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 are two other names for pinworms? (one common and one scientific)

Answer 5

threadworms, enterobius vermicularis

Question 6

what patient population gets pinworms?

Answer 6

Common helminthic infection in children

All social strata, all countries

Question 7

what is the most prevalent worm infection in the US?

Answer 7

pinworms

Question 8

hosts for pinworms?

Answer 8

only humans

Question 9

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

Answer 9

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 10

cycle for pinworm: ___ to ____ days.

Answer 10

15-28 days

Question 11

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

Answer 11

pinworms

Question 12

Dx of pinworms

Answer 12

Scotch tape test, repeated

Visual inspection

Question 13

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

Answer 13

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

Question 14

Txt for pinworms: hygiene and meds

Answer 14

Hygiene: wash hands, trim nails, wash bedding

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

Question 15

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

Answer 15

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

Question 16

When a (reliable) parent comes in and says that she saw worms in her kid’s stool, or crawling out of anus,is that evidence enough to treat for pinworms?

Answer 16

yes!

Question 17

what is the most common parasitic disease in the world? how many people are infected with this?

Answer 17

Ascariasis (round worm)

1 billion people

Question 18

life cycle of ascariasis/round worm/nematodes

Answer 18

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 19

physical length and lifetime length of ascariasis

Answer 19

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

Question 20

4 symptoms for ascariasis. What may the people see

Answer 20

worms from mouth or anus

can cause obstruction, cough, stomach pain, malnutrition

Question 21

Dx for Ascariasis

Answer 21

Fecal smear/ O &P

Question 22

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

Answer 22

Mebendazole (Vermox)

recheck stools in 2 weeks (b/c no resevoir for eggs for these)

Question 23

rare complications from ascariasis

Answer 23

bowel obstruction
perforation and peritonitis
abscess

Question 24

how does one get tapeworm/cestodes ?

Answer 24

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

Question 25

what is unique about the tapeworm lifecycle?

Answer 25

lies dormant in the beef or pork muscle (in cysterici), then when ingested by person were 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 26

tapeworms. there are usually how many? any symptoms?

Answer 26

Usually only one tapeworm

Usually asymptomatic

Question 27

txt for tapeworms

Answer 27

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 28

what is cystircercosis ?

Answer 28

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

Question 29

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

Answer 29

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

Question 30

what is the causitive agent for cysticerosis?

Answer 30

Larval stage of Taenia solium (pork tapeworm)

Question 31

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

Answer 31

Cysticercosis

Question 32

what does “symptoms secondary to mass effect” mean?

Answer 32

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

Question 33

why is the txt for cysticercosis controversial?

Answer 33

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 34

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

Answer 34

Giardia (a flagellate)

Question 35

what is the most virulent kind of protazoa ameba?

Answer 35

Entamoeba histolytica (“breaks tissues”)

Question 36

epidemiology of entamoeba histolytica: how many are infected worldwide?

Answer 36

50 million worldwide infected

Question 37

usual symptoms of entamoeba histolytica

Answer 37

Typically get colitis symptoms

“amebic dysentery”

Question 38

what is the non-pathogenic form of entamoeba histolytica? what is the difference between the two? (weeds maybe)

Answer 38

E. Dispar:

nonpathogenic form- looks the same (microscopically), but has no symptoms (usually)

Question 39

Dx to E. histolytica

Answer 39

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

Question 40

Txt for E histolytica? what is the cure rate? what must you do after treatment?

Answer 40

Metronidazole (Flagyl): 750 mg po tid x 7-10 days
90% cure rate
Test of cure after Tx

Question 41

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

Answer 41

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

Question 42

Dx and Treatment for giardia?

Answer 42

Dx: Stool O & P x 3
txt: metronidazole

Question 43

3 major points for summary of this unit

Answer 43

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