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PARA > PARA by Ebora > Flashcards

PARA by Ebora Flashcards

1
Q

Trophozoite forms of amoebae are found in what type of stool specimen?

a. Formed
b. Loose
c. Soft
d. Watery

A

Watery

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2
Q

Which preservation method is most suitable and the most widely used for subsequent fixed smear preparation?

a. Formalin-ethyl acetate
b. PVA
c. Trichrome
d. MIF

A

PVA

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3
Q

If the ova of this parasite are ingested by humans, the oncosphere form can migrate through the body via the bloodstream, resulting in
the condition known as cysticercosis. Which of the following is correct?

a. Taenia solium
b. Entamoeba histolytica
c. Hymenolepis nana
d. Clonorchis sinensis

A

Taenia solium

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4
Q

Ova recovered from the stool are routinely used to diagnose infections caused by all of the following except?

a. Necator americanus
b. Ascaris lubricoides
c. Trichuris trichiura
d. Strongyloides stercoralis

A

Strongyloides stercoralis

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5
Q

An MLS finds an E. coli cyst on a wet mount of a fresh stool specimen. Which of the following should be done?

a. Request a second specimen
b. Look for additional E. coli cysts
c. Examine the remaining area of the wet preparation
d. Generate a final report

A

Examine the remaining area of the wet preparation

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6
Q

Which of the following parasites have migration through the lungs as part of their lifecycle?

a. Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis
b. Giardia lamblia, Wuchereria bancrofti, Brugia malayi
c. Enterobius vermicularis, Trichuris trichiura, Trichinella spiralis
d. Toxocara canis, Toxoplasma gondii, Blastocystis homini

A

Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis

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7
Q

Enterobius vermicularis infection is usually diagnosed by finding

A. Eggs in perianal specimens
B. Larvae in perianal specimens
C. Larvae in feces
D. Eggs in the feces

A

Eggs in perianal specimens

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8
Q

The best direct diagnosis of Echinococcus granulosus infection in humans is made by identification of

A. Adult worms in the intestine
B. Adult worms in tissues
C. Eggs in feces
D. Hydatid cysts in tissues

A

Hydatid cysts in tissues

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9
Q

How many stool samples should be collected when following the typical O&P collection protocol?

a. 1
b. 2
c. 3
d. 4

A

3

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10
Q

The only known human tapeworm with an operculum is:

a. Diphyllobothrium latum
b. Hymenolepis nana
c. Giardia lamblia
d. Schistosoma haematobium

A

Diphyllobothrium latum

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11
Q

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

A

Echinococcus granulosus—routine ova and parasite examination

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12
Q

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

A

Eosinophils

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13
Q

Parasitic organisms that are most often transmitted sexually include:

A. Entamoeba gingivalis
B. Dientamoeba fragilis
C. Trichomonas vaginalis
D. Diphyllobothrium latum

A

Trichomonas vaginalis

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14
Q

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

A

The necessity to lake the RBCs during or prior to staining

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15
Q

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

A

Toxocara—serology

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16
Q

What is the vector of African sleeping sickness?

a. Tse tse fly
b. bite of Reduviid bug
c. Anopheles mosquito
d. Sandfly

A

Tse tse fly

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17
Q

RBC inclusion produced by Plasmodium knowlesi

a. Sinton and Mulligan’s stippling
b. Maurer’s clefts
c. Schuffner’s
d. James’ dots

A

Sinton and Mulligan’s stippling

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18
Q

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

A

Modified Ziehl–Neelsen acid-fast stain

**A The oocysts of Cryptosporidium spp. can be found and identified using microscopic examination of fecal smears stained with modified acid-fast stains. They appear as purple-red-pink round objects, measuring approximately 4–6 μ. Often, the four sporozoites and residual body can be seen within the oocyst wall

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19
Q

Elephantiasis is a complication associated with which of the following?

A. Cysticercosis
B. Guinea worm
C. Hydatid cyst disease
D. Filariae

A

Filariae

Elephantiasis:
Brugia malayi: Upper elephantiasis
W. bancrofti: Lower elephantiasis
(Alphabetical order B (upper)→ W [lower])

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20
Q

Which species of malaria parasite usually has ameboid trophozoites and produces small reddish dots in the red blood cell cytoplasm?

A. Plasmodium knowlesi
B. Plasmodium falciparum
C. Plasmodium malariae
D. Plasmodium vivax

A

Plasmodium vivax

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21
Q

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

A

Trypanosoma brucei rhodesiense—bite of sand fleas

East and West African trypanosomiasis (T. b. rhodesiense and T. b. gambiense) are caused when infective forms are introduced into the
human body through the bite of the tsetse fly, not sand fleas

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22
Q

The adult tapeworm of Echinococcus granulosus is found in the intestine of:

A. Dogs
B. Sheep
C. Humans
D. Cattle

A

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

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23
Q

What technique is best used for the recovery of coccidian oocyst (Cryptoporidium, Cyclospora and Isospora)?

a. Sheather’s sugar flotation
b. Zinc sulfate flotation
c. Brine flotation
d. Acid ether concentration technique

A

Sheather’s sugar flotation

Sheather’s sugar floatation → Reagent: Boiled sugar preserved with phenol is the reagent

Brine floatation→ Reagent: saturated table salt solution

Zinc sulfate floatation → For protozoan cysts and nematode eggs except Trichuris and Capillaria. Not able to recover operculated eggs, infertile
ascaris eggs and schistosomes

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24
Q

What nematode is known as the pinworm

a. Enterobius vermicularis
b. Capillaria philippinensis
c. Ascaris lumbricoides
d. Trichuris trichiura

A

Enterobius vermicularis

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25
Q

Malaria parasite have their asexual cycle in?

a. man
b. mosquito
c. both
d. neither

A

man

Sexual phase is found in mosquito

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26
Q

What is the largest protozoa that has cells, and causes severe intestinal infection?

a. Balantidium coli
b. E. coli
c. Giardia lamblia
d. T. tenax

A

Balantidium coli

Only ciliate capable of causing infection to humans

Habitat: colon

Risk factor: close contact with pigs/ pigs feces
“Thrown ball motility”

Virulence factor: hyaluronidase (Lytic enzyme that causes ulceration). Enzyme causing destruction causing shigellosis / dysentery like disease.
Causes ulcers bigger than E. histolytica

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27
Q

Which of the following is the most important feature in differentiating cysts of Entamoeba histolytica from E. dispar?

A. Number of nuclei
B. Size of the cyst
C. Shape of the karyosome
D. Distinguishing surface antigens by immunologic assay

A

Distinguishing surface antigens by immunologic assay

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

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28
Q

The disease most commonly associated with Acanthamoeba sp. is

A. Diarrhea
B. Keratitis
C. Liver abscess
D. Meningoencephalitis

A

Keratitis

Acanthamoeba is a free-living ameba rarely causing human infections. This organism has been associated with granulomatous infections of the skin and lung, as well as meningoencephalitis. However, the most common presentation is keratitis, infection of the cornea. Most keratitis
cases have been associated with contact lenses

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29
Q

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

A

Series of Scotch tape preparations

In a pediatric patient, the most appropriate diagnostic test for recovery of Enterobius vermicularis eggs is a series of Scotch tape preparations.

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30
Q

Cysts are the infective stage of this intestinal flagellate.

A. Balantidium coli
B. Dientamoeba fragilis
C. Entamoeba coli
D. Giardia lamblia

A

Giardia lamblia

Cysts are the infective stage of most intestinal parasites. D. fragilis is currently classified as a flagellate, even though it does not produce a flagellum. However, D. fragilis does not have a cyst stage. G. lamblia is the only flagellate in the list of protozoa with a cyst stage. B. coli is a ciliate and E. coli is an ameba.

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31
Q

Many parasites have different stages of growth within different hosts. The host where the sexual reproductive stage of the parasites exists is called the

A. Commensal
B. Definitive host
C. Intermediate host
D. Vector

A

Definitive host

In parasites with a sexual and asexual stage of development, the definitive host is the host in which the sexual stage of the parasite occurs.
The intermediate host is the host in which the asexual stage of the parasite is found.
Vectors are arthropods, like mosquitoes and ticks that transmit infectious agents. A commensal is an organism that benefits from an existence with a host but does not damage the host.

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32
Q

Acceptable stool sample size

a. 2 to 5 grams
b. 5 to 8 grams
c. 10 grams
d. 4 to 8 grams

A

2 to 5 grams

and pea sized

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33
Q

The zoonotic disease known as creeping eruption is caused by:

a. Ascaris lumbricoides
b. Ancylostoma braziliense
c. Dirofilaria spp.
d. Toxocara canis

A

Ancylostoma braziliense

Creeping eruption is caused by ANIMAL HOOKWORMS
- Ancylostoma caninum
- Ancylostoma braziliense

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34
Q

Human infection with Loa loa is best diagnosed by which of the following?

a. Examination of an infected Anopheles mosquito
b. Examination of blood smears
c. Examination of feces
d. Examination of a skin scraping

A

Examination of blood smears

In general the diagnosis of L. loa infection should be made with blood smear. However, when blood smears are negative and clinical
suspicion of infection is high, the general antibody test could be used in an attempt to exclude infection.

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35
Q

A child who plays in dirt contaminated with human and pet feces is susceptible to which of the following set of parasites?

a. Ascaris lumbricoides, Trichuris trichiura, Trichinella spiralis, Wuchereria bancrofti
b. Loa loa, Capillaria philippinensis, Enterobius vermicularis, Trichinella spiralis
c. Strongyloides stercoralis, Toxocara canis, Ascaris lumbricoides, Necator americanus
d. Ancylostoma braziliense, Trichuris trichiura, Trichinella spiralis, Necator americanus

A

Strongyloides stercoralis, Toxocara canis, Ascaris lumbricoides, Necator americanus

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36
Q

All of the following adult parasites live in the intestinal tract EXCEPT:

a. Ascaris lumbricoides
b. Enterobius vermicularis
c. Loa loa
d. Trichinella spiralis

A

Loa loa

Maturing larvae and adults of the “eye worm” occupy the subcutaneous layer of the skin – the fat layer – of humans, causing disease. The L. loa adult worm which travels under the skin can survive up to 10–15 years, causing inflammations known as Calabar swellings.

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37
Q

Each of the following microfilaria has a sheath EXCEPT:

a. Brugia malayi
b. Loa loa
c. Mansonella ozzardi
d. Wuchereria bancrofti

A

Mansonella ozzardi

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38
Q

Ascaris lumbricoides

For each of the following, match the diagnostic technique(s) associated with the given parasite. Note: Choices may be used more than once or
not at all.

a. Blood film examination
b. Cellophane tape test
c. Fecal concentration method
d. Tissue biopsy
e. Serologic test

A

Fecal concentration method

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39
Q

Strongyloides stercoralis

For each of the following, match the diagnostic technique(s) associated with the given parasite. Note: Choices may be used more than once or
not at all.

a. Blood film examination
b. Cellophane tape test
c. Fecal concentration method
d. Tissue biopsy
e. Serologic test

A

Fecal concentration method

40
Q

Trichinella spiralis

For each of the following, match the diagnostic technique(s) associated with the given parasite. Note: Choices may be used more than once or
not at all.

a. Blood film examination
b. Cellophane tape test
c. Fecal concentration method
d. Tissue biopsy
e. Serologic test

A

Tissue biopsy

41
Q

Wuchereria bancrofti

For each of the following, match the diagnostic technique(s) associated with the given parasite. Note: Choices may be used more than once or
not at all.

a. Blood film examination
b. Cellophane tape test
c. Fecal concentration method
d. Tissue biopsy
e. Serologic test

A

Blood film examination

42
Q

A patient presents with vague abdominal pains and a microcytic hypochromic anemia. A possible causative parasite is:

a. Enterobius vermicularis
b. Ancylostoma duodenale
c. Brugia malayi
d. Trichinella spiralis

A

Ancylostoma duodenale

43
Q

An immunosuppressed patient is susceptible to autoreinfection with which one of the following nematodes?

a. Strongyloides stercoralis
b. Trichinella spiralis
c. Ascaris lumbricoides
d. Trichuris trichiura

A

Strongyloides stercoralis

44
Q

Paragonimus westermani infection is acquired by:

a. Drinking contaminated water
b. Eating infected crustacea
c. Eating infected fish
d. Eating infected water chestnuts

A

Eating infected crustacea

45
Q

The preferred specimen for the diagnosis of paragonimiasis is:

a. Bile drainage
b. Duodenal aspirate
c. Rectal biopsy
d. Sputum

A

Sputum

46
Q

The three species of human blood flukes have as intermediate host:

a. A cyclops
b. An aquatic snail
c. An insect
d. A freshwater fish

A

An aquatic snail

47
Q

Blackwater fever is caused by:

a. Plasmodium falciparum
b. Plasmodium vivax
c. Trypanosoma brucei gambiense
d. Trypanosoma cruzi
e. Leishmania donovani

A

Plasmodium falciparum

48
Q

Winterbottom’s sign is associated with:

a. Babesia microti
b. Leishmania donovani
c. Plasmodium falciparum
d. Trypanosoma brucei gambiense
e. Trypanosoma cruzi

A

Trypanosoma brucei gambiense

49
Q

Fecal samples should be washed with saline only because washing with water will destroy:

a. Blastocystis hominis
b. Cryptosporidium spp.
c. Entamoeba cysts
d. Cystoisospora belli
e. Acanthamoeba spp.

A

Blastocystis hominis

Classified member of Stramenopiles
* Suggested new class: Class Blastocystea
* Previously classified as a yeast in Schizosaccharomyces
* Also previously associated with Blastomyces
* MOT: ingestion of thick walled cysts
* Life cycle still not fully understood

50
Q

The characteristic that most clearly differentiates cysts of lodamoeba bütschlii from other amebic cysts is (are):

a. Chromatoid bars with rounded ends
b. Eight nuclei with eccentrically located karyosomes
c. Ingested bacteria and red blood cells
d. A large glycogen vacuole
e. Lemon-shaped cysts

A

A large glycogen vacuole

51
Q

A blood parasite that invades reticulocytes, is characterized by single ring forms and Schüffner’s dots, and may cause a true relapse is:

a. Babesia spp.
b. Plasmodium falciparum
c. Plasmodium malariae
d. Plasmodium ovale
e. Plasmodium vivax

A

Plasmodium vivax

52
Q

Material from a gum lesion is stained with trichrome, revealing amebae that have a single nucleus and contain partially digested neutrophils. The most likely identification is:

a. Entamoeba gingivalis
b. Entamoeba dispar
c. Entamoeba polecki
d. Trichomonas tenax
e. Entamoeba histolytica

A

Entamoeba gingivalis

➔ Entamoeba gingivalis
◆ Ameba of oral cavity (gum line)
◆ No cyst stage = IS: trophozoite
◆ MOT: person to person (kissing; sharing of personal items)
◆ First ameba discovered by man
◆ Found inhabiting the gum line of teeth, tartar and gingival pockets of teeth of unhealthy mouths and even healthy mouths; may also be seen in
genital tract
◆ Scavengers and eat debris; can ingest WBCs, debris, RBC (rare)
◆ Non-pathogenic; but seen in patients with pyorrhea alveolaris (gum infection)

53
Q

Acanthamoeba keratitis is usually associated with:

a. Contaminated lens-cleaning solutions
b. Hard contact lenses
c. Soft contact lenses
d. Wearing lenses while swimming
e. Swimming without lenses

A

Contaminated lens-cleaning solutions

54
Q

The organism responsible for Lyme disease is transmitted to humans by:

a. Ixodes spp.
b. Dermacentor spp.
c. Borrelia burgdorferi
d. Mansonia spp.
e. Phthirus pubis

A

Ixodes spp.

Babesia spp. (Babesiosis) and Borrelia burgdorferi
- Co infection since both share same tick vector
- Same endemic area

55
Q

Yersinia pestis is transmitted by:

a. Dermacentor spp.
b. Pediculus spp.
c. Sarcoptes scabiei
d. Xenopsylla spp.

A

Xenopsylla spp.

The rat flea, Xenopsylla cheopis, is the primary vector of the bubonic plague bacterium, Yersinia pestis, and also serves as a vector of bacteria belonging to the genera Rickettsia and Bartonella.

56
Q

The formalin-ethyl acetate concentration method for feces is used to demonstrate:

a. Formation of amebic pseudopodia
b. Hatching larval forms
c. Motility of helminth larvae
d. Protozoan cysts and helminth eggs
e. Trophozoites

A

Protozoan cysts and helminth eggs

57
Q

Ameba trophozoite motility is best observed using a(n):

a. Iodine-stained wet mount
b. Unstained saline wet mount
c. Unstained zinc sulfate flotation preparation
d. Concentrated wet mount
e. Giemsa stain

A

Unstained saline wet mount

58
Q

Which of the following exhibits diurnal periodicity?

a. Wuchereria bancrofti
b. Brugia malayi
c. Loa loa
d. Onchocerca volvulus

A

Loa loa

Wuchereria bancrofti: nocturnal
Brugia malayi: subperiodic (12 pm to 8pm)
Loa loa: diurnal → during the day
Onchocerca volvulus: nonperiodic

59
Q

Which of the following causes primary amoebic meningoencephalitis?

a. Entamoeba histolytica
b. Babesia spp.
c. Naegleria spp.
d. Sarcocystis spp.

A

Naegleria spp.

Granulomatous Amebic encephalitis is caused by Acanthamoeba

60
Q

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

A

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

61
Q

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

A

Ingestion of raw freshwater fish

The ingestion of raw freshwater fish containing the encysted larvae of D. latum will result in the development of an adult tapeworm within the
human intestine

62
Q

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

A

Short buccal capsule and large genital primordium

The rhabditiform larvae of S. stercoralis are characterized by the short buccal capsule (mouth) and large genital primordium, whereas
hookworm larvae have a long buccal capsule and very small genital primordium.

63
Q

The trichrome stain is used to identify:

a. Blood protozoa
b. Helminth eggs in feces
c. Intestinal protozoa
d. Antibodies to tissue parasite

A

Intestinal protozoa

A permanent stain—such as the trichrome stain used on a thin, fixed fecal smear—is particularly helpful in allowing identification of nuclear and
other intracellular structures and is highly recommended as a routine procedure in a diagnostic laboratory

64
Q

Which of the following is the preferred anticoagulant for preparing blood smears for diagnosing malaria?

A. EDTA
B. Heparin
C. Sodium citrate
D. Sodium fluoride

A

EDTA

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 (ethylenediaminetetraacetic acid). Heparin can be used, but it may cause distortion of some parasite forms.

65
Q

Which of the following is the most important feature in differentiating cysts of Entamoeba histolytica from E. dispar?

A. Number of nuclei
B. Size of the cyst
C. Shape of the karyosome
D. Distinguishing surface antigens by immunologic assays

A

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 wellrecognized intestinal parasite, whereas E. dispar is considered nonpathogenic. Immunologic assays to detect antigens or molecular biology assays are necessary to differentiate these two species

66
Q

With a fecal specimen, which one of the following is the most dependable procedure for the accurate, specific diagnosis of an intestinal
amebic infection?

A. Direct saline wet mount
B. Direct iodine wet mount
C. Permanently stained smear
D. Formalin-ethyl acetate sedimentation technique

A

Permanently stained smear

The permanently stained smear is especially recommended for identification of trophozoites, for confirmation of species, and for keeping a permanent record of the organisms found. Species identification of amebic trophozoites can rarely be made from a single
feature; permanent stains enable one to observe the cytoplasm and cytoplasmic inclusions and the nuclear morphologic features of
many cells. Iron hematoxylin and trichrome are commonly used stains

67
Q

In an examination of stained blood films, Babesia spp. are likely to resemble

A. Leishmania donovani
B. Plasmodium falciparum
C. Toxoplasma gondii
D. Trypanosoma cruzi

A

Plasmodium falciparum

68
Q

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

A

Giardia lamblia – falling leaf

Balantidium coli- thrown ball motility/ rolling ball

Chilomastix mesnili – corkscrew/ boring

Trichomonas hominis- jerky motility. → Updated name: Pentatrichomonas hominis: found in contaminated food, water fomites.
- habitat: colon
- has 5 flagella

69
Q

The following parasites are capable of autoinfection, except

a. Cryptosporidium hominis
b. Enterobius vermicularis
c. Taenia solium
d. Hymenolepis nana
e. none of the above

A

none of the above

CHETS
Capillaria philippinensis
Hymenolepis nana
Enterobius vermicularis
Taenia solium
Strongyloides stercoralis

In addition, unlike other parasites belonging to the same subclass (Coccidia), Cryptosporidium is able to autoinfect the same host. Autoinfection
occurs through the thin-walled oocysts, which excyst once they are separated from the epithelium, and the cycle starts again

70
Q

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 Country
D. Fever patterns, travel history, diet

A

Travel history, antimalarial medication, date of return to Country

Travel history (areas of drug resistance), the date of return to the United States (primary versus relapse case), and history of antimalarial
medication and illness (severe illness, few organisms on smear) are very important questions to ask. Without this information, a malaria
diagnosis can be missed or delayed with severe patient consequences

71
Q

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

A

Strongyloides stercoralis

latent infection with S. stercoralis acquired years before may cause severe symptoms in the immunosuppressed patient (“autoinfective”
capability of life cycle and migratory route of the larvae through the body)

72
Q

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

A

Blood films for malaria

The request for blood films for malaria should always be considered a stat request. Any laboratory providing these services should be available 24 hours a day, 7 days a week. In cases of P. falciparum malaria, any delay in diagnosing the infection could be fatal for the patient

73
Q

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

A

Enterobius vermicularis, the pinworm

The pinworm, E. vermicularis, is the most common parasitic helminth infection throughout the world, and the eggs are infective within just a few
hours. Some have said, “You either had the infection as a child, have it now, or will have it again when you have children.”

74
Q

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

A

Trichuris trichiura

The eggs of T. trichiura (the whipworm) have been described as being barrel shaped with a thick shell and two polar plugs

75
Q

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

A

Exhibit Schüffner’s dots and have a true relapse in the life cycle

A 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.

76
Q

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

A

Plasmodium malariae

The older developmental stages of Plasmodium knowlesi (trophs, schizonts) resemble those seen in infections with P. malariae (band forms, rosette schizonts).

77
Q

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

A

Plasmodium falciparum

The early ring stages of Plasmodium knowlesi resemble those of P. falciparum.

78
Q

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

A

Rapid erythrocytic cycle (24 hr), will infect all ages of RBCs, and can cause serious disease

A 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.

79
Q

Chagas disease (American trypanosomiasis) is caused by

A. Tiypanosoma brucei
B. Trypanosoma cruzi
C. Leishmania braziliensis
D. Dracunculus medinensis

A

Trypanosoma cruzi

  • Belongs to Trypanosome Group Stercoraria
  • Primarily infects: myocytes, heart cells, and RESs (reticuloendothelial system: monocytes, macrophages, skin, gonads, intestinal mucosa, placenta etc., so it is intracellular)
  • Causes Chagas’ Disease (Dr. Chagas first to study the disease) or American Trypanosomiasis (because of high prevalence in America)
  • Found in the PH (but no cases)
    o Found in squalid areas or dirty areas, mud walls
  • Infective stage to humans: metacyclic trypomastigote
  • Multiply within the mammalian host in a discontinuous manner
  • Zoonotic mammalian reservoir hosts: domestic animals, armadillos, raccoons, rodents, marsupials, and some primates
    FINAL HOST: MAN
80
Q

Hematuria is a typical sign of human infection caused by

A. Trypanosoma cruzi
B. Trichinella spiralis
C. Trichomonas vaginalis
D. Schistosoma haematobium

A

Schistosoma haematobium

81
Q

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

A

Trichinosis

Excretion in human feces of the eggs of the hookworms, Taenia solium, T. saginata, and Ascaris lumbricoid.es, is an essential or
important factor in perpetuating the cycle of infection with these parasites. Trichinosis is caused by ingestion of the live larvae of
Trichinella spiralis encysted in the muscles of a flesh-eating host. The adults live in the host’s intestine, and the viviparous females, after
fertilization, produce larvae that migrate into the host’s muscle tissue

82
Q

readily be identified when crescent-shaped gametocytes are found in stained blood films?

A. P. falciparum
B. P. malariae
C. P. ovale
D. P. vivax

A

P. falciparum

83
Q

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

A

Necator americanus and Ancylostoma duodenale

Eggs that can’t be speciate:
- Taenia
- Fasciola
- Hookworms

84
Q

Diagnosis of infection with W. bancrofti can be accomplished by all of the following methods except

a. Serologic testing
b. Knott technique
c. Tissue biopsies
d. Thick and thin peripheral blood smears

A

Tissue biopsies

85
Q

Diagnosis of infection with W. bancrofti is best accomplished by

a. Examination of stained peripheral blood taken during the night
b. Examination of stained tissue biopsy taken during the night
c. Use of serologic testing with blood taken during the day
d. Examination of stained lymph fluid taken during the day

A

Examination of stained peripheral blood taken during the night

Wuchereria bancrofti
* Has nocturnal periodicity, meaning specimens should be collected at night because this is the time that the parasites are present in the blood

86
Q

Strawberry cervix used by one of the parasitic agent below.

a. T. vaginalis
b. E. histolytica
c. N. gonorrhea
d. T. hominis

A

T. vaginalis

  • Causes Trichomoniasis (STD)
  • Has no cyst stage and has jerky tumbling motility
  • Speculum examination reveals punctate hemorrhages of the cervix (strawberry cervix)
  • Muopurulent discharge that is frothy, yellow, or green is also observed
87
Q

Stool may be presented with formalin solution. This concentration is recommended for protozoan cysts.

a. 10%
b. 5%
c. 30%
d. 40% stock

A

5%

Formalin
* All purpose fixative
* 5%: recommended for protozoan cysts
* 10%: recommended for helminth eggs and larvae
* Solution may be buffered with sodium phosphate to preserve morphological characteristics of the organisms

88
Q

In Zinc sulphate flotation method the ideal specific gravity of the solution is?

a. 1.18 to 1.20
b. 1.004 to 1.022
c. 1.018-1.020
d. 1.20-1.40

A

1.18 to 1.20

Zinc Sulphate Flotation Method
* Main reagent: 33% zinc sulfate solution
* Ideal specific gravity: 1.18-1.20
Page 324 Belizario

89
Q

Stage of schistosomes infective to the mammals.

a. Cercaria
b. Sporocyst
c. Egg
d. Miracidium

A

Cercaria

Schistosoma
* Mode of transmission to humans: skin penetration of the cercaria
* Miracidium: infective stage to snail (1st intermediate
host)
* Miracidium will then develop into a Sporocyst
o Sporocysts will then reproduce asexually to become free swimming cercaria

90
Q

Jacksonian epilepsy is observed in

a. Schistosomiasis
b. Fasciolasis
c. Paragonimiasis
d. Chlonorchiasis
e. Malarial Infection

A

Paragonimiasis

Paragonimus westermani

  • May cause partial seizures and cerebral Paragonimiasis
  • Can cause Jacksonian Epilepsy (discovered by Dr. John Jackson
91
Q

Identifying characteristic of Quartan malaria mature schizonts

a. Band formation
b. Compact
c. Rosette appearance
d. Fimbriated

A

Rosette appearance

Plasmodium malariae
* Causative agent of Quartan Malaria (paroxysmal cycle takes 72 hours)
* Infects old RBCs
* Large trophozoites are in band forms
* Mature schizonts are in rosette form

92
Q

Histidine rich protein II assay is useful for the diagnosis of

a. Malaria
b. Trichomoniasis
c. Amoebiasis
d. Trypanosomiasis

A

MalariaHistidine-rich protein II (HRPII) is a protein produced by P. falciparum but not by other malaria parasite species. It accumulates in the bloodstream [10] and is the basis of diagnostic and prognostic tests for falciparum malaria.

93
Q

NNA (non-nutrient agar) preseeded with E.coli medium is used for cultivation of

a. E.coli
b. B. coli
c. E. nana
d. N. fowleri

A

N. fowleri

94
Q

Which of the following forms of Toxoplasma gondii are produced in infected humans?
A. Bradyzoites
B. Macrogametes
C. Sporoblasts
D. Oocysts

A

Bradyzoites

Toxoplasma gondii
- Parasites of cats
- Complete life cycle in cats
- Humans are accidental/ intermediate hosts
- MOT: ingestion of sporulated oocysts or tissue cysts

Diagnostic stage
- Tissue cysts
* Bradyzoites
▪ Multiply slowly
▪ Develop mostly in neural and muscular tissues
▪ May also develop in visceral organs
▪ Late stages of infection
▪ Enclosed in a tissue cyst

Tachyzoites
▪ Rapidly multiply
▪ Infect cells of the intermediate hosts and non-intestinal epithelial cells of cats
▪ Found in early stages of infection
▪ Crescent-shaped

95
Q

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

A

Are the diagnostic form found in feces

The rhabditiform larvae of S. stercoralis are the diagnostic stage typically passed in the feces of infected persons. The larvae measure up to 380
um long X 20 urn wide. They have a short buccal cavity and a prominent, ovoid, genital primordium midway along the ventral wall of the body. The infective stage is the filariform larva, which differs from the hookworm filariform larva by having a notched tail tip and a long esophagus.

PARA (5 decks)

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