Quiz 3 - Buxton - Parasites

Question 1

How are parasites transmitted?

Answer 1

Direct ingestion/Direct inoculation

By a vector

Question 2

What is a vector?

Answer 2

An organism that transmits an infectious agent from one host or reservoir to another
-Coincidental

Question 3

What is an intermediate host?

Answer 3

Host in which the asexual phase of a parasite occurs

-Essential part of the life cycle

Question 4

What is the definitive host?

Answer 4

Host in which the sexual phase of parasite occurs

-Essential part of the life cycle

Question 5

Where do parasites infect?

Answer 5

Intestinal
Urinary
Respiratory
Soft tissue
Blood
-Intra
-Extra
CNS

*And travel occurs

Question 6

What are protozoans, helminths, arthropods?

Answer 6

Protozoa - Unicellular

Helminths - Wormlike, differentiated tissues

Arthropods - Hard exoskeleton, jointed appendages

Question 7

Ascaris lumbricoides is what?

Answer 7

A nematode

• Largest and most common intestinal helminths**
• Looks like an earthworm
• Moist, tropical climates

Question 8

Enterobius vermicularis is what?

Answer 8

Nematodes - this is a pinworm

-Most common roundworm infection
-Very infectious - ingestion (diapers and sandboxes)
-Worm is small
—Male and female lie in cecum and mate
—Female migrates thru colon and out to perianal area at night to deposit eggs
—Eggs identified using scotch tape method

Symptoms: Perianal itching, secondary bacterial infection, eczema, irritability

Question 9

Hookworms are what?

Answer 9

Nematodes

Question 10

What is the structure of a cestode (tapeworm)?

Answer 10

Head or scolex

• Sucking discs for attachment
• Rostellum with hooks

Generative neck

Proglottids
-Self contained male and female parts

Question 11

What does gravid mean?

Answer 11

Egg producing

Question 12

What is Taenia solium?

Answer 12

Cestode - Pork tapeworm

Man ingests larvae that are in tissue of pig when he eats undercooked pork

Larvae go to jejunum

Mature worm attaches to intestinal wall and can live for years and up to 10 meters long

May encyst in the brain or other tissues

Symptoms include abdominal discomfort, nausea, weight loss, and diarrhea

*This is the one that you LEAST want

Question 13

Taenia saginata is what?

Answer 13

Beef tapeworm

Question 14

What is schistosoma haematobium?

Answer 14

Trematode

• Not found in US
• More than 200 million people infected
• Second only to malaria as the most devastating parasitic disease
• Spine on one end
• Acquire from swimming or wading in snail-infested fresh water

-Male is more flat-like and female is more worm like and the male wraps around the female

Question 15

Giardia is what?

Answer 15

Flagellate

• Foul smelling and foamy diarrhea, gas, pain, can lead to duodenal obstruction
• Transmitted in contaminated food and water
• Endemic in Uintas, beavers are primary reservoirs

Question 16

Trichomonas vaginalis is what?

Answer 16

Flagellate

• Sexually transmitted**
• NO CYST STAGE

Question 17

Trypanosoma sp. is what?

Answer 17

Flagellate

• Vector borne flagellates that live in blood
• African sleeping sickness

Question 18

Entamoeba histolytica is what?

Answer 18

Amoeba

-Distribution in areas of poor sanitation

• Transmitted via contaminated food and water
• May be sexually transmitted
• Bloody diarrhea***
• Can migrate to liver and brain
• May cause ulcers
• May be asymptomatic

Question 19

Cryptosporidium is what?

Answer 19

Sporozoa

• World-wide distribution in mammals
• Resists chlorine and ozone treatment
• Spread animal to animal, animal-human, human-human (fecal-oral or sexual contact)
• Some foodborne transmission in fruits and vegetables
• Anal sexual contact
• Gay men, animal handlers, Vets, and day care participants at increased risk

Question 20

Toxoplasma gondii is what?

Answer 20

Sporozoa

-Cat feces is usually the culprit
-Humans get it from undercooked meat or cat feces
—Sexual reproduction occurs in cat
-Can be passed from mother to child
—Severe pregnancy infections
—-Only small percent achieve recovery, 1st trimester infections usually cause still birth. Infections after 1st trimester include encephalitis, hydrocephalus, psychomotor, or mental retardation

Question 21

What are arthropods?

Answer 21

Usually act as vectors or intermediate hosts

-Insects
—Mosquitoes
—Fleas
—Lice
—Bugs
—Flies
—Ticks, mites, spiders
—Crustacea

Question 22

How is diagnostic testing done for parasites?

Answer 22

Based on patient history and travel

If no travel, ELISAs for Giardia, Cryptosporidium, and E. Histolytica

Question 23

What is a parasite?

Answer 23

An organism living in or on a host where the organism gains benefit at the expense of the host

Question 24

What is an endoparasite?

What is an ectoparasite?

Answer 24

Endo: Lives inside its host

Ecto: Lives on the outside of its host (Arthropod)

Question 25

Protozoa consist of what?

Answer 25

Amoeba

Flagellates

Sporozoa

Ciliates

Question 26

Helminths consist of what?

Answer 26

Nematodes (round worms)

Trematodes (flatworms/flukes)

Cestodes (Tapeworms)

Question 27

Arthropods consist of what?

Answer 27

Insects
-Mosquitoes, fleas, lice, flies

Ticks, mites, spiders

Crustacea

Question 28

Protozoa produce what?

Helminths and arthropods produce what?

Answer 28

Cysts

Eggs

Question 29

Roundworms (Nematodes)
Tapeworms (Cestodes)
Flukes (Trematodes)

Shape?

Repro?

Digestive tract?

Hosts?

Answer 29

Roundworms

• Spindle
• Separate sexes
• Tubular
• Variable

Tapeworms

• Head and proglottids
• Hermaphroditic
• None
• One

Flukes

• Mostly leaf-like with oral and ventral suckers
• Mostly hermaphroditic
• Blind
• Two

Question 30

What is paragonimus westermani?

Answer 30

TREMATODE - Lung Fluke

• Found in developing countries
• Humans ingest immature fluke in raw, pickled, or undercooked freshwater crabs or crayfish
• Goes to the lungs, chest pain

Question 31

Protozoa -

Organelles of locomotion
Reproduction of the following:

Rhizopods (Amoeba)

Ciliates

Flagellates

Sporozoa

Answer 31

Rhizopods

• Pseudopods
• Binary Fission

Ciliates

• Cilia
• Binary Fission

Flagellates

• Flagella
• Binary Fission

Sporozoa

• None, some flagella
• Schizogony/Sporogony (sexual/complex)