HW ch 23 Parasites of Medical Importance

Please select all of the correct statements exhibited by the pathogenic amoebas.

- Naegleria causes damage to the brain, whereas Entamoeba does not - The death rate for amoebic diseases varies, depending on the type of amoeba causing the disease as well as the condition of the host - Amoebic diseases caused by Entamoeba histolytica, Ancanthamoeba, and Naegleria can be found in North America

Which groups of protozoa are typically nonmotile?

- Ciliates - Flagellates - Apicomplexans

Please select all of the organisms on this list that belong to the protozoan class of apicomplexans.

- Cyclospora - Cryptosporidium - Toxoplasma - Plasmodium

A patient is referred to you for diagnosis of an apicomplexan infection. The patient follows a strict vegan diet and spends her spare time hiking and mountain biking. Which organisms do you suspect?

- Cystoisospora - Cyclospora - Bebesia

Please choose all correct statements that describe nematode infections.

- Strongyloides is a roundworm - Species of dog hookworms can be transmitted to humans - Trichinella larvae encyst within skeletal muscle, causing muscle pain - The hookworm Necator can produce anemia in the affected individual because of the blood loss from the intestinal wall

Please choose the correct statement describing what sleeping sickness, Chagas' disease, and leishmaniasis have in common.

All of the infectious agents causing these diseases have an insect vector

Please choose the correct statement that explains the importance of cysts to the spread of Giardia intestinalis.

All of these choices are correct

Please match the arthropod to the disease it transmits. 1. fleas 2. biting bugs 3. Tsetse fly 4. lice 5. mosquitoes 6. hard ticks

Match each of the options above to the items below. 1. Bubonic plague 2. Chagas disease 3. African trypanosomiasis 4. Epidemic typhus 5. Dengue fever 6. Rocky Mountain spotted fever

Match each term with its correct answer. 1. Proglottid 2. Taenia saginata 3. Scolex 4. Taenia solium 5. cysticercus

Match each of the options above to the items below. 1. Site of reproductive organs 2. Beef tapeworm 3. Used for attachment to the intestinal wall in Taenia spp 4. Pork tapeworm 5. Infective stage of Taenia spp.

Please choose the type of sleeping sickness that affects the brain quickly and is more difficult to control due to the fact that its main hosts are large East African mammals

Rhodesian

A new protozoan species has been discovered that has a single long appendage emanating from the cell. Movement occurs when this appendage whips back and forth. This organism would be classified as

a flagellate.

Research into new drugs targeted against Taenia saginata and Taenia solium often focuses on the scolex of the worm as a potential target. This is because

the scolex is responsible for anchoring the worm within the intestine, and if the scolex is disabled, the worm would pass out of the body.

Unlike its relatives Sarcocystis, Isospora, and Cyclospora which are all transmitted through contaminated food and/or water, Babesia is transmitted by the bite of a __________.

tick

Elephantiasis occurs when small nematodes block the lymphatic ducts, preventing the return of lymph from the lower extremities and causing severe swelling of the lower extremities. Elephantiasis is caused by a

tissue nematode

The incidence of the disease _______ is very high in Alaska, due to the ingestion of contaminated bear and seal meat.

trichinellosis

An arthropod vector may be a required host of the microorganism in its life cycle; it may be a host in which the microorganism is reproducing until it gets to its next host; or it may just be the mechanical vector on which the microorganisms is riding.

true

Freezing for several hours is generally enough to kill Trichinella worms in wild bear meat.

true

Snails serve as an intermediate host for many flukes

true

When studying the four basic helminth life cycles, it is apparent that the egg larval stage of the worm has to be picked up by an intermediate host or develop in soil before it can infect humans.

true

An indication of helminth infestation is an increase in the number of __________ in the blood.

eosinophils

Humans are intermediate hosts for all trematode worms.

false

The elimination of malarial disease from countries where it used to be endemic (including the southeastern United States) occurred as a result of cheaper, nontoxic therapeutic drugs.

false

The long, thin structure of tapeworms allows them to remain unnoticed by cells of the immune system.

false

Tissue nematodes are generally acquired by consuming food or water contaminated with worms or their eggs.

FALSE

Please select all of the statements that describe the life cycle and infections of Toxoplasma gondii.

- The major host for this pathogen, where Toxoplasma's sexual reproduction occurs, is the dog. - Other incidental hosts, not necessary for this pathogen's life cycle, are birds, sheep, pigs, and cows - The transmission method is ingestion, either by contaminated food or picking up the oocysts on the hands - Infected pregnant women die from a fatal infection

You are a doctor checking over a patient in your office. The symptoms (and subsequent lab tests) all match elephantiasis, a lymphatic infection caused by worms and transmitted by a mosquito. This disease is not found in North America. Please choose the most likely explanation for this patient having this disease.

- The patient has a sister-in-law visiting them from a country that has elephantiasis - The patient has been on vacation to an area endemic for elephantiasis - The patient has been to a location with lots of mosquitoes

Please choose the correct explanation regarding these tapeworm dimensions—30 feet long, yet extremely thin.

- The thinness of the worms allows maximal absorption of nutrients - Their segments, called proglottids, are produced at the neck, adding length to the worm

The vectors responsible for the spread of filarial nematodes include

- black flies - mosquitoes

Which of the following correctly identify the three main categories of helminths?

- cestodes—tapeworms - trematodes—flukes - nematodes—roundworms - cestodes—apicomplexans - nematodes—flatworms

The risk of developing trichinellosis can be reduced by

- ensuring that pork has been fully cooked or fully frozen before eating - not eating wild bear meat

While examining a blood sample for the presence of Trypanosoma cruzi, you are able to distinguish an anterior flagellum but, because of the poor resolution of the microscope you are using, cannot tell if an undulating membrane is present or not. Which stages of the hemoflagellate may be present?

- promastigote - epimastigote - trypomastigote

The thick protective cyst of the Giardia flagellate is instrumental in the ability of the cell to

- survive for several weeks in the environment. - survive the acidic pH of the stomach. - survive in chlorinated drinking water.

Over the past fifty years the epidemiological pattern of parasitic disease in the United States has changed because

- widespread availability of air travel - increased numbers of people with compromised immune defenses - increased immigration between countries with high rates of parasitic infection and the United States

Please match the nematodes with their transmission method. 1. ingested eggs coming from contaminated soil 2. walking barefoot in contaminated soil 3. eating contaminated pork 4. transfer of eggs from anal area to mouth by fingers

1. Ascaris lumbricoides 2. Necator americanus 3. Trichinella spiralis 4. Enterobius vermicularum

Please match the disease with the correct description of its pathology. 1. Formation of large skin ulcer; chronic infection of skin and mucous membranes of the head can lead to severe disfigurement 2. Results in severe neurological deterioration, often leading to coma and death 3. The heart muscle and large intestine are primary targets; exhibit swelling of eye or mouth at entry site of agent (Romana's sign)

1. Leishmaniasis 2. African sleeping sickness 3. Chagas' disease

Please order the following events to test your understanding of the Plasmodium life cycle.

1. Mosquito transfers the sporozoite to human bloodstream. 2. The parasite moves into the liver cells. 3. The parasite infects red blood cells. 4. The male and female gametocytes of Plasmodium are produced. 5. Red blood cells rupture as parasite multiplies.

Please match the helminth with its major symptom to test your understanding of the tissue nematodes. 1. profoundly enlarged and inflamed legs and/or scrotum 2. transient nodules in skin and conjunctiva 3. blindness 4. highly irritating blisters on the feet or legs

1. Wuchereria bancrofti 2. Loa loa 3. Onchocerca volvulus 4. Dracunculus medinensis

Please order the following stages of hemoflagellate development, starting with the simplest stage.

1. amastigote 2. promastigote 3. epimastigote 4. trypomastigote

Please match the organisms with their portals of entry. 1. Entamoeba 2. Naegleria and Acanthamoeba

1. contaminated food or drinking water 2. contaminated swimming areas—lakes, ponds

Please match the organisms to the features that describe them. 1. flagellates 2. apicomplexa 3. amoeba 4. ciliates

1. have long, thin structures for motility 2. non-motile 3. use pseudopods 4. have hundreds or thousands of short, beating hair-like structures

Please match the disease with its transmission method. 1. Wuchereria bancrofti 2. Loa Loa 3. Onchocerca volvulus 4. Dracunculus medinsis

1. mosquito 2. Dipteran fly 3. black fly 4. drinking contaminated water

Please match the scientific name of the arthropod to its common name. 1. flea 2. tick 3. mosquito 4. body louse

1. xenopsylla 2. ixodes 3. aedes 4. pediculus

Efforts on farms to prevent pig feces from coming into contact with food or water are specifically meant to prevent the spread of

Balantidium coli

Tap water in some communities is exposed to ozonation and ultraviolet light specifically to destroy

Cryptosporidium

Outbreaks of Cryptosporidiosis have in the past been traced to domestic water supplies (tap water). Why is this?

Cysts of Cryptosporidium are able to survive the chlorination process usually employed to disinfect water

Naegleria fowleri would be most similar to

Entamoeba polyphaga.

Please choose the statement that describes the human host for the Necator hookworm.

Humans are a definitive host for Necator

Please choose the correct statement regarding Trichomonas vaginalis.

People often have more than one sexually transmitted disease, including that caused by Trichomonas vaginalis.

Please choose the explanation for why people who have had malaria cannot donate blood for the rest of their lifetime.

The malarial parasite can live in liver cells for dozens of years.

One of the most effective strategies used to prevent the spread of malaria is to have people sleep under mosquito nets in areas with large numbers of mosquitoes. Why isn't a similar strategy (the use of screens or mesh) emphasized as much during the waking hours?

The mosquito that spreads malaria feeds only at night.

Please choose the correct explanation as to why there are two variations of leishmaniasis.

The nature of the disease state is determined by the location of the infected macrophages harboring the protozoa.

Cryptosporidium is often associated with diarrheal outbreaks in the United States. Please choose the statement that explains why.

The oocysts formed by Cryptosporidium are extremely resistant to wastewater treatment.

In sleeping sickness and Chagas disease, humans are infected with which developmental stage of the hemoflagellate?

Trypomastigote

Most worm infections are identified by finding the parasites in the patient's specimen—blood, urine, feces—with a microscope and a slide. However, this is not so for the majority of bacterial, viral, and fungal infections. Please choose the statement which describes why this is so.

Worm eggs actually look very different from each other and are easily seen, even without oil immersion lens.

Tissue nematodes complete their life cycle in the__________, lymphatics, or skin.

blood

Please select the correct feature that is specific for Taenia solium, but not Taenia saginata.

can encyst within the brain

Please select the stage of Schistosoma that is released by infected snails.

cercaria

Please select the key symptom for malaria.

chills and fever

Outdoor interactive fountains are commonly linked to Giardia infection because

chlorine is ineffective at killing Giardia cysts

Balantidium coli is motile by means of

cilia.

Entamoeba histolytica exists within the small intestine as the feeding stage, the trophozoite. However, the infective stage of the amoeba is a(n) ________, which is dormant and highly resistant to dehydration as well as other adverse factors.

cyst

Infection with Entamoeaba histolytica ordinarily begins when

cysts are eaten

Malaria is mostly confined to a region around the equator known as the malaria belt because

mosquitoes are widespread in regions near the equator.

Activities that would reduce the risk of contracting Cyclosporiasis include

not eating raw food

Please choose the correct feature of Balantidium coli.

one of the only pathogenic ciliates to cause human disease

Excystation of Entamoeba histolytica occurs in the

small intestine

In Schistasoma, the development of a cercaria from a miracidium takes place in a

snail

Drainging swamps and marshland have been used to effectively combat malaria because

the mosquito that serves as a vector for the malarial parasite lays its eggs in these warm waters