboratory would like to have patient information regarding:
Specific travel history and body temperature every 4 hours
Liver function tests and prophylactic medication history
Transfusion history and body temperature every 4 hours
Prophylactic medication history and specific travel history
Prophylactic medication history and specific travel history
If the patient has malaria and has been taking prophylaxis (often sporadically), the number
of parasites on the blood smear will be reduced and examination of routine thick and thin
blood films should be more exhaustive. Also specific geographic travel history may help to
determine whether chloroquine-resistant Plasmodium falciparum may be a factor.
Recommended stain for all parasitic blood works:
Giemsa
Wright
Modified acid fast stain
Modified trichrome stain
Giemsa
There are few procedures considered STAT in parasitology. The most obvious situation would be:
Ova and parasite examination for giardiasis
Baermann’s concentration for strongyloidiasis
Culture of amoebic keratitis
Blood films for malaria
Blood films for malaria
Babesia has been implicated in disease from both splenectomized and nonsplenectomized patients. Morphologically, the parasites resemble:
Plasmodium falciparum rings
Leishmania donovani amastigotes
Microsporidial spores
Trypanosoma cruzi trypomastigotes
Plasmodium falciparum rings
Oocysts survive in the environment for several months to more than 1 year and are resistant to disinfectants, freezing, and drying. However, they
are killed by heating to 70°C for 10 minutes.
Balamuthia mandrillaris
Pentatrichomonas hominis
Isospora belli
Toxoplasma gondii
Toxoplasma gondii
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:
The staining time is much longer with regular AFB acid-fast stains
The decolorizer is weaker than acid alcohol used for AFB decolorizing
A counterstain must be used for the modified methods
The stain is more concentrated when staining for AFB
The decolorizer is weaker than acid alcohol used for AFB decolorizing
Patients with severe diarrhea should use “enteric precautions” to prevent nosocomial infections with:
Giardia lamblia
Ascaris lumbricoides
Cystoisospora belli
Cryptosporidium spp.
Cryptosporidium spp.
Cryptosporidium oocysts (unlike those of C. belli) are immediately infective when passed
in stool, and nosocomial infections have been well documented with this coccidian.
Parasite stages that are immediately infective for humans on passage from the gastrointestinal tract include:
Schistosoma spp. eggs
Toxoplasma gondii bradyzoites
Giardia lamblia trophozoites
Cryptosporidium spp. oocysts
Cryptosporidium spp. oocysts
Cryptosporidium spp. oocysts are immediately infectious when passed in the stool,
regardless of the stool consistency (formed—liquid).
In an outbreak of diarrheal disease traced to a municipal water supply, the most likely causative agent is:
Cryptosporidium spp.
Cystoisospora belli
Entamoeba histolytica
Dientamoeba fragilis
Cryptosporidium spp.
Cryptosporidium oocysts have been transmitted through contaminated municipal water
supplies. Such outbreaks have been well documented.
Oocysts of Cryptosporidium spp. can be detected in stool specimens using:
Modified Ziehl–Neelsen acid-fast stain
Gram stain
Methenamine silver stain
Trichrome stain
Modified Ziehl–Neelsen acid-fast stain
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:
Dientamoeba fragilis
Cystoisospora belli
Cyclospora cayetanensis
Schistosoma mansoni
Cyclospora cayetanensis
Examination of a modified acid-fast stained fecal smear reveals round structures measuring approximately 8–10 μm, some of which are stained and some of which are not. They do not appear to show any internal
morphology. The patient is symptomatic with diarrhea, and the cause may be:
Blastocystis hominis
Polymorphonuclear leukocytes
Large yeast cells
Cyclospora cayetanensis
Cyclospora cayetanensis
One of the newer coccidian parasites, C. cayetanensis, has been implicated in cases of
human diarrhea. The recommended stains are modified acid-fast stains, and the
organisms are quite variable in their staining characteristics. The oocysts are immature
when passed (no internal morphology) and they measure about 8–10 μm.
Autofluorescence requires no stain and is recommended for the identification of:
Entamoeba histolytica cysts
Toxoplasma gondii tachyzoites
Dientamoeba fragilis trophozoites
Cyclospora cayetanensis oocysts
Cyclospora cayetanensis oocysts
Primary infections with the microsporidia may originate in:
The lung
The nervous system
The gastrointestinal tract
Mucocutaneous lesions
The gastrointestinal tract
The microsporidia are protozoans (now classified with the fungi) that have been implicated in human disease primarily in
Immunocompromised patients
Pediatric patients under the age of 5 years
Adult patients with congenital immunodeficiencies
Patients who have been traveling in the tropics
Immunocompromised patients
A transplant patient on immunosuppressive drugs developed increasing diarrhea. The most likely combination of disease and diagnostic
procedure is:
Trichinosis and trichrome stain
Microsporidiosis and modified trichrome stain
Paragonimiasis and wet preparation
Toxoplasmosis and Gram stain
Microsporidiosis and modified trichrome stain
Microsporidia have been identified as causing severe diarrhea, disseminated disease in other body sites, and ocular infections. Routes
of infection have been identified as:
Ingestion
Inhalation
Direct contamination from the environment
Ingestion, inhalation, and direct contamination
Ingestion, inhalation, and direct contamination
Confirmation of an infection with microsporidia can be achieved by seeing:
The oocyst wall
Sporozoites within the spore
Evidence of the polar tubule
Organisms stained with modified acid-fast stains
Evidence of the polar tubule
Confirmation of an infection with microsporidial spores can be achieved by seeing
evidence of the polar tubule within the spores (horizontal or diagonal line across/within
the spore).
Microsporidial infections can be confirmed using:
Light microscopy and modified trichrome stains
Phase contrast microscopy and routine trichrome stains
Electron microscopy and modified acid-fast stains
Fluorescence microscopy and hematoxylin stains
Light microscopy and modified trichrome stains
An infection with microsporidia can be confirmed using modified trichrome stains (10X the normal dye content found in routine trichrome stains) and light microscopy. The internal
polar tubule will be visible within some of the spores; this will serve as confirmation of the
infection.
All of the following are sexually transmitted protozoans except:
Trichomonas vaginalis
Entamoeba histolytica
Giardia lamblia
Cryptosporidium spp.
Balantidium coli
Balantidium coli
The World Health Organization has ranked trichomoniasis as the most prevalent, nonviral, sexually transmitted disease in the world with an estimated 172 million new cases a year.
The intestinal protozoa Giardia lamblia, Entamoeba histolytica, and Cryptosporidium spp. are significant causes of STDs, especially among homosexual populations
Which of the following is associated with LOEFFLER’S SYNDROME:
Ascaris lumbricoides
Enterobius vermicularis
Trichuris trichiura
Wuchereria bancrofti
Ascaris lumbricoides
LOEFFLER’S SYNDROME: transient pulmonary infiltration; day-to-day clearing in 3 to 14 days; associated with marked peripheral eosinophilia
VISCERAL LARVA MIGRANS (VLM) and OCULAR LARVA MIGRANS (OLM) are caused by accidental ingestion of eggs of:
Ancylostoma braziliense, Ancylostoma caninum
Toxocara cati, Tocara canis
Toxocara cati, Tocara canis
A serum titer of 1: 8 is considered significant for OLM; 1: 32 is significant for VLM.
CREEPING ERUPTION or CUTANEOUS LARVA MIGRANS (CLM) is caused by skin penetration of infective larvae of:
Ancylostoma braziliense, Ancylostoma caninum
Toxocara cati, Tocara canis
Ancylostoma braziliense, Ancylostoma caninum
A patient presents with vague abdominal pains and a MICROCYTIC HYPOCHROMIC anemia. A possible causative parasite is:
Enterobius vermicularis
Ancylostoma duodenale
Brugia malayi
Trichinella spiralis
Ancylostoma duodenale
Infective stage is the SHEATHED FILARIFORM LARVA:
Strongyloides stercoralis
Ancylostoma duodenale, Necator americanus
Ancylostoma duodenale, Necator americanus
Infective stage is the UNSHEATHED FILARIFORM LARVA:
Strongyloides stercoralis
Ancylostoma duodenale, Necator americanus
Strongyloides stercoralis
Which of the following roundworms is capable of AUTOINFECTION, HYPERINFECTION, and a HEAVY WORM BURDEN with characteristic larval migration required in the life cycle?
Ancylostoma duodenale
Enterobius vermicularis
Strongyloides stercoralis
Ascaris lumbricoides
Strongyloides stercoralis
Parasite recovery from stool may be enhanced by the BAERMANN FUNNEL TECHNIQUE:
Ascaris lumbricoides
Enterobius vermicularis
Strongyloides stercoaralis
Ancylostoma duodenale
Strongyloides stercoaralis
The basic method is to wrap the sample in a PAPER TISSUE OR CLOTH AND SUBMERGE IT IN A FUNNEL FILLED WITH WATER. The nematodes will clump and sink to the bottom of the funnel where they can be recovered.
A primate parasite, has been isolated from humans in Africa and causes a severe life-threatening condition called “SWOLLEN BELLY SYNDROME.”
Toxocara cati
Toxocara canis
Ancylostoma caninum
Strongyloides fuelleborni
Strongyloides fuelleborni
The intestinal nematode considered capable of VERTICAL TRANSMISSION and the potential cause for CONGENITAL INFECTIONS is:
Ascaris lumbricoides
Enterobius vermicularis
Trichuris trichiura
Ancylostoma duodenale
Ancylostoma duodenale
The filariform larva is the infective stage for:
Ascaris lumbricoides, Trichostrongylus spp.
Ascaris lumbricoides, Strongyloides stercoralis
Ancylostoma duodenale, Strongyloides stercoralis
Trichuris trichiura, Necator americanus
Ancylostoma duodenale, Strongyloides stercoralis
The examination of blood film should be performed at _____ to DETECT MICROFILARIAE.
LPO
HPO
OIO
LPO
MICROFILARIA: LPO
PLASMODIA, TRYPANOSOMES: OIO
MOST COMMON identified species of filarial worms that infect humans:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Wuchereria bancrofti
Lymphatic vessel involvement within the RETROPERITONEAL REGION is associated with:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Wuchereria bancrofti
The nematode Loa loa is transmitted to humans by:
Culex spp.
Simulium spp.
Mansonia spp.
Chrysops spp.
Chrysops spp.
The parasite is transmitted by the black fly, Simulium spp.
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Onchocerca volvulus
Sheathed microfilaria, nuclei extend to the tail in an irregularly arranged fashion:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Loa loa
W. bancrofti: Sheathed, tail free of nuclei
B. malayi: Sheathed, tail with 2 separate nuclei
L. loa: Sheathed, nuclei up to the tip of the tail
O. volvulus: Unsheathed, tail is free of nuclei
M. perstans: Unsheathed, nuclei up to the tip of the tail
M. ozzardi: Unsheathed, tail is free of nuclei
M. streptocerca: Shepherd’s crook
Microfilariae are sheathed and contain 4 to 5 subterminal and 2 TERMINAL NUCLEI in the tail:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Brugia malayi
W. bancrofti: Sheathed, tail free of nuclei
B. malayi: Sheathed, tail with 2 separate nuclei
L. loa: Sheathed, nuclei up to the tip of the tail
O. volvulus: Unsheathed, tail is free of nuclei
M. perstans: Unsheathed, nuclei up to the tip of the tail
M. ozzardi: Unsheathed, tail is free of nuclei
M. streptocerca: Shepherd’s crook
Unsheathed microfilaria, tail is free of nuclei:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Onchocerca volvulus
W. bancrofti: Sheathed, tail free of nuclei
B. malayi: Sheathed, tail with 2 separate nuclei
L. loa: Sheathed, nuclei up to the tip of the tail
O. volvulus: Unsheathed, tail is free of nuclei
M. perstans: Unsheathed, nuclei up to the tip of the tail
M. ozzardi: Unsheathed, tail is free of nuclei
M. streptocerca: Shepherd’s crook
The tail of this microfilaria is often referred to as a “shepherd’s crook”:
Mansonella perstans
Mansonella ozzardi
Mansonella streptocerca
Wucheriria bancrofti
Mansonella streptocerca
The endosymbiont Wolbachia sp. is required for parasite reproduction in all of the following except:
Onchocerca volvulus
Brugia timori
Loa loa
Wuchereria bancrofti
Loa loa
W. bancrofti, Brugia spp., and Onchocerca volvulus harbor an endosymbiotic alpha-proteobacterium, Wolbachia sp. Wolbachia is an obligate intracellular organism.
The worm has a characteristic, thick cuticle and a large uterus that fills the body cavity and contains rhabditoid larvae:
Ascaris lumbricoides
Enterobius vermicularis
Ancylostoma duodenale
Dracunculus medinensis
Dracunculus medinensis
Removal and gradual retraction of the adult gravid female worm is recommended in infections with:
Ancylostoma braziliense
Dracunculus medinensis
Trichinella spiralis
Toxocara cati
Dracunculus medinensis
The following infection may RESEMBLE ACUTE APPENDICITIS:
Parastrongylus costaricensis
Gnathostoma sp.
Toxocara cati
Parastrongylus caninum
Parastrongylus costaricensis
Infection with Clonorchis or Opisthorchis may result from eating raw or undercooked:
Aquatic vegetation
Crabs
Crayfish
Freshwater fish
Freshwater fish
Which of the following can be acquired by ingestion of crab or crayfish bearing the metacercaria:
Fasciola hepatica
Fasciolopsis buski
Clonorchis sinensis
Paragonimus westermani
Paragonimus westermani
The eggs are small, yellow-brown, EMBRYONATED, and operculated and may have MINIMAL OPERCULAR SHOULDERS:
Fasciola hepatica
Fasciolopsis buski
Heterophyes heterophyes
Paragonimus westermani
Heterophyes heterophyes
EMBRYONATED (MATURE) EGGS
“CHOS/SHOC” OPERCULATED:
Clonorchis, Heterophyes, Opistorchis
MATURE, NONOPERCULATED: Schistosoma
UNEMBROYONATED (IMMATURE) EGGS, OPERCULATED
Fasciola, Fasciolopsis, Echinostoma
UNEMBRYONATED, WITH OPERCULUM AND ABORPERCULUM:
Paragonimus
The infective life cycle stage of a fluke (except blood fluke) is the:
Miracidium
Cercariae
Metacercariae
Pleurocercariae
Metacercariae
The fluke acquired by eating contaminated vegetation is:
Clonorchis sinensis
Fasciolopsis buski
Heterophyes heterophyes
Paragonimus westermani
Fasciolopsis buski
Fish carrying metacercariae may transmit:
Clonorchis sinensis
Fasciolopsis buski
Paragonimus westermani
Schistosoma haematobium
Clonorchis sinensis
Paragonimus westermani infection is acquired by:
Drinking contaminated water
Eating infected crustacea
Eating infected fish
Eating infected water chestnuts
Eating infected crustacea
The mode of transmission of schistosomal infection is by:
Ingestion of contaminated aquatic vegetation
Direct penetration of the skin by cercariae
Ingestion of raw fish
Mosquito bite
Direct penetration of the skin by cercariae
The drug of choice for treatment of schistosome infections is:
Metrifonate
Praziquantel
Bilarcil
Niclosamide
Praziquantel
Infection with S. mansoni may require a larger dose than that for the other species.
A diagnostic characteristic of the egg of Schistosoma mansoni is:
A large lateral spine
No spine
A pointed terminal spine
A small lateral spine
A large lateral spine
To optimize recovery of S. haematobium in urine, the specimen should be collected:
Early morning
Between noon and 2 pm
Between 2 pm and 4 pm
Between 10 pm and 2 am
Between noon and 2 pm
Infection with S. haematobium may present with which of the following?
Nausea
Basophilia
Hematuria
Jaundice
Hematuria
A patient from the Great Lakes area presents with vague abdominal symptoms and a MACROCYTIC ANEMIA. Which cestode would be the probable cause?
Diphyllobothrium latum
Echinococcus granulosus
Taenia saginata
Hymenolepis nana
Diphyllobothrium latum
In the Diphyllobothrium latum life cycle, the infective stage for humans is:
Cysticercus
Cysticercoid
Procercoid
Plerocercoid
Plerocercoid
Only cestode to have an aquatic life cycle:
Diphyllobothrium latum
Dipylidium caninum
Hymenolepis diminuta
Hymenolepis nana
Diphyllobothrium latum
1st intermediate host: COPEPOD
2nd intermediate host, reservoir host: FISH
Definitive host: MAN
Lifespan of D. latum, T. saginata and T. solium:
Usually less than 1 year
1 to 5 years
10 to 15 years
Up to 25 years
Up to 25 years
H. nana: Perhaps many years as a result of autoinfection
H. diminuta: Usually less than 1 year
D. caninum: Usually less than 1 year
D. latum, Taenia: Up to 25 years
Thick-walled POLLEN GRAINS resemble the eggs of:
Ascaris lumbricoides
Dipylidium caninum
Hymenolepis nana
Taenia species
Taenia species
Which of the following can bypass the need for an intermediate host?
Diphyllobothrium latum
Dipylidium caninum
Hymenolepis diminuta
Hymenolepis nana
Hymenolepis nana
Which tapeworm infects CATTLE as an INTERMEDIATE HOST?
Taenia saginata
Dipylidium caninum
Hymenolepis diminuta
Hymenolepis nana
Taenia saginata
Definitive host of Taenia saginata:
Cow
Pig
Insect
Human
Human
Human serves as the definitive host for beef (Taenia saginata) and pork (Taenia solium) tapeworms; cows/ camels and pigs serve as intermediate hosts, respectively. Humans also serve as the intermediate host for T. solium (cysticercosis).
Which tapeworm cannot be identified to the species level based on its egg morphology; instead, proglottids must be examined?
Diphyllobothrium
Dipylidium
Hymenolepis
Taenia
Taenia
Uterine branches visualized by staining the proglottids with INDIA INK
T. SAGINATA: 15 to 20 branches, dichotomous or tree-like
T. SOLIUM: 7 to 13 lateral branches, dendritic or fingerlike
Gravid proglottids resemble rice grains(dry) or cucumber seeds (moist):
Diphyllobothrium latum
Dipylidium caninum
Taenia spp.
Hymenolepis nana
Dipylidium caninum
Eggs HAVE POLAR FILAMENTS present in the space between the oncospheres and the eggshell:
Hymenolepis diminuta
Hymenolepis nana
Hymenolepis nana
The eggs contain a six-hooked oncosphere with the ABSENCE OF POLAR FILAMENTS in the space between the oncosphere and the eggshell:
Hymenolepis diminuta
Hymenolepis nana
Hymenolepis diminuta
Protozoan with large karyosome, may be surrounded by refractile granules that are difficult to see (“BASKET NUCLEUS”):
Endolimax nana
Entamoeba coli
Entamoeba histolytica
Iodamoeba butschlii
Iodamoeba butschlii
Which operculated ovum contain a miracidium and can appear in sputum, often accompanied by blood and Charcot-Leyden crystals?
Fasciola hepatica
Paragonimus westermani
Schistosoma mansoni
Dipylidium caninum
Paragonimus westermani
Which of the following is the first intermediate host of the flukes?
Snail
Water plant
Fish
Crab
Snail
What is a schistosomule?
Cercaria
Cercaria minus tail
Free-swimming cercaria
Metacercaria
Cercaria minus tail
Which tapeworm proglottid makes its way across the fecal specimen by doubling movements, and is seen under the microscope to have numerous regular uterine branches (more than 15) resembling those of a tree?
Taenia saginata
Taenia solium
Diphyllobothrium lactum
Dipylidium caninum
Taenia saginata
Which species of Taenia has 7 to 12 uterine branches?
Taenia solium
Taenia saginata
Echinococcus granulosus
None of the above
Taenia solium
The eggs of Echinococcus granulosus are found in the feces of:
Cats
Fish
Dog
Cattle
Dog
Which of the following is found in the intermediate host of Echinococcus granulosus?
Adult worm
Egg
Hydatid cyst
Pseudocyst
Hydatid cyst
The first intermediate host of Diphyllobothrium latum:
Copepod
Snail
Fish
Crab
Copepod
The second intermediate host of Diphyllobothrium latum
Cattle
Waterplants
Crayfish
Freshwater fish
Freshwater fish
What is the infective stage of the broad fish tapeworms to human?
Plerocercoid
Coracidium
Hydatid cyst
Cysticerus
Plerocercoid
In some individuals, particularly those of Scandinavian extraction, this worm can case a megaloblastic anemia:
Diphyllobothrium latum
Dipylidium caninum
Taenia solium
Necator americanus
Diphyllobothrium latum
Which of the following worms have separate sexes?
Intestinal flukes
Liver flukes
Tapeworms
Blood flukes
Blood flukes
The male roundworm is differentiated from the female roundworm by its:
Dorsally curved posterior
Pointed posterior
Square posterior
Rounded posterior
Dorsally curved posterior
Which stage of Trichuris trichiura is infective to humans?
Rhabditiform larva
Filariform larva
Cyst
Embryonated egg
Embryonated egg
Trichuris trichiura, hookworm, and _______ ”unholy three” of roundworm.
Enterobius vermicularis
Ascaris lumbricoides
Taenia saginata
Hymenolepsis nana
Ascaris lumbricoides
The helminth that induces a hypochromic microcytic anemia in its host is the:
Hookworm
Whipworm
Pinworm
Threadworm
Hookworm
The rhabditiform larva of the hookworm has a:
Long buccal cavity equal to the width of the body
Short buccal cavity equal to ½ the width of the body
Medium length buccal cavity
Has no buccal cavity
Long buccal cavity equal to the width of the body
Which of the following larval worms enters the host by penetration of the skin?
Strongloides stercoralis
Ancylostoma duodenale
Both of these
None of these
Both of these
A roundworm that inhabits the small intestine and usually is demonstrated as rhabditiform larvae in the fecal specimen is the:
Hookworm
Large roundworm
Whipworm
Threadworm
Threadworm
Adults of filarial worms live in:
Blood and feces
Urine and lymphatics
Subcutaneous tissues
Lymphatics and subcutaneous tissues
Lymphatics and subcutaneous tissues
Dirofilaria immitis:
Dog heartworm
Dog hookworm
Rat lungworm
Cercarial dermatitis
Dog heartworm
Cutaneous larva migrans or creeping eruptions is caused by:
Larvae of pinworm
Microfilariae
Filariform larvae of the dog hookworm
Metacercariae
Filariform larvae of the dog hookworm
Specific gravity of zinc sulfate solution for the flotation method:
1.01
1.04
1.18
1.48
1.18
The ideal temperature at which to hold a fecal specimen for more than 1 hour is:
Freezer temperature
Refrigerator temperature
Room temperature
Incubator temperature
Refrigerator temperature
Most tapeworms are intestinal parasites of humans. Humans can be both the intermediate and the definitive host of:
Taenia saginata
Taenia solium
Echinococcus granulosus
Diphyllobothrium latum
Taenia solium
Charcot-Leyden crystals in stool may be associated with an immune response and are thought to be the breakdown products of:
Neutrophils
Eosinophils
Monocytes
Lymphocytes
Eosinophils
Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:
Short buccal capsule and large genital primordium
Long buccal capsule and pointed tail
Short buccal capsule and small genital primordium
Small genital primordium and notch in tail
Short buccal capsule and large genital primordium
A mother brings two male children; ages 3 and 4, to the clinic because they are restless, haven’t been sleeping well, and frequently are scratching their bottoms. Examination is consistent with perianal pruritus. What is the most likely etiologic agent involved in this infection?
Enterobius vermicularis
Stronyloides stercoralis
Acanthamoeba duodenale
Necator americanus
Enterobius vermicularis
A 33-year-old dog owner presents with abdominal pain and signs of internal hemorrhaging. Blood tests show eosinophilia, but parasite eggs are NOT found in fecal smears. An ELISA test confirms a diagnosis of visceral larva migrans. What is the most likely etiologic agent involved in this infection?
Schistosoma mansoni
Taenia saginata
Toxocara canis
Dipylidium caninum
Toxocara canis
All of the following larva migrate through the lungs except one:
Ascaris
Hookworm
Pinworm
Stronyloides
Pinworm
Habitat of the adult Trichinella spiralis:
Small intestines
Skeletal muscles
Blood
CSF
Small intestines
T. SPIRALIS ADULT - SMALL INTESTINES
T. SPIRALIS LARVA - MUSCLES
Malabsorption syndrome is associated with this parasite:
Enterobius vermicularis
Necator americanus
Trichuris trichiura
Capillaria philippinensis
Capillaria philippinensis
The mouth of Necator americanus is characterized by the presence of:
Teeth
Cutting plates
Both of these
None of these
Cutting plates
Which of the following microfilariae is unsheathed?
Wuchereria bancrofti
Onchocerca volvulus
Loa loa
Brugia malayi
Onchocerca volvulus
Eye worm producing fugitive swelling or Calabar swelling:
Loa loa
Onchocerca volvulus
Dipetalonema perstans
Mansonella ozzardi
Loa loa
Infective stage of the Schistosomes to their final host:
Miracidium
Sporocyst
Cercaria
Metacercaria
Cercaria
Eggs of this fluke are small and shaped like an old-fashioned electric light bulb:
Clonorchis sinensis
Fasciola lanceolata
Fasciolopsis buski
Echinostoma ilocanum
Clonorchis sinensis
Infection with this fluke is acquired by eating the tissues of fresh water crabs:
Heterophyes heterophyes
Paragonimus westermani
Clonorchis sinensis
Fasciolopsis buski
Paragonimus westermani
Schistosoma cercaria enter the human body:
By eating raw snail
By eating contaminated vegetables and fish
By blood transfusion
By skin penetration
By skin penetration
Human tapeworm that does not require an intermediate host to complete its natural life cycle:
Hymenolepis nana
Hymenolepis diminuta
Taenia saginata
Dipylidium caninum
Hymenolepis nana
Microfilaria is sheathed, the body nuclei extend almost to the tip of the tail
Wuchereria bancrofti
Brugia malayi
Loa loa
Onchocerca volvulus
Loa loa
The term “internal autoinfection” is generally used in referring to infections with:
Ascaris lumbricoides
Necator americanus
Trichuris trichiura
Strongyloides stercoralis
Strongyloides stercoralis
A fibrous skin nodule is removed from the back of a patient from Central America. A microfilaria seen upon microscopic exam of the nodule is:
Wuchereria bancrofti
Brugia malayi
Onchocerca volvulus
Loa loa
Onchocerca volvulus
Cysticercosis is caused by the disseminated larva of:
Hymenolepis nana
Hymenolepis diminuta
Taenia saginata
Taenia solium
Taenia solium
A tapeworm with almond-shaped or spoon-shaped scolex is:
Taenia saginata
Taenia solium
Dipylidium caninum
Diphyllobothrium latum
Diphyllobothrium latum
An operculated CESTODE egg that can be recovered in human feces is:
Clonorchis sinensis
Paragonimus westermani
Dipylidium caninum
Diphyllobothrium latum
Diphyllobothrium latum
Clonorchis and Paragonimus - TREMATODES, operculated egg
D. caninum - CESTODE, CYLOPHYLLIDEAN, non-operculated egg
D. latum - CESTODE, PSEUDOPHYLLIDEAN, operculated egg
Migrating larva of this parasite can be found in sputum:
Ascaris lumbricoides
Paragonimus westermani
Both of these
None of these
Ascaris lumbricoides
LARVA IN SPUTUM - ASCARIS, STRONGYLOIDES, HOOKWORM
EGG (OVUM) IN SPUTUM - PARAGONIMUS
Egg of this parasite can be found in sputum:
Ascaris lumbricoides
Paragonimus westermani
Both of these
None of these
Paragonimus westerman
LARVA IN SPUTUM - ASCARIS, STRONGYLOIDES, HOOKWORM
EGG (OVUM) IN SPUTUM - PARAGONIMUS
Serve as DEFINITIVE HOST for the beef tapeworm:
Cows, camels
Pigs
Humans
Dogs, cats
Humans
TAENIA SAGINATA
Humans serve as the definitive host for the beef tapeworm, whereas cows/camels serve as intermediate hosts.
INTERMEDIATE HOSTS of Taenia saginata:
Cows, camels
Pigs
Humans
Dogs, cats
Cows, camels
TAENIA SAGINATA
Humans serve as the definitive host for the beef tapeworm, whereas cows/camels serve as intermediate hosts.
Eggs can be confused with POLLEN GRAINS:
Enterobius
Trichuris
Taenia
Dipylidium
Taenia
BAILEY & SCOTT’S: TAENIA EGGS
Eggs can be confused with pollen grains (handle all proglottids with extreme care)
Gravid proglottids resemble rice grains (dry) or cucumber seeds (moist):
Diphyllobothrium latum
Dipylidium caninum
Hymenolepis nana
Hymenolepis diminuta
Dipylidium caninum
BAILEY & SCOTT’S: DIPYLIDIUM CANINUM
Gravid proglottids resemble rice grains (dry) or cucumber seeds (moist).
Parasite recovery from stool may be enhanced by the Baermann funnel technique:
Ascaris lumbricoides
Enterobius vermicularis
Strongyloides stercoralis
Trichinella spiralis
Strongyloides stercoralis
Consumption of the infective larval stage encysted on aquatic plants that have not been cooked results in infection with:
Clonorchis sinensis
Fasciola hepatica
Heterophyes heterophyes
Paragonimus westermani
Fasciola hepatica
A schistosoma egg with a terminal spine would be most likely found in which of the following?
Feces
Bile
Sputum
Urine
Urine
S. HAEMATOBIUM - URINE
The motile, reproducing, feeding stage of the protozoans is which of the
following?
Cyst
Trophozoite
Ova (egg)
Adult worm
Trophozoite
Which of the following organs of the body is most often involved in
extraintestinal amoebiasis?
Lungs
Kidneys
Pancreas
Liver
Liver
Amoeba that inhibit the gastrointestinal tract of man are non-motile, nonfeeding, and infective during which stage?
Pseudopod
Cyst
Trophozoite
Cryptozoite
Cyst
Which of these trophozoites, when acting as a pathogen, is likely to
ingest red blood cells of the host?
Entamoeba coli
Entamoeba hartmanni
Entamoeba histolytica
Endolimax nana
Entamoeba histolytica
The point of differentiation between Entamoeba histolytica and Entamoeba hartmanni is:
Presence of peripheral chromatin
Presence of chromatoid bodies
Only one possesses a cyst form
Size
Size
Failure to find bacteria in purulent spinal fluid should alert one to the
possibility of an infection with:
Viruses
Amoeba
Flagellates
Worms
Amoeba
Which of the following would have a double-walled, wrinkled cyst form?
Naegleria fowleri
Entamoeba hartmanni
Acanthamoeba castellanii
Dientamoeba fragilis
Acanthamoeba castellanii
A cyst that possesses a single nucleus and a large glycogen vacuole that
stains deeply with iodine belong to:
Endolimax nana
Iodamoeba butschlii
Dientamoeba fragilis
Entamoeba coli
Iodamoeba butschlii
Amoeba inhabiting the central nervous system enter the body through the:
Mouth
Nasal mucosa
Urine
Joint fluid
Nasal mucosa
In which specimen are Acanthamoeba and Naegleria usually found?
Blood
Cerebrospinal fluid
Urine
Joint fluid
Cerebrospinal fluid
Which of the following are often mistaken for cysts of amoeba?
Blastocystis hominis
Calcium carbonate crystals
Ammonium magnesium phosphate crystal
Epithelial cells
Blastocystis hominis
Which of the following is pathognomonic for Giardia lamblia and the stage it is found in?
Spiral groove/trophozoite
Undulating membrane/cyst
Cytostome/trophozoite
Ventral sucking disk/trophozoite
Ventral sucking disk/trophozoite
Which of the following protozoa have an undulating membrane?
Trichomonas
Trypanosoma
Chilomastix
Trichomonas and Trypanosoma
Trichomonas and Trypanosoma
A pear-shaped flagellate with jerky motility that is found in a urine specimen is identified as:
Trichomonas hominis
Trichomonas vaginalis
Escherichia coli
Leptospira
Trichomonas vaginalis
Eighty (80) percent of the trophozoites of Dientamoeba fragilis have:
2 nuclei
3 nuclei
1 nuclei
No nuclei
2 nuclei
The only bilaterally symmetrical protozoan is:
Trichomonas
Dientamoeba
Giardia
Balantidium
Giardia
Which of the following is the vector of African sleeping sickness?
Reduviid bug (Triatoma)
Sandfly (Phlebtomus)
Tsetse fly (Glossina)
Ticks
Tsetse fly (Glossina)
How is Trypanosma cruzi transmitted?
Inhalation
Bite of the tsetse fly
Bite of the reduviid bug
Sexual contact
Bite of the reduviid bug
In the laboratory diagnosis of Leishmania donovani, which is the
preferred specimen in which to find Leishman-Donovan bodies?
Bone marrow
Blood
Vaginal secretions
Cerebrospinal fluid
Bone marrow
Which of the following is the only ciliate that is pathogenic in humans?
Babesia
Isospora
Balantidium coli
Entamoeba coli
Balantidium coli
Structure used for motility of Balantidium coli:
Flagella
Cilia
Pseudopodia
Undulating membrane
Cilia
Which nucleus of the trophozoite of Balantidium coli is the reproductive one?
Micronucleus
Macronucleus
Both of these
None of these
Micronucleus
Which of the malarial organisms presents as pale, very AMOEBOID RING TROPHOZOITE, infecting a large pale red blood cell with dot of hemoglobin?
Plasmodium ovale
Plasmodium malariae
Plasmodium falciparum
Plasmodium vivax
Plasmodium vivax
Which of the malarial organism preferentially invades reticulocytes?
Plasmodium falciparum
Plasmodium malariae
Plasmodium vivax
All of the above
Plasmodium vivax
The malarial organism whose schizont resembles a “fruit pie” in which the merozoites form a rosette around the malarial pigment is:
Plasmodium malariae
Plasmodium vivax
Plasmodium ovale
Plasmodium falciparum
Plasmodium malariae
Which malarial organism characteristically has a BAND FORM trophozoite stretching across the red blood cell?
Plasmodium malariae
Plasmodium ovale
Plasmodium vivax
Plasmodium falciparum
Plasmodium malariae
Which malarial organism features ring trophozoites that have double
chromatin dots, applique forms, and often have multiple parasites in the
infected red blood cells?
Plasmodium vivax
Plasmodium falciparum
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
Which malarial organism has large, coarse, red dots within a large, pale red blood cell with fimbriated edges?
Plasmodium vivax
Plasmodium falciparum
Plasmodium ovale
Plasmodium malariae
Plasmodium ovale
The sexual reproduction cycle in Plasmodium and coccidian is referred to as:
Sporogony
Schizogony
Sporocyst
None of the above
Sporogony
What is the infective stage of malarial parasite to the vector?
Cryptozoites
Trophozoites
Gametocyte
Ookinete
Gametocyte
What is the infective stage of malarial parasite to humans?
Gametocytes
Cryptozoites
Schizonts
Sporozoites
Sporozoites
In which type of malaria is there synchronized rupture of the red blood cells every 72 hours?
P. falciparum
P. ovale
P. vivax
P . malariae
P . malariae
Which hemoglobin is incompatible with malaria parasite survival?
Hb CC
Hb F
Hb SS
Hb A
Hb SS
What is the name of the laboratory test that allows laboratory-bred reduviid bugs to feed on patients suspected of having Chagas’ disease?
Complement fixation
Serodiagnosis
Xenodiagnosis
Western blot
Xenodiagnosis
What is both the definitive and intermediate host of Toxoplasma gondii?
Dog
Cow
Cat
Chicken
Cat
What constitutes a positive result in the Sabin-Feldman dye test?
Toxoplasma becomes nonmotile
Toxoplasma can no longer be demonstrated as an intracellular organism
Toxoplasma loses its affinity for methylene blue dye
The mouse into which the immune serum is injected does not die from
toxoplasmosis
Toxoplasma loses its affinity for methylene blue dye
Which of the following tests is used for the detection of Cryptosporidium?
Sabin-Feldman dye test
G-6-PD test
Xenodiagnosis
Sheather’s sugar flotation
Sheather’s sugar flotation
Direct examination of stool specimens stained with iodine make the trophozoite of the protozoa stain what color?
Yellow
Brown
Trophozoites are destroyed by iodine
Do not stain
Trophozoites are destroyed by iodine
The modified acid-fast stain is most often used in parasitology to identify:
Protozoan cysts and trophozoites
Helminth eggs
Plasmodium
Cryptosporidium and other coccidia
Cryptosporidium and other coccidia
Microsporidial infections can be confirmed using:
Light microscopy and modified trichrome stains
Phase contrast microscopy and routine trichrome stains
Electron microscopy and modified acid-fast stains
Fluorescence microscopy and hematoxylin stains
Light microscopy and modified trichrome stains
An infection with microsporidia can be confirmed using modified trichrome stains (10X the normal dye content found in routine trichrome stains) and light microscopy. The internal polar tubule will be visible within some of the spores; this will serve as confirmation of the infection.
What morphological characteristic differentiates trichomonads from other intestinal flagellates?
Sucking disc
Undulating membrane
Cytostome
Axonemes
Undulating membrane
Shown to be related to GAY BOWEL SYNDROME:
Giardia lamblia
Entamoeba histolytica
Balantidium coli
Isospora belli
Giardia lamblia
Important risk factors for Giardiasis include: poor hygiene, poor sanitation, overcrowding,
immunodeficiency, bacterial and fungal overgrowth in the small intestine, and homosexual
practices. Giardiasis has been shown to be related to the “GAY BOWEL SYNDROME.”
Which of the following is the most important feature in differentiating
cysts of Entamoeba histolytica from E. dispar?
Number of nuclei
Size of the cyst
Shape of the karyosome
Distinguishing surface antigens by immunologic assays
Distinguishing surface antigens by immunologic assays
E. histolytica and E. dispar cannot be morphologically differentiated. The cyst stage of
both organisms has four nuclei with a centrally located karyosome. E. histolytica is a well
recognized intestinal parasite, whereas E. dispar is considered nonpathogenic.
Immunologic assays to detect antigens or molecular biology assays are necessary to
differentiate these two species.
Which of the following is the preferred anticoagulant for preparing blood
smears for diagnosing malaria?
EDTA
Heparin
Sodium citrate
Sodium fluoride
EDTA
Collection of blood by finger stick is preferred for preparing blood smears for the detection
of malaria. When a venipuncture is performed, the preferred anticoagulant for malarial
blood smears is EDTA. Heparin can be used, but it may cause distortion of some parasite forms.
A free-living ameba that causes primary amebic meningoencephalitis is:
Dientamoebafragilis
Entamoeba coli
Entamoeba histolytica
Naegleria fowleri
Naegleria fowleri
Naegleria fowleri is found in freshwater ponds and lakes, especially those with disturbed
or suspended soil. It has caused a number of cases of meningoencephalitis in people who
have swum in these bodies of water. Essentially, all these infections have been fulminating
and fatal, and they are often not diagnosed until autopsy.
Which of the following is the best technique to identify Dientamoeba fragilis in stool?
Formalin concentrate
Trichrome-stained smear
Modified acid-fast–stained smear
Giemsa stain
Trichrome-stained smear
Because there is no known cyst form, the best technique to recover and identify D. fragilis
trophozoites would be the trichrome-stained smear.
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:
Trichomonas tenax
Entamoeba histolytica/E. dispar
Entamoeba polecki
Entamoeba gingivalis
Entamoeba gingivalis
E. gingivalis is known to be an inhabitant of the mouth and is characterized by morphology
that resembles Entamoeba histolytica/E. dispar. However, E. gingivalis tends to ingest PMNs, whereas Entamoeba histolytica/E. dispar do not.
In an outbreak of diarrheal disease traced to a municipal water supply, the
most likely causative agent is:
Cryptosporidium spp.
Cystoisospora belli
Entamoeba histolytica
Dientamoeba fragilis
Cryptosporidium spp.
Cryptosporidium oocysts have been transmitted through contaminated municipal water
supplies. Such outbreaks have been well documented.
Plasmodium vivax and Plasmodium ovale are similar because they:
Exhibit Schüffner’s dots and have a true relapse in the life cycle
Have no malarial pigment and multiple rings
Have true stippling, do not have a relapse stage, and infect old red cells
Commonly have appliqué forms in the red cells
Exhibit Schüffner’s dots and have a true relapse in the life cycle
Both P. vivax and P. ovale infect young red cells, have true stippling (Schüffner’s dots),
contain malarial pigment, and have a true relapse stage in the life cycle.
Early ring stages of the fifth human malaria, Plasmodium knowlesi, resemble those of:
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
Plasmodium vivax
Plasmodium falciparum
The early ring stages of Plasmodium knowlesi resemble those of P. falciparum
Older developing stages (trophs, schizonts) of the fifth human malaria,
Plasmodium knowlesi, resemble those of:
Plasmodium malariae
Plasmodium ovale
Plasmodium falciparum
Plasmodium vivax
Plasmodium malariae
The older developmental stages of Plasmodium knowlesi (trophs, schizonts) resemble
those seen in infections with P. malariae (band forms, rosette schizonts).
Autofluorescence requires no stain and is recommended for the identification of:
Entamoeba histolytica cysts
Toxoplasma gondii tachyzoites
Dientamoeba fragilis trophozoites
Cyclospora cayetanensis oocysts
Cyclospora cayetanensis oocysts
Autofluorescence requires no stain and is often recommended for confirmation of
Cyclospora cayetanensis oocysts.
