Apr30 M1-Nematodes Flashcards
3 categories of helminths (worms. pluricellular parasites)
nematodes (roundworms), cestodes and trematodes
5 intestinal nematodes (roundworms)
- strongyloides
- ascaris
- trichuris
- hookworms (ancylostoma and necator)
- enterobius
3 systemic nematodes (roundworms)
- trichinella
- toxocara
- filaria (lymphatic, loa loa, onchocerca)
how a parasitic nematode infection is diagnosed normally
microscopy/detection of eggs in the stool (the parasite stays in the intestines)
trichuris trichiura mode of transmission and what is transmitted
fecal-oral
the eggs are what is transmitted
trichuris trichiura where the parasite lives
in the colon
trichuris trichiura (whipworm) clinical presentation in individual with low burden of infection (Canada or immigrant living in Canada)
asymptomatic, no eosinophilia
trichuris trichiura (whipworm) clinical presentation in individual with high burden of infection (tropics, worm load dependent)
- dystentery
- prolapsed rectum
- iron deficiency anemia
- clubbing (hypertrophic osteoarthropathy)
trichuris trichiura (whipworm) life cycle (linked to transmission) + reservoir
- lives in humans only (fecal-oral between humans)
- main transmission is human feces used as fertilizer and then it gets in food
enterobius vermicularis (pinworm) mode of transmission
fecal-oral (it helps that the mom worm living in the distal colon lays eggs around the anus at night so you’ll scratch and spread them everywhere)
who gets enterobius vermicularis (pinworm) infections particularly
children
enterobius vermicularis (pinworm) clinical pres low burden (Canada)
- asymptomatic
- perianal itch
- recurrent UTIs (female children)
enterobius vermicularis (pinworm) clinical pres high burden (tropics)
- asymptomatic
- perianal itch
- recurrent UTIs (female children) (same as low burden)
resistant worms definition
- doesn’t exist
- if you have a maintained infection with a worm that doesn’t live long, it means you have eggs in your environment (if worm lives 2-3 months, dies after that)
enterobius vermicularis (pinworm) transmission
same as whipworm, fecal-oral. eggs layed. ends up in someone’s mouth
ascaris lumbricoides (roundworm) transmission
fecal-oral
geohelminths definition
group of helminths with life cycle similar to ascaris, trichuris and enterobius and also called SOIL TRANSMITTED helminths (bc human feces in soil)
geohelminths (trichuris (whipworm), enterobius (pinworm), ascaris (roundworm), hookworms, etc.) common clinical association
- geohelminth triad
- associated with cognitive and growth development problems in children
ascaris lumbricoides (roundworm) clinical pres in low burden (Canada)
asymptomatic
ascaris lumbricoides (roundworm) clinical pres high burden (tropics)
- abdominal pain
- SI obstruction (lives in SI)
- biliary tree obstruction (if very heavy burden and crawled up)
- perforation of intestine suture
- malnutrition
- eosinophilia (if in its migratory phase)
how ascaris (roundworm) life cycle differs from trichuris (whipworm) and enterobius (pinworm)
when you swallow eggs (that an adult worm hatched in someone else’s SI), it goes in your SI, hatches (hatches = mot pour couver et éclore), bursts through intestinal mucosa and goes in portal circulation, liver, IVC, lungs, airways, pharynx, esophagus, back in SI and NOW adult (eosinophilia DURING this cycle only)
how ascaris (roundworm) dx differs slightly from trichuris (whipworm) and enterobius (pinworm) dx
for ascaris, you CAN pass WORMS in the stool and see them (not just eggs)
2 genera (pl. genus) of hookworms
- ancylostoma duodenale
- necator americans
hookworms (ancylostoma and necator) mode of transmission
- fecal-skin transmission (don’t step on poop). the LARVA gets through the skin
- contact with feces contaminated soil