Term
Which of the following is an accidental parasite of humans?
A) Ascaris lumbricoides
B) Acanthamoeba
C) Balantidium coli
D) Entamoeba histolytica
E) Plasmodium |
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Definition
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Term
Which of the following organisms causes meningoencephalitis?
A) Entamoeba histolytica
B) Acanthamoeba
C) Naegleria
D) Balantidium
E) Giardia |
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Definition
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Term
Which of the following is a ciliated pathogen?
A) Balantidium
B) Plasmodium
C) Trypanosoma
D) Leishmania
E) Giardia |
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Definition
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Term
Once infected with Trypanosoma brucei, the patient cannot ever clear the infection and become immune because the parasite
A) has flagella that allow it to travel all over the body.
B) matures into infectious trypomastigotes.
C) reproduces by binary fission.
D) changes its glycoprotein surface antigens every time it replicates.
E) invades the central nervous system |
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Definition
| D) changes its glycoprotein surface antigens every time it replicates. |
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Term
Trypanosoma cruzi is introduced into the body by
A) feces containing trypomastigotes contaminating a bite wound.
B) the bite of a tsetse fly, which introduces the trypomastigotes into the body.
C) ingesting food contaminated with the parasite.
D) the bite of a sand fly that has ingested phagocytes containing the parasite.
E) wearing contact lenses cleaned with contaminated tap water. |
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Definition
| A) feces containing trypomastigotes contaminating a bite wound. |
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Term
Which form of Leishmania lacks flagella and multiplies in a mammalian host's macrophages?
A) promastigotes
B) amastigotes
C) the cystic form
D) the trophozoites
E) the epimastigote |
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Definition
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Term
Which of the following is the same for both Trypanosoma cruzi and Trypanosoma brucei?
A) central nervous system infection
B) where the protozoan matures in the vector
C) type of arthropod vector
D) importance of early diagnosis and treatment
E) means of entry into the host |
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Definition
| D) importance of early diagnosis and treatment |
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Term
Which of the following is the most common parasitic disease in industrialized nations?
A) giardiasis
B) Trichomonas infection
C) schistosomiasis
D) toxoplasmosis
E) balantidiasis |
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Definition
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Term
The presence of active motile multiflagellated trophozoites in vaginal or urethral secretion is indicative of infection with
A) Trichomonas vaginalis.
B) Chlamydia trachomatis.
C) Giardia intestinalis.
D) Acanthamoeba.
E) Balantidium coli. |
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Definition
| A) Trichomonas vaginalis. |
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Term
The protozoans known as apicomplexans
A) are motile.
B) reproduce by schizogony.
C) are intracellular parasites.
D) are motile intracellular parasites.
E) reproduce by schizogony and are intracellular parasites. |
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Definition
| E) reproduce by schizogony and are intracellular parasites. |
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Term
Severe watery diarrhea with a "rotten-egg" smell accompanied by abdominal pain, bloating, and fever are signs and symptoms consistent with
A) balantidiasis.
B) Chagas' disease.
C) cryptosporidiosis.
D) giardiasis.
E) leishmaniasis. |
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Definition
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Term
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 |
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Definition
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Term
Which of the following parasitic infections can be diagnosed using a blood smear?
A) African sleeping sickness
B) toxoplasmosis
C) malaria
D) African sleeping sickness and malaria
E) toxoplasmosis and malaria |
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Definition
| D) African sleeping sickness and malaria |
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Term
What is a prophylactic drug of choice for malaria?
A) tetracycline
B) proguanil
C) pyrimethamine
D) nifurtimox
E) artemisinin |
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Definition
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Term
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) It is typically contracted by eating undercooked meat.
C) Even though it can be transmitted across the placenta, it is harmless to the fetus.
D) The majority of infected people are asymptomatic.
E) It usually results in no permanent damage and is self-limiting. |
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Definition
| C) Even though it can be transmitted across the placenta, it is harmless to the fetus |
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Term
Which of the following parasites is NOT generally microscopic in its mature form, even though microbiologists usually study them?
A) amoebae
B) toxoplasmas
C) helminths
D) leishmanias
E) cyclosporas |
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Definition
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Term
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) leishmaniasis
C) Chagas' disease
D) giardiasis
E) balantidiasis |
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Definition
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Term
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) Acanthamoeba
B) Cryptosporidium parvum
C) Entamoeba histolytica
D) Toxoplasma gondii
E) Trypanosoma cruzi |
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Definition
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Term
The infectious stage of a beef tapeworm in humans is
A) the gravid proglottids.
B) the eggs.
C) the larvae.
D) the cysticerci.
E) the mature worm. |
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Definition
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Term
Differentiation between infection with Taenia saginata and with Taenia solium is carried out by examination of the
A) scoleces.
B) cysticerci.
C) proglottids.
D) eggs.
E) larvae. |
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Definition
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Term
The easiest way to prevent Taenia infection in humans is to
A) vaccinate cows and pigs.
B) vaccinate humans who are in contact with cows and pigs.
C) spray pastures and grazing lands with toxins that kill the parasite.
D) thoroughly cook or freeze meat.
E) identify patients with cysticerci in their muscles. |
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Definition
| D) thoroughly cook or freeze meat. |
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Term
A human fecal sample is examined and found to contain a few strobila. The person is probably infected with
A) Echinococcus granulosus.
B) Giardia intestinalis.
C) Taenia.
D) Schistosoma.
E) Necator americanus. |
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Definition
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Term
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) Ancylostoma duodenale.
B) Enterobius vermicularis.
C) Echinococcus granulosus.
D) Schistosoma mansoni.
E) Taenia solium. |
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Definition
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Term
How are the different types of Schistosoma identified?
A) by the location of the swimmer's itch they cause
B) by the lesion they cause
C) by the position of their spine and the shape of their eggs
D) by their intermediate host
E) by the treatments they respond to |
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Definition
| C) by the position of their spine and the shape of their eggs |
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Term
Which of the following nematodes can be transmitted by mosquitoes?
A) Wuchereria bancrofti
B) Ascaris lumbricoides
C) Ancylostoma duodenale
D) Necator americanus
E) Enterobius vermicularis |
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Definition
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Term
Which of the following is the most common parasitic worm in the United States?
A) Taenia saginata
B) Echinococcus granulosus
C) Schistosoma mansoni
D) Enterobius vermicularis
E) Ascaris lumbricoides |
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Definition
| D) Enterobius vermicularis |
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Term
Schistosoma
A) is a cestode.
B) uses snails as an intermediate host.
C) has proglottids.
D) is a roundworm.
E) is a liver fluke. |
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Definition
| B) uses snails as an intermediate host. |
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Term
Which of the following parasites infects the lymphatic system?
A) Schistosoma
B) Fasciola
C) Echinococcus
D) Wuchereria
E) Ascaris |
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Definition
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Term
Nematodes
A) are known as flukes.
B) are known as roundworms.
C) have males of the species larger than females of the species.
D) do not have a digestive system.
E) are all monoecious. |
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Definition
| B) are known as roundworms. |
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Term
Humans become infected with Fasciola by
A) ingesting the encysted metacercariae on watercress or other vegetation.
B) consuming cysticerci in contaminated meat.
C) ingesting water contaminated with eggs shed in infected dog's urine.
D) the penetration of cercariae through the skin.
E) the bite of infected mosquitoes. |
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Definition
| A) ingesting the encysted metacercariae on watercress or other vegetation. |
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Term
Elephantiasis is caused by
A) blood flukes.
B) liver flukes.
C) filarial roundworms.
D) tapeworms.
E) flatworms. |
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Definition
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Term
Which of the following vectors may spend their entire life associated with a single host individual?
A) ticks
B) mites
C) spiders
D) lice
E) fleas |
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Definition
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Term
Which of the following is the most important vector of human diseases?
A) mosquitoes
B) mites
C) fleas
D) sand flies
E) lice |
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Definition
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Term
Which of the following is transmitted by the fecal-oral route?
A) Entamoeba histolytica
B) Plasmodium
C) Schistosoma
D) Trichomonas
E) Schistosoma and Trichomonas |
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Definition
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Term
What do Echinococcus granulosus, Entamoeba histolytica, and Enterobius vermicularis have in common?
A) They are transmitted by insect vectors.
B) They live in the intestines of their definitive host.
C) They are intracellular parasites.
D) They cause zoonoses in humans.
E) They are diagnosed by examination of a blood smear. |
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Definition
| B) They live in the intestines of their definitive host. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| African sleeping sickness |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| Sexually transmitted disease |
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Term
| Balantidium coli is the only ciliate known to cause disease in man. True/False |
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Definition
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Term
| Contact with infected cats and their feces is the only mode of transmission of Toxoplasma to humans. True/False |
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Definition
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Term
| All tapeworms are intestinal parasites that completely lack digestive systems. True/False |
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Definition
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Term
| All flukes are dioecious. True/False |
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Definition
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Term
| Plasmodium reproduces by binary fission. True/False |
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Definition
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Term
| Ascariasis is the most common nematode infection worldwide. True/False |
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Definition
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Term
| Entamoeba histolytica can cause keratitis if it is introduced through an abrasion in the conjunctiva. True/False |
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Definition
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Term
| Anemia is a common consequence of hookworm infection. True/False |
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Definition
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Term
| Visceral leishmaniasis is also known as kala-azar and is fatal in 95% of untreated cases. True/False |
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Definition
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Term
| Most diagnostic techniques are not very sensitive for Cryptosporidium. True/False |
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Definition
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Term
| The feeding and reproducing stage of many protozoa is known as a ________. |
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Definition
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Term
| Acanthamoeba and ________ cause rare and usually fatal infections of the brain. |
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Definition
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Term
| With each wave of replication, ________ changes its glycoprotein surface antigens. |
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Definition
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Term
| The ________ is where immature stages of parasites develop. |
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Definition
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Term
| Because beavers are a common zoonotic source of infection with ________, the resulting condition is sometimes referred to as "beaver fever." |
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Definition
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Term
| ________ is an obligately parasitic protozoan that is incapable of surviving long outside the human host and is transmitted almost exclusively via sex. |
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Definition
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Term
| The mildest type of malaria is caused by ________. |
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Definition
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Term
| Because ________ requires Duffy antigens to attach to and infect erythrocytes, Duffy-negative individuals are immune to this parasite. |
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Definition
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Term
| Apicomplexans reproduce by ________. |
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Definition
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Term
| Microcephaly can result in a fetus infected transplacentally with ________. |
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Definition
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Term
| High worm burden with ________ may result in intestinal obstruction. |
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Definition
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Term
| The ________ are helminths with an incomplete digestive system. |
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Definition
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Term
| The tapeworm's ________ reflects a sequence of development. |
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Definition
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Term
| Because ________ are readily visible in meat and give it a "mealy" look, inspection of meat can decrease chance of infection with Taenia. |
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Definition
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Term
| ________ are commonly known as pinworms because of the shape of the female's tail. |
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Definition
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Term
| Discuss some of the adaptations that produce some resistance to malaria in people whose ancestors lived in areas endemic for this disease. |
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Definition
| During evolution, some genetic traits developed in people who live in areas endemic for malaria that rendered these people resistant to infection with this disease. Some of these genetic traits are the sickle-cell trait, hemoglobin C, and deficiency of glucose 6-phosphate dehydrogenase, which make the environment of the erythrocytes less hospitable to the parasites. Another adaptation is the absence of Duffy antigens on erythrocytes, which prevents entry by Plasmodium vivax. |
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Term
| How does the life cycle for the Trypanosoma that causes sleeping sickness differ from the one that causes Chagas' disease? |
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Definition
| Sleeping sickness is caused by T. brucei, and Chagas' disease is caused by T. cruzi, which differ from each other in many ways. First, T. cruzi matures in the hindgut of the kissing bug, whereas T. brucei matures in the salivary gland of the tsetse fly. T. brucei is injected directly through the vector's bite, while T. cruzi enters the host when the vector's feces are rubbed into a bite wound. T. cruzi has an intracellular stage, whereas T. brucei does not. T. brucei remains in fluid compartments of the body (blood and cerebrospinal fluid), whereas T. cruzi penetrates tissues throughout the body, especially the cardiovascular system. |
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Term
| 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? |
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Definition
| This person is most likely suffering from giardiasis. Because beavers are common zoonotic sources of Giardia intestinalis, giardiasis is sometimes known as "beaver fever." Infection usually results from ingesting cysts in contaminated drinking water. Even if humans avoid drinking contaminated water, they usually do not prevent their dogs from drinking it. Therefore, it is usually just a matter of time before the dog passes the protozoa to its owner. Diagnosis is confirmed by the presence of flat, pear-shaped trophozoites seen in the stool under microscopic examination. |
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Term
| Why is self-reinfection commonly seen in children that suffer from pinworms? |
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Definition
| After mating in the colon, the female pinworm migrates at night to the anus. Here it deposits its eggs perianally. This causes the intense perianal itching that is characteristic of this infection. Scratching leaves eggs on the skin and under the fingernails; as a result, infected individuals may continuously reinfect themselves. This is especially common in children because they do not tend to practice handwashing. |
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Term
| Compare and contrast infection with Taenia saginata and Echinococcus granulosus in humans, including the consequences of the infections. |
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Definition
Both of these parasites are cestodes (tapeworms) that are acquired by ingestion. Humans are the definitive host for T. saginata and become infected when they consume undercooked beef containing the immature larvae in the form of cysticerci. The larvae emerge in the intestine, attach to the wall, begin feeding, and mature into self-fertilizing adults. The humans pass the eggs in their feces. Intestinal infection with the adult tapeworm may be asymptomatic, but patients may experience diarrhea, nausea, abdominal pain, and weight loss.
Humans are accidental intermediate hosts of E. granulosus, a parasite of canines. Humans become infected when they ingest the tapeworm eggs, which hatch in the intestine. The larvae then burrow out of the intestine and take up residence in a variety of organs ranging from the liver to the brain. The larvae of E. granulosus are capable of asexual reproduction in intermediate hosts, so the cysts established by the larvae continue to increase in size (and number of larvae) throughout the lifetime of the host. Eventually, the expanding cyst damages the organ in which it resides, and the condition may progress to organ failure. As a consequence, the human hosts experience a range of symptoms determined by the organ(s) being damaged (e.g., declining liver function to the point of failure or brain damage may mimic a tumor). Humans are considered dead-end hosts for E. granulosus because their flesh is rarely consumed by the definitive host. |
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