Helminths/worms

Question 1

what is a symbiont, commensal, parasite? define each.

Answer 1

Symbiont: mutual advantage
Commensal: no harm/no good
Parasite: thrives by doing harm

Question 2

eosinophilia suggests what kind of infection?

Answer 2

allergic OR parasite (usually a helminth)

Question 3

many helminths are ____, with lifespans that last _______

Answer 3

Many helminths are long-lived, with life spans that last decades

Question 4

Absence of eosinophilia does not exclude _______

Answer 4

infection with parasite

Question 5

what patient population gets pinworms?

Answer 5

Common helminthic infection in children

All social strata, all countries

Question 6

what is the most prevalent worm infection in the US?

Answer 6

pinworms “threadworms”

Question 7

hosts for pinworms?

Answer 7

only humans

Question 8

pinworm: where do they live in the body and what is the process for this?

Answer 8

Normal habitat: lumen of the cecum

Gravid female migrates to perineal area during the evening, deposits eggs (thousands) in folds of perineal skin
-Contamination of bedding, etc., scratching, hand-to-mouth –> eggs ingested and migrate to cecum

Question 9

cycle for pinworm: ___ to ____ days.

Answer 9

15-28 days

Question 10

Pruritus ani, especially in children, at night… what do you think they have?

Answer 10

pinworms

Question 11

Dx of pinworms

Answer 11

Scotch tape test, repeated

Visual inspection

Question 12

severity of pinworm infection depends on what? is there eosinophilia with this infection?

Answer 12

Severity of infection depends on number of days out of six scotch tape test positive
-usually no eosinophilia

Question 13

Txt for pinworms: hygiene and meds

Answer 13

Hygiene: wash hands, trim nails, wash bedding

Vermox® (mebendazole) 100 mg po stat repeat at 2 (and 4) weeks

Question 14

why do you need to repeat vermox for pinworms at 2 and 4 weeks?

Answer 14

it doesn’t kill eggs, so you kill with drug when new eggs hatch

Question 15

what is the most common parasitic disease in the world?

Answer 15

Ascariasis (round worm)

Question 16

life cycle of ascariasis/round worm/nematodes

Answer 16

eggs passed in feces, where they can remain in the soil for 2-3 years.

Eggs are ingested and hatch; larvae penetrate the intestinal wall, the heart wall to the lungs, lymphatics, bloodstream.
They travel to lungs where they mature.
worms go to small bowel and grow to adult/reproductive age

Question 17

physical length and lifetime length of ascariasis

Answer 17

Adult worms are 20-30 cm long, live for a year

Question 18

4 symptoms for ascariasis. What may the people see

Answer 18

worms from mouth or anus

can cause obstruction, cough, stomach pain, malnutrition

Question 19

Dx for Ascariasis

Answer 19

Fecal smear/ Ova and parasites

Question 20

What drug txt do you us for ascariasis, when do you recheck? why?

Answer 20

Mebendazole (Vermox)

recheck stools in 2 weeks to make sure they are gone

Question 21

rare complications from ascariasis

Answer 21

bowel obstruction
perforation and peritonitis
abscess

Question 22

how does one get tapeworm/cestodes ?

Answer 22

Person eats contaminated food- undercooked beef or pork meat- and gets infected

Question 23

what is unique about the tapeworm lifecycle?

Answer 23

lies dormant in the beef or pork muscle (in cysterici), then when ingested by person, they mature, then eggs or proglottids passed in feces.
* if a person ingested just the eggs, they will not get the infections because the worm needs the pork/beef for part of its lifecycle.

Question 24

tapeworms. there are usually how many? any symptoms?

Answer 24

Usually only one tapeworm

Usually asymptomatic

Question 25

txt for tapeworms

Answer 25

Appropriate drug followed by laxative (laxative b/c the hooks hold on very tight and you need to flush out proglottids (segments) and eggs)

Question 26

what is cystircercosis ?

Answer 26

Infx caused by eating eggs of pork tapeworm from infected feces.

Question 27

what do the larval tapeworms of cystircercosis do in the human? where in the body do they localize?

Answer 27

Host is “supposed to be” the pig, so larvae are at a dead end, just hang out, take up space.
**usually localize to the CNS

Question 28

a recent immigrant with new onset seizures, what do you think it might be?

Answer 28

Cysticercosis

Question 29

what does “symptoms secondary to mass effect” mean?

Answer 29

for cystercercosis- larva take up space in the brain (expanding mass) and symptoms are from this- HA, seizure,etc.

Question 30

why is the txt for cysticercosis controversial?

Answer 30

treatment can cause inflammation and swelling in brain (leading herniation and death). if you treat- you need to give steroids as well to deal with the subsequent inflammation

leave them alone if you can (b/c larva wont grow )

only treat if seizures are bad, weight cost and benefit

Question 31

what is the most common protozoa associated with intestinal human illness? what kind of protozoa is it?

Answer 31

Giardia (a flagellate)

Question 32

what is the most virulent kind of protazoa ameba?

Answer 32

Entamoeba histolytica (“breaks tissues”)

Question 33

usual symptoms of entamoeba histolytica

Answer 33

Typically get colitis symptoms

mucous diarrhea

Question 34

Dx to E. histolytica

Answer 34

Microscopy: ID parasite in stool: O & P X 3
Serology: antibodies positive only for histolytica
Colonoscopy

Question 35

Txt for E histolytica? what must you do after treatment?

Answer 35

Metronidazole (Flagyl): 750 mg po tid x 7-10 days

Test of cure after Tx

Question 36

epidemiology for giardia: wary of locations with _____ ______. how is it transmitted?

Answer 36

poor sanitation. transmission if person-to-person and through food/water

Question 37

Dx and Treatment for giardia?

Answer 37

Dx: Stool O and P x 3
txt: flagyl 250 mg TID (5-7d)

Question 38

3 major points for summary of this unit

Answer 38

Wash your hands! Boil water or use a filter.
Remember to get a travel history
Have a high index of suspicion with immigrants and travelers

Question 39

s/s for giardia

Answer 39

most are ASYMPTOMATIC

• malabsorption: steatorrhea/foul
• sudden diarrhea