chapter 23
Giardiasis is one of the more common GI diseases in the United States. Both animals and humans are at risk for developing this disease. In which of these cases would a human be most likely to become infected by this pathogen
A family hiking in the woods allows its dog to drink from a nearby stream. When they return home, the dog becomes sick with diarrhea in the house and family members must clean up the mess
Would a person living in Canada be able to contract malaria from a mosquito bite
A person living in Canada would not be likely to contract malaria from a mosquito bite because Plasmodium falciparum cannot complete its life cycle at a temperature below 20 degrees C
The tsetse fly is responsible for the spread of
African sleeping sickness
The largest nematode parasite of humans is
Ascaris lumbricoides
Triatoma, commonly called "kissing bugs," are vectors of
Chagas' disease
The protozoan (Cyclospora/Cryptosporidium/Echinococcus) can occasionally be transmitted from person to person
Cryptosporidium
Entamoeba histolytica can cause keratitis if it is introduced through an abrasion in the conjunctiva
False
Which species of Plasmodium typically causes the most serious disease
P. falciparum
Which of the following regarding all of the tapeworms that infect humans is TRUE
They all have non-human intermediate hosts
Anemia is a common consequence of hookworm infestation
True
Several species of Plasmodium cause malaria in humans
True
Once infected with Trypanosoma brucei, the patient's immune system cannot clear the infection and develop immunity because the parasite
changes its glycoprotein surface antigens every time it replicates
Balantidium coli uses ________ to penetrate the intestinal mucosa
cilia
Which of the following is correctly matched
definitive host: mature forms reproduce
The most severe form of malaria, called "blackwater fever" is caused by Plasmodium(falciparum/malariae/ovale/vivax)
falciparum
Trypanosoma cruzi is introduced into the body by
feces containing trypomastigotes contaminating a bite wound
The primary risk to humans infected with Echinococcus granulosus is
formation of hydatid cysts.
The helminth parasite Schistosoma
has snails as intermediate hosts
Cycles of fever which recur every 48 hours is characteristic of
malaria
A housefly can transmit diseases as a (biological/fomite/mechanical) vector
mechanical
In cestodes, gravid proglottids are found __________
near the end of the strobila
The protozoans known as apicomplexans
reproduce by schizogony and are intracellular parasites.
Apicomplexans reproduce asexually by (mitosis/schizogony/fission
schizogony
The easiest way to prevent Taenia infection in humans is to
thoroughly cook or freeze meat
The ________ stage of a protozoan is the actively feeding and reproducing stage
trophozoite
Which of the following is an accidental parasite of humans
Acanthamoeba
Corneal replacement is sometimes necessary as a result of which of the following diseases
Acanthamoeba keratitis
Blood smears are used in diagnosis of
African sleeping sickness and malaria
Which of the following helminth parasites do humans acquire by eating undercooked saltwater fish
Anisakis
Which of the following is a ciliated pathogen of the intestinal tract
Balantidium
Humans are the only reservoir for (Balantidium/Entamoeba/Giardia), an intestinal parasite that causes diarrhea.
Entamoeba
Which of the following is transmitted by the fecal-oral route
Entamoeba histolytica
Which of the following is the most common parasitic worm in the United States
Enterobius vermicularis
Which of the following statements concerning infection with Toxoplasma gondii is FALSE
Even though it can be transmitted across the placenta, it is harmless to the fetus
All nematodes are acquired by ingestion
False
Contact with infected cats and their feces is the only mode of transmission of Toxoplasma to humans
False
Plasmodium reproduces by binary fission
False
The vectors of ________ are sand flies
Leishmaniasis
To diagnose giardiasis, microscopic evaluation is required and it is often hard to diagnose. Why do you think this is so?
Multiple stool samples are required to diagnose giardiasis because the cysts and trophozoites are shed only intermittently
Acanthamoeba and (Entamoeba/Naegleria/Plasmodium) cause rare and usually fatal infections of the brain
Naegleria
Which of the following organisms can colonize the nasal cavity and enter the brain to cause meningoencephalitis
Naegleria
There are four species of Plasmodium that cause the disease malaria, of which P. falciparum is the most virulent. P. falciparum is transmitted by a mosquito vector to a human host. Can all mosquitoes transmit malaria? Why or why not
Only female Anopheles mosquitoes can transmit the malarial parasite to a human host because they are the only ones who take a blood meal from the host
Why is snail fever a common name for infections with Schistosoma
Snails are the intermediate host
Which of the following phases of infection occurs in the mosquito
Sporogonic phase
A human fecal sample is examined and found to contain a few strobila. The person is probably infected with
Taenia
Malaria used to be endemic in the U.S., but has not been prevalent for decades. How is this possible
The U.S. initiated a mosquito eradication program
The main symptoms of malaria are cycles of fever, anemia, and fatigue. During which stage of malaria would these symptoms be most apparent
The erythrocytic phase of the life cycle is most likely to cause these symptoms
Which vector is required for the spread of malaria
The female Anopheles mosquito
In the life cycle of Giardia intestinalis, the small intestine plays a pivotal role. What is the importance of the small intestine in the development of giardiasis
The small intestine is where the Giardia cyst releases the trophozoite and it can adhere to the epithelial cells and begin to multiply
What is a characteristic shared by the protozoa which are intestinal parasites of humans
They have a dormant cyst stage
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
Trichomonas
Which of the following is the most common parasitic disease in industrialized nations
Trichomonas infection
The presence of active motile multi-flagellated trophozoites in vaginal or urethral secretion is indicative of infection with
Trichomonas vaginalis
All tapeworms are intestinal parasites that completely lack digestive systems
True
Balantidium coli is the only ciliate known to cause disease in humans
True
Herbivores are the normal hosts for Fasciola species
True
Humans can be accidental intermediate hosts for some tapeworms
True
Which of the following nematodes can be transmitted by mosquitoes
Wuchereria bancrofti
Which of the following groups of protozoan parasites is typically nonmotile
apicomplexans
The parasites classified as Nematodes
are known as roundworms
The most common nematode infection worldwide is (ascariasis/filariasis/pinworms
ascariasis
Diagnosis of malaria relies on identification of trophozoites in a __________
blood smear
Which of the following intestinal protozoa are considered parasites of humans only
both Entamoeba histolytica and Cyclospora cayentanensis
The definitive hosts for Echinococcus granulosus are
canines
The infectious stage of a beef tapeworm for humans is the
cysticerci in beef
Episodes of fever in a patient with malaria coincide with which of the following events
erythrocyte lysis
Elephantiasis is caused by
filarial roundworms
The only helminth disease of humans spread by an insect vector is
filariasis
Severe frothy diarrhea with a "rotten-egg" smell accompanied by abdominal pain, bloating, and fever are signs and symptoms consistent with
giardiasis
The (brain/heart/liver) is the organ most severely damaged by Trypanosoma cruzi
heart
Which of the following parasites is NOT generally microscopic in its mature form, even though microbiologists usually study them
helminths
Which of the following is the same for both Trypanosoma cruzi and Trypanosoma brucei
importance of early diagnosis and treatment
The number of cases of schistosomiasis has decreased over the past few decades due to which of the following
improvement in water systems
Humans become infected with Fasciola by
ingesting cysts on vegetation
Humans become infected with Toxoplasma gondii primarily by
ingesting meat containing the parasite
The (definitive/intermediate/primary) host is where immature stages of parasites develop
intermediate
All of the following diseases can be diagnosed from stool samples except__________
leishmaniasis
Which of the following arthropod vectors may spend its entire lifetime in association with a single individual
lice
The salivary glands of a tsetse fly will contain which of the following forms of Trypanosoma brucei
mature infective forms
Humans become infested with liver flukes by ingesting the (cercaria/metacercaria/miricidium) stage of the worm
metacercaria
The ________ spreads more parasitic diseases to humans than any other vector
mosquito
Which of the following is the most important arthropod vector of human diseases
mosquitoes
Eating undercooked (fish/pork/snails/vegetables) can result in infestation with Taenia solium
pork
Which of the following contributes to infection with Trichomonas vaginalis
preexisting disease (chlamydia, for example
The release of large quantities of merozoites into circulation at one time is due to a form of reproduction by Plasmodium known as __________
schizogony
The (proglottid/scolex/strobila) of an adult tapeworm is its anchor to the hosts intestine
scolex
Which of the following poses the greatest risk of contracting schistosomiasis
swimming in contaminated water
Which of the following phases of malaria occurs in humans
the erythrocytic cycle
The (cestodes/nematodes/trematodes) are helminths with an incomplete digestive system
trematodes
The _____ form of the parasite has a characteristic "ring" shape
trophozoite
Which of the following is necessary for successful xenodiagnosis of Chagas' disease
uninfected vectors
What method is the LEAST effective for controlling malaria
vaccination against P. falciparum
The protozoal disease known as (cutaneous/mucocutaneous/visceral) leishmaniasis is potentially fatal
visceral
Which type of leishmaniasis is most likely fatal
visceral leishmaniasis
The definitive host of a parasite is
where the mature form of the parasite occurs