Microbio Week 7 - Worms & Flukes (Mini Exam) Flashcards
What is the 4th type of Nematode roundworm that is not part of the “Big 3”
Threadworm
Which roundworm has an important ability called “endogenous” or “auto-reinfection”?
Threadworm
What are 2 other major types of worms of sufficiently high interest?
Tapeworms
Flukes
Which of these are considered “parasites” in the field of infectious diseases?
A. protozoans
B. bacteria
C. some insects
D. A & C
E. all of the above
D. A & C
What causes more human disease than any other infection?
Worms and flukes (helminths)
Worms and flukes have variation on ___________ route of infection and mature in soil
fecal-oral
Which type of flukes have the highest mortality?
Tropical blood flukes
Why are worms and flukes difficult to assess?
Low CDC reportability
Track left by a hookworm in the human body, shows an immune response
Laval migrans
What are the most successful human parasites?
Nematodes
5 most common parasite infections worldwide
Common roundworm
Whipworm
Hookworm
Threadworm
Pinworm
Which parasite infection is the #1 most prevalent in the US?
Pinworm
What is the only host for the entire life cycle of a pinworm?
Humans
What is the size of pinworms?
Small (5-10 mm)
Enterobius vermicularis
Pinworm
How do pinworms lay eggs?
Female emerges from anus and lays them on skin at night and dies
What do pinworm eggs require in order to develop?
More oxygen
Where are pinworms more often found?
Urban areas
How are pinworm eggs ingested?
Fecal-oral
Surfaces (including clothes)
Swallowing dust containing eggs
Almost all children are infected by pinworms at some time between the ages of _____ - _____
2 - 10
T/F: Adult pinworm infections are typically symptomatic
FALSE; they are asymptomatic
What are the symptoms of a pinworm infection?
Intense itching of perianal area
How long does a pinworm infection take to resolve?
~6 weeks (but eggs are often re-ingested)
How can you diagnose pinworm infections?
Collect them from area using scotch tape
How can you prevent pinworm infections?
Hand washing
Vaseline to prevent eggs from getting O2
Pyrantel
What is the #1 most medically important helminth in the US and the world?
Common roundworm
Ascaris lumbricodes
Common roundworm
What is the only host for common roundworms?
Humans
What is the size of common roundworms?
Large (up to 30 cm)
Where are common roundworms most abundant?
Tropics (Asia especially)
What is required for development of common roundworm larvae within eggs?
Warm moist soil
How do common roundworms and hookworms move in the body?
“Lung migration”
What are common roundworm eggs resistant to?
Chemical inactivation
What are common roundworm eggs susceptible to?
Sunlight
How long must common roundworm eggs incubate in warm soil in order to become infectious?
Weeks
How long are common roundworm eggs viable?
Years
In regions that use human waste as fertilizer, common roundworm infections from consuming ____________ are very common
vegetables
Common roundworm larva inside eggs are ingested from _____________ _______
contaminated soil
Common roundworms hatch in the small intestine and larvae burrow through the wall. How are they carried to the lungs?
Blood
T/F: The initial migration of tiny larval common roundworms through the small intestine often does NOT cause major symptoms
True
The size of the adult common roundworm can result in blocking the ___________, or bile/other ducts, but only on high doses/burdens
intestine
What are the symptoms of common roundworm infection?
Insomnia
Malnutrition
How long does an untreated common roundworm infection last?
1-2 years, which is the life-span of the adult common roundworm
(unless reinfected)
Hookworm eggs and early stage larvae mature in the soil and give rise to a __________ larva that is able to penetrate the ________
motile; skin
Necator americanus
Hookworm
Hookworm eggs and early stage larvae mature in the _____ and give rise to a _______ larva that is able to penetrate the skin
soil; motile
What is the big advantage of hookworms?
They have motile larva!
(don’t have to rely on ingestion of the eggs)
Ancylostoma duodenale
“Old world” hookworm species
T/F: Hookworms are smaller than common roundworms
True
What is the size of hookworms?
0.1 cm
T/F: Hookworm infections are more often symptomatic
FALSE; they are usually asymptomatic
How do hookworms injure humans?
Attachment and sucking blood (anemia)
Do hookworms lead to physical damage?
NO, but they injure by attachment and sucking blood (anemia)
How long do hookworms live?
2-4 years
Where do hookworms mostly live?
Tropical regions
Hookworm eggs are resistant in the _______, which must be warm and moist to sustain them and larvae. However, both eggs and larvae are susceptible to _____________
soil; sunlight
Where do hookworm eggs hatch?
In soil
How long can developing hookworm larvae live without a host?
Several weeks
How can you get a hookworm infection in regions without indoor plumbing?
Walking in latrine areas
How do hookworm larvae get into the human body?
Through skin
What part of the body do hookworms typically enter through? What does this cause?
Foot
Causes intense itching (“ground itch”)
How do hookworms migrate through the body? Where do they reside? What do they feed on?
Blood system to lungs (lung migration)
Coughed upwards, then swallowed
Reside in small intestine
Attaches/feeds on blood
What do hookworms cause?
Anemia
Fatigue
Weight loss
What can hookworms cause as they migrate through the bronchial tree?
Wheezing
Pneumonia-like symptoms
Eosinophilia
What is the most common way to diagnose hookworms?
Appearance of eggs in stool on “O & P”
When can eggs be seen during a hookworm infection?
5-7 weeks after infection
(this is when larvae mature)
What is the treatment of hookworms?
Mebendazole
Name 3 ways to prevent hookworm infection
Improved sanitation (especially human waste)
Shoes
Vaccines
Trichurus trichuria
Whipworm
What is the size of whipworms?
Big (3-5 cm long)
T/F: Whipworms have lung migration
FALSE
Where does the whipworm thread it’s thin, coiled majority of the body (whip-like anterior) into?
Mucosa of the colon
What is the thin, coiled majority of the body (whip-like anterior) of the whipworm?
It’s esophagus
What is the widened, pinkish gray region of the whipworm?
It’s intestines and reproductive organs
How long do whipworms live?
4+ years
What type of weather do whipworms like?
Tropical
What areas are whipworms most frequent?
Areas where human waste is used as fertilizer or outdoor latrines are used
Whipworm infection is most prevalent among __________
children
How do whipworm eggs enter the body?
Ingested directly or in food
Where do whipworm eggs hatch?
Small intestine
Where do adult whipworms migrate and thread their anterior portion (whip-like end)?
Colon
Are whipworm infections frequently symptomatic or asymptomatic?
Asymptomatic
Severe whipworm infection may also present with what?
Rectal prolapse
What are some characteristics of whipworm infection, particularly in children?
Weight loss
Nutritional deficiencies
Anemia
What exam reveals the presence of typical whipworm eggs?
Stool O & P
What can be used to directly diagnose whipworms by ID of the threadlike form with an attenuated, whip-like end?
Colonoscopy
What do you use to treat whipworm infections?
Bendazole + ivermectin
Strongyloides stercoralis
Threadworm
Like the hookworm, threadworm larvae actively seek hosts and penetrate the ______
skin
Where do threadworms replicate?
-In the host
-Can also replicate WITHOUT a host in soil
(this is unique!)
The largest nematode parasite of humans is…
Common roundworm (Ascaris lumbricoides)
Which of the following is the most common parasitic worm in the United States?
Taenia saginata
Schistosoma mansoni
Ascaris lumbricoides
Echinococcus granulosus
Enterobius vermicularis
Enterobius vermicularis (pinworm)
The parasites classified as Nematodes are known as…
Roundworms
Which of the following regarding all of the tapeworms that infect humans is TRUE?
They all have non-human intermediate hosts.
They reside in the muscle tissue of the definitive host.
Humans are the normal intermediate hosts.
The larva can directly infect humans upon contact with skin.
They are transmitted by insect vectors.
They all have non-human intermediate hosts.
Why are many common helminth infections self-limited in duration?
effective treatments are available
immune responses usually clear the parasite
most prevalent worms do not replicate in the body
all of these
most prevalent worms do not replicate in the body
