Helminths Flashcards
The pathology of helminth infections depends on _______________.
how many eggs you eat because helminths do not multiply inside you (except Stronyloides stercoralis)
How many people worldwide have a worm infection?
More than 1 billion (about 1/4 human beings)
Historically, helminth infections have been ignored because _______________.
there is usually no mortality; however, studies have shown that kids treated for worm infections have much better outcomes
Give a rundown on Ascaris lumbricoides.
- Infects people by fecal-oral ingestion of eggs (no red boots on Lumber Man)
- Can form pencil-thick worms up to one foot in the small intestine which can block the ileocecal valve (blocked tunnel)
- Eggs can survive for ten years in the soil
- Diagnosed by eggs in O&P
- Treated with albendazole
Describe Whipworm.
- Trichuriasis
- Infects large intestine
- Can cause bloody diarrhea from attachment site in mucosa
- Small worms (~ 1 inch)
- Can cause prolapsed rectum
Hookworms, Ascaris, and Strongyloides typically infect the _______________. Whipworm typically infects the ___________.
small intestine; large intestine
Infection with thousands of _________________ can lead to anemia because they suck blood.
hookworms (Ancylostoma duodenale and Necator americanus)
Why was hookworm common in miners?
Miners would poop in mines and the worms would get on other people’s hands and feet.
Describe the pathophysiology of lymphatic filariasis.
Also called elephantiasis, lymphatic filariasis is caused by Wuchereria bancrofti. This organism forms microfilaria in the lymphatics that damages lymph drainage.
_____________ is one of the leading causes of blindness worldwide.
Onchocerciasis
300,000 people blind worldwide
Unlike the worms, the __________ stage of Onchocerca causes damage.
larval
True or false: one infection with Onchocerca volvulus can ultimately lead to blindness.
False. Typically, blindness is only caused by repeated infection.
Describe Trichinella.
- Common in uncooked pork
- Larva can reinfect people (like Strongyloids)
- Ultimately infect muscles and forms cysts, leading to myalgia
Explain the “aircraft carrier in a bathtub” analogy.
Schistosoma are relatively large (up to 1 cm) and yet infect the blood vessels, which are small.
The _______________ form of Schistosoma infect snails.
larval
S. haemotobium lives in the ______________.
mesenteric veins of the bladder
What causes the pathogenesis in Schistosomiasis?
Egg deposition leading to tissue damage
Describe Taenia saginata and Taenia solium.
• T. saginata:
- From uncooked beef (cow beneath sagging tent)
•T. solium:
- From uncooked pork (pig beneath tent with the sun on it)
- Has mouth hooks (like the hooks on the tent)
Taenia, even large ones, are relatively ____________.
asymptomatic
Which life stage of Taenia causes problems in humans?
Larval stage (which can seed the brain)
What is the name of the cestode species that causes hydatid cysts?
Echinococcus
Describe the tapeworm that is transmitted by uncooked fish.
- Diphyllobothrium latum (guy DYing to get to the BaTHRooM)
- Longest tapeworm (like the long piece of toilet paper)
- Treated with niclosamide and praziquantel (nickel bathroom and guy eating pretzel)
- Can cause B12 deficiency (like the “you must B 12 to buy fireworks” sign)
What is the most common helminth infection worldwide?
Ascaris
Give a geographic rundown on the most common helminths by area.
- Border region: Echinococcus
- Appalachia: Ascaris and Strongyloides
- Mississipi delta: Toxocara and Ascaris
- Rural and tribal areas: Trichinella and Echinococcus
- Eskimos: Trichinella
Only the __________ Ascaris eggs are infective.
fertilized
How do people get infected with Tricuris?
Ingestion of embryonated eggs
Which helminth can alternate as a parasite or free-living organism?
Strongyloides
What’s the big difference between the life cycles of Strongyloides and Necator?
The eggs of Strongyloides hatch in the intestine, while those of Necator hatch in the feces.
A curious feature of Strongyloides is that _____________ are never seen in the host.
males
_______________ can be fatal in immunosuppressed people, so it is important to diagnose and treat these cases.
Strongyloides stercoralis
River blindness is caused by what organism?
Onchocerca volvulus
The ___________ of Onchocera cause the symptoms.
larvae
The “cysts” in Trichinosis are actually ______________.
encrusted larvae secreted from the adults in the small intestine
Why does Dracunculus emerge from the skin?
It drops its eggs into water to be eaten by another copepod.
Who helped eradicate Guinea worm?
Jimmy Carter
In 1982, there were 3.5 million cases per year. After long-term water education and filtration, this has been reduced to less than 25 last year.
How do snails get infected with Schistosoma?
The miracidia form penetrates snail tissue.
Once infected in a human, how do Schistosoma get eggs back into the environment?
By laying eggs in the circulation that pass to the liver and get excreted in bile
S. japonicum lodges in the mesenteric veins of the ______________, while S. mansoni lodges in the mesenteric veins of the ___________.
large intestine; small intestine
Japonicum is a larger word than mansoni.
Humans get infected with Taenia by ingesting cysts. Pigs and cows get infected by ingesting ___________.
eggs
Which is larger, T. saginata of T. solium?
T. saginata
Cysticercosis only occurs with T. ___________.
solium (which is why the pig is closer to the carousel)
Neurocysticercosis only occurs from ingested __________.
embryonated eggs
What pathology leads to the effects of Schistosoma?
Granulomas in the liver
Tapeworms are often _____________.
asymptomatic
Hydatid cysts can also appear in the _____________.
brain or lungs
