Deck 23: Parasitic Protozoa, Helminths, and Arthropod Vectors

Question 1

Which of the following vectors may spend their entire life associated with a single host individual?

A) lice
B) mites
C) spiders
D) ticks
E) fleas

Answer 1

A

Question 2

Which of the following regarding all of the tapeworms that infect humans is TRUE?

A) They reside in the muscle tissue of the definitive host.
B) They are transmitted by insect vectors.
C) Humans are the normal intermediate hosts.
D) They all have non- human intermediate hosts.
E) The larva can directly infect humans upon contact with skin.

Answer 2

D

Question 3

A contact lens wearer and cat owner begins to experience problems with her eye. The eye is inflamed and painful, and examination of the eye reveals that the conjunctiva is ulcerating. Which of the following parasites could be responsible?

A) Cryptosporidium parvum
B) Toxoplasma gondii
C) Trypanosoma cruzi
D) Entamoeba histolytica
E) Acanthamoeba

Answer 3

E

Question 4

Once infected with Trypanosoma brucei, the patient's immune system cannot clear the infection and develop immunity because the parasite

A) has flagella that allow it to travel all over the body.
B) changes its glycoprotein surface antigens every time it replicates.
C) matures into infectious trypomastigotes.
D) invades the central nervous system.
E) reproduces by binary fission.

Question 5

Nematodes

A) have males of the species larger than females of the species.
B) are known as roundworms.
C) do not have a digestive system.
D) are known as flukes.
E) are all monoecious.

Question 6

Which of the following is a ciliated pathogen of the intestinal tract?

A) Leishmania
B) Trypanosoma
C) Balantidium
D) Giardia
E) Plasmodium

Question 7

Which of the following contributes to infection with Trichomonas vaginalis?

A) careless handwashing habits
B) compromised immunity
C) living in an undeveloped area of the world
D) contact with contaminated fomites
E) preexisting disease (chlamydia, for example)

Question 8

How are the different types of Schistosoma identified?

A) by the treatments they respond to
B) by the location of the swimmer's itch they cause
C) by their intermediate host
D) by the lesion they cause
E) by the position of their spine and the shape of their eggs

Question 9

Which of the following parasites infects the lymphatic system?

A) Fasciola
B) Wuchereria
C) Ascaris
D) Schistosoma
E) Echinococcus

Question 10

Triatoma, commonly called "kissing bugs," are vectors of

A) Chagas' disease.
B) African sleeping sickness.
C) Cyclosporiasis.
D) Leishmania.
E) schistosomiasis.

Question 11

Balantidium coli uses to penetrate the intestinal mucosa.

A) cilia
B) suckers
C) adhesion discs
D) flagella
E) pseudopodia

Question 12

Which of the following statements concerning infection with Toxoplasma is FALSE?

A) It is one of the world's most widely distributed protozoan parasites in humans.
B) The majority of infected people are asymptomatic.
C) It usually results in no permanent damage and is self- limiting.
D) It is typically contracted by eating undercooked meat.
E) Even though it can be transmitted across the placenta, it is harmless to the fetus.

Question 13

The presence of active motile multiflagellated trophozoites in vaginal or urethral secretion is indicative of infection with

A) Chlamydia trachomatis.
B) Balantidium coli.
C) Trichomonas vaginalis.
D) Giardia intestinalis.
E) Acanthamoeba.

Question 14

Which of the following is the most common parasitic worm in the United States?

A) Enterobius vermicularis
B) Schistosoma mansoni
C) Echinococcus granulosus
D) Taenia saginata
E) Ascaris lumbricoides

Question 15

What is a prophylactic drug of choice for malaria?

A) nifurtimox
B) artemisinin
C) tetracycline
D) pyrimethamine
E) proguanil

Question 16

Schistosoma

A) is a roundworm.
B) uses snails as an intermediate host.
C) is a liver fluke.
D) has proglottids.
E) is a cestode.

Question 17

Which of the following is the same for both Trypanosoma cruzi and Trypanosoma brucei?

A) means of entry into the host
B) type of arthropod vector
C) importance of early diagnosis and treatment
D) central nervous system infection
E) where the protozoan matures in the vector

Question 18

Why is snail fever a common name for infections with Schistosoma?

A) Snails are the intermediate host.
B) Infection is contracted by contact with fresh water where the snail intermediate hosts occur.
C) They are contracted by eating snails.
D) The worms look like snails.
E) Physical contact with snails may result in infection.

Question 19

The infectious stage of a beef tapeworm for humans is the

A) gravid proglottids in feces.
B) eggs in contaminated water.
C) cysticerci in beef.
D) larvae in feces.
E) mature worm.

Question 20

Which of the following species of Plasmodium causes cerebral malaria?

A) only P. falciparum
B) P. ovale and P. malariae
C) P. ovale and P. vivax
D) P. vivax and P. malariae
E) P. vivax, P. malariae, and P. vivax

Question 21

Humans become infected with Fasciola by

A) consuming cysticerci in contaminated meat.
B) the penetration of cercariae through the skin.
C) ingesting the encysted metacercariae on watercress or other vegetation.
D) the bite of infected mosquitoes.
E) ingesting water contaminated with eggs shed in infected dog's urine.

Question 22

The vectors of are sand flies.

A) leishmaniasis
B) Chagas' disease
C) beaver fever
D) filariasis
E) giardiasis

Question 23

What do Echinococcus granulosus, Entamoeba histolytica, and Enterobius vermicularis have in common?

A) They live in the intestines of their definitive host.
B) They are transmitted by insect vectors.
C) They are diagnosed by examination of a blood smear.
D) They cause zoonoses in humans.
E) They are intracellular parasites.

Question 24

A human fecal sample is examined and found to contain a few strobila. The person is probably infected with

A) Giardia intestinalis.
B) Schistosoma.
C) Echinococcus granulosus.
D) Necator americanus.
E) Taenia.

Question 25

Which of the following organisms can colonize the nasal cavity and enter the brain to cause meningoencephalitis?

A) Acanthamoeba
B) Naegleria
C) Balantidium
D) Giardia
E) Entamoeba histolytica

Question 26

Which of the following is transmitted by the fecal- oral route?

A) Entamoeba histolytica
B) Trichomonas
C) Plasmodium
D) Schistosoma and Trichomonas
E) Schistosoma

Question 27

Which form of Leishmania lacks flagella and multiplies in a mammalian host's macrophages?

A) epimastigotes
B) promastigotes
C) trophozoites
D) cystic forms
E) amastigotes

Question 28

Which of the following parasitic infections can be diagnosed using a blood smear?

A) malaria
B) African sleeping sickness
C) toxoplasmosis and malaria
D) toxoplasmosis
E) African sleeping sickness and malaria

Question 29

The tsetse fly is responsible for the spread of

A) filariasis.
B) toxoplasmosis.
C) Chagas' disease.
D) kala- azar.
E) African sleeping sickness.

Question 30

Which of the following nematodes can be transmitted by mosquitoes?

A) Enterobius vermicularis
B) Necator americanus
C) Ascaris lumbricoides
D) Wuchereria bancrofti
E) Ancylostoma duodenale

Question 31

Which of the following is the most common parasitic disease in industrialized nations?

A) toxoplasmosis
B) giardiasis
C) Trichomonas infection
D) balantidiasis
E) schistosomiasis

Question 32

The only helminth disease of humans spread by an insect vector is

A) hydatid disease.
B) filariasis.
C) ascariasis.
D) schistosomiasis.
E) fascioliasis.

Question 33

Severe watery diarrhea with a "rotten- egg" smell accompanied by abdominal pain, bloating, and fever are signs and symptoms consistent with

A) Chagas' disease.
B) cryptosporidiosis.
C) balantidiasis.
D) giardiasis.
E) leishmaniasis.

Question 34

Differentiating between Taenia saginata and Taenia solium is carried out by examination of the

A) eggs.
B) larvae.
C) scoleces.
D) proglottids.
E) cysticerci.

Question 35

Trypanosoma cruzi is introduced into the body by

A) feces containing trypomastigotes contaminating a bite wound.
B) ingesting food contaminated with the parasite.
C) the bite of a tsetse fly, which introduces the trypomastigotes into the body.
D) the bite of a sand fly that has ingested phagocytes containing the parasite.
E) wearing contact lenses cleaned with contaminated tap water.

Question 36

After a trip to several South American countries, a middle- aged man becomes ill. He becomes anemic, loses weight, and runs a fever. The clinician notes a recently healed sore near his nose. Microscopic examination of a blood smear does not reveal anything other than the anemia. What parasitic infection is consistent with this scenario?

A) malaria
B) balantidiasis
C) Chagas' disease
D) giardiasis
E) leishmaniasis

Question 37

The protozoans known as apicomplexans

A) are motile.
B) reproduce by schizogony and are intracellular parasites.
C) reproduce by schizogony.
D) are intracellular parasites.
E) are motile intracellular parasites.

Question 38

A person reports to a clinic complaining of fever and abdominal pain. The abdomen is swollen, and blood tests indicate liver damage. A stool sample is examined under a microscope and found to contain eggs with a spine projecting from its surface. The indications are consistent with infection with

A) Enterobius vermicularis.
B) Echinococcus granulosus.
C) Taenia solium.
D) Ancylostoma duodenale.
E) Schistosoma mansoni.

Question 39

Elephantiasis is caused by

A) filarial roundworms.
B) blood flukes.
C) flatworms.
D) liver flukes.
E) tapeworms.

Question 40

The easiest way to prevent Taenia infection in humans is to

A) vaccinate humans who are in contact with cows and pigs.
B) vaccinate cows and pigs.
C) spray pastures and grazing lands with toxins that kill the parasite.
D) identify patients with cysticerci in their muscles.
E) thoroughly cook or freeze meat.

Question 41

The parasite (Leishmania/Toxoplasma/Trichomonas) is an obligate parasite that is incapable of surviving long outside the human host and is transmitted almost exclusively via sexual activity.

Question 42

Apicomplexans reproduce asexually by (mitosis/schizogony/fission).

Question 43

The primary risk to humans infected with Echinococcus granulosus is

A) formation of hydatid cysts.
B) intestinal obstruction.
C) development of cysticerci.
D) anemia.
E) infection of the fetus.

Question 44

With each wave of replication, (amoebae/plasmodia/trypanosomes) change their glycoprotein surface antigens.

Question 45

The tapeworm's (proglottids/scolex/strobila) reflects a sequence of development.

Question 46

Enterobius vermicularis are commonly known as (pinworms/hookworms/tapeworms) because of the shape of the female's tail.

Question 47

The most common nematode infection worldwide is (ascariasis/filariasis/pinworms).

Question 48

The (definitive/intermediate) host is where immature stages of parasites develop.

Question 49

Which of the following is an accidental parasite of humans?

A) Entamoeba histolytica
B) Acanthamoeba
C) Plasmodium
D) Balantidium coli
E) Ascaris lumbricoides

Question 50

Which of the following intestinal protozoa are considered parasites of humans only?

A) Entamoeba histolytica
B) Cyclospora cayentanensis
C) Balantidium coli
D) Giardia intestinalis
E) both Entamoeba histolytica and Cyclospora cayentanensis

Question 51

Because (cysts/cysticerci/larva) are readily visible in meat and give it a "mealy" look, inspection of meat can decrease chance of infection with Taenia.

Question 52

Because beavers are a common zoonotic source of infection with (Balantidium/Entamoeba/Giardia), the resulting condition is sometimes referred to as "beaver fever."

Question 53

Which of the following is the most important vector of human diseases?

A) mites
B) lice
C) fleas
D) mosquitoes
E) sand flies

Question 54

Acanthamoeba and (Entamoeba/Naegleria/Plasmodium) cause rare and usually fatal infections of the brain.

Question 55

Because Plasmodium (falciparum/malariae/ovale/vivax) requires Duffy antigens to attach to and infect erythrocytes, Duffy- negative individuals are immune to this parasite.

Question 56

Damage to the (brain/heart/liver) is the primary result of fetal infection with Toxoplasma gondii.

Question 57

The (cestodes/nematodes/trematodes) are helminths with an incomplete digestive system.

Question 58

Which of the following parasites is NOT generally microscopic in its mature form, even though microbiologists usually study them?

A) leishmanias
B) amoebae
C) cyclosporas
D) toxoplasmas
E) helminths

Question 59

The mildest type of malaria is caused by Plasmodium (falciparum/malariae/ovale/vivax).

Question 60

An intestinal parasite that is an emerging disease in North America, (Cryptosporidium/Cyclospora/Entamoeba) causes a watery diarrhea with fever.

Question 61

All nematodes are dioecious.

Question 62

Balantidium coli is the only ciliate known to cause disease in humans.

Question 63

Most diagnostic techniques are not very effective for Cryptosporidium.

Question 64

Visceral leishmaniasis is also known as kala- azar and is fatal in 95% of untreated cases.

Question 65

Compare and contrast infection with Taenia saginata and Echinococcus granulosus in humans, including the consequences of the infections.

Question 66

Why is self- reinfection commonly seen in children that suffer from pinworms?

Question 67

Parasitic diseases have been considered uncommon in developed countries but many are now emerging diseases in these parts of the world. Discuss factors that contribute to this shift.

Question 68

A hunter was camping with his dog near a mountain spring where beavers were building a dam. After a month, he developed severe watery diarrhea, abdominal pain, bloating, vomiting, and low- grade fever. His stool had a "rotten- egg" smell of hydrogen sulfide. What is the most likely parasite causing this patient's condition, and how is diagnosis confirmed?

Question 69

All tapeworms are intestinal parasites that completely lack digestive systems.

Question 70

All flukes are dioecious.

Question 71

Entamoeba histolytica can cause keratitis if it is introduced through an abrasion in the conjunctiva.

Question 72

How does the life cycle for the Trypanosoma that causes sleeping sickness differ from the one that causes Chagas' disease?

Question 73

Plasmodium reproduces by binary fission.

Question 74

Contact with infected cats and their feces is the only mode of transmission of Toxoplasma to humans.

Question 75

Anemia is a common consequence of hookworm infection.