Quiz 3 - Buxton - Parasites Flashcards
How are parasites transmitted?
Direct ingestion/Direct inoculation
By a vector
What is a vector?
An organism that transmits an infectious agent from one host or reservoir to another
-Coincidental
What is an intermediate host?
Host in which the asexual phase of a parasite occurs
-Essential part of the life cycle
What is the definitive host?
Host in which the sexual phase of parasite occurs
-Essential part of the life cycle
Where do parasites infect?
Intestinal Urinary Respiratory Soft tissue Blood -Intra -Extra CNS
*And travel occurs
What are protozoans, helminths, arthropods?
Protozoa - Unicellular
Helminths - Wormlike, differentiated tissues
Arthropods - Hard exoskeleton, jointed appendages
Ascaris lumbricoides is what?
A nematode
- Largest and most common intestinal helminths**
- Looks like an earthworm
- Moist, tropical climates
Enterobius vermicularis is what?
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
Hookworms are what?
Nematodes
What is the structure of a cestode (tapeworm)?
Head or scolex
- Sucking discs for attachment
- Rostellum with hooks
Generative neck
Proglottids
-Self contained male and female parts
What does gravid mean?
Egg producing
What is Taenia solium?
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
Taenia saginata is what?
Beef tapeworm
What is schistosoma haematobium?
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
Giardia is what?
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
Trichomonas vaginalis is what?
Flagellate
- Sexually transmitted**
- NO CYST STAGE
Trypanosoma sp. is what?
Flagellate
- Vector borne flagellates that live in blood
- African sleeping sickness
Entamoeba histolytica is what?
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
Cryptosporidium is what?
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
Toxoplasma gondii is what?
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
What are arthropods?
Usually act as vectors or intermediate hosts
-Insects —Mosquitoes —Fleas —Lice —Bugs —Flies —Ticks, mites, spiders —Crustacea
How is diagnostic testing done for parasites?
Based on patient history and travel
If no travel, ELISAs for Giardia, Cryptosporidium, and E. Histolytica
What is a parasite?
An organism living in or on a host where the organism gains benefit at the expense of the host
What is an endoparasite?
What is an ectoparasite?
Endo: Lives inside its host
Ecto: Lives on the outside of its host (Arthropod)
Protozoa consist of what?
Amoeba
Flagellates
Sporozoa
Ciliates
Helminths consist of what?
Nematodes (round worms)
Trematodes (flatworms/flukes)
Cestodes (Tapeworms)
Arthropods consist of what?
Insects
-Mosquitoes, fleas, lice, flies
Ticks, mites, spiders
Crustacea
Protozoa produce what?
Helminths and arthropods produce what?
Cysts
Eggs
Roundworms (Nematodes)
Tapeworms (Cestodes)
Flukes (Trematodes)
Shape?
Repro?
Digestive tract?
Hosts?
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
What is paragonimus westermani?
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
Protozoa -
Organelles of locomotion
Reproduction of the following:
Rhizopods (Amoeba)
Ciliates
Flagellates
Sporozoa
Rhizopods
- Pseudopods
- Binary Fission
Ciliates
- Cilia
- Binary Fission
Flagellates
- Flagella
- Binary Fission
Sporozoa
- None, some flagella
- Schizogony/Sporogony (sexual/complex)
