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Flashcards in parasites Deck (51)
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1

all helminths are

animals --> metozoans (complex structure, multicellular, and eukaryotic)

2

helminths 2 phyla

playhelminths (cestodes and trematodes) and nematodes

cestodes are tapeworms
trematodes are flukes
nematodes are roundworms

3

true or false:
1. helminths live for years
2. helminths multiply within host

1 - true
2 - do NOT multiply in host (a few exceptions); need to leave body to continue lifecycles

4

fasciolopsis buski is a ...

trematode (fluke)

5

trematodes

flukes
flat, leaf shaped worms with 2 muscular suckers and a blind loop intestinal tract (regurgitates)
hermaphroditic (except scistosomes)
require intermediate host (snails/clams)

6

fasciolopsis buski

a trematode you acquire by eating encysted larva in aquatic vegetation (like water chestnuts)
develops in small intestine for 3 months --> eggs in stool
*can be asymptomatic OR diarrhea, fever, abd pain, ulcers, and hemorrhage
treat with praziquantel

7

what parasite encysts in water vegetation (water chestnuts/clams)?

fasciolopsis buski (a trematode)

8

cestodes

tapeworms
flat, ribbon like composed of proglottid segments which contain reproductive organs
have suckers with hooks on scolex (head) to attach to intestinal lining
has NO digestive tract -- food absorbed through soft body

9

which cestode does not have hooks to attach to intestines?

D. latum

10

which group contains the taenia?

cestodes

11

taenia lifecycle

cystic larvae in striated muscle of animals
cooking meat destroys the cysts so transmission occurs with undercooked meat
you have to ingest the EGGS fo rinfections; tapeworm itself is not infections so ingesting an adult just results in you passing eggs in stool which THEN are infectious for next victim

12

to be infected by taenia you have to ingest

the eggs

13

taenia solium

tapeworm acquired by eating larvae in pork
ingestion of larvae --> adult in intestines
ingestion of eggs in food/water/or self (hand to mouth) --> cysticercosis
after ingestion the oncosphere penetrates intestinal wall, circulates in tissues, and develops into a cysticercus (fluid filled bladder containing the scolex of larval form --> usually head to brain, muscle, and eyes
can cause neurocysticercosis

14

neurocysticercosis

taenia solium eggs were ingested and cysticersi implant in brain
presents with headache, seizure, deficit, death to hydrocephalus
single lesion can resemble cancer --> tissue biopsy is only sure diagnosis
treat with albendazole or praziquantel and corticosteroids

15

treat cestodes with

albendazole
praziquantel
+/- corticosteroids

16

taenia saginatum

a cestode (tapeworm)
acquire by eating larvae in undercooked beef; few symptoms; can grow to 10 m!!!

17

diphyllobathrium latum (d latum)

a cestode (tapeworm)
acquire by eating fish larvae
causes B12 deficiency

18

e granulosus

a cestode (tapeworm)
tiny tapeworm in dog bowel
larvae infect human if they ingest dog poop
worm doesnt grow in humans but can produce eggs/proglottids in stool

19

can you tell the difference between taenia eggs in feces?

no but you can tell difference between proglottid segments

20

nematodes

roundworms
nonsegmented smooth with tapered ends, nonpigmented, with flexible outer coatings (cuticle) and muscular layer underneath
has nervous, digestive, renal, and reproductive organs
under positive pressure (filled with fluid; pressure is >atm)
hydrostatic skeleton for shape and movement

21

3 ways to transmit nematode round worms

eating eggs in fecal contaminated food/water
direct penetration through skin
eating infected food

22

type of nematode that can cause death and mortality?

intestinal nematodes

23

intestinal nematodes cause

stunted growth, reduced, physical activity, lower cognitive performance and low school attendance in children

24

determinant of nematode symptoms is

the number of nematodes

25

three characteristics of pathogenic nematodes

Smooth borders, Even shapes with tapered ends, Not pigmented

26

nematode symptoms

 GI - Abdominal discomfort, Bloating, diarrhea, perianal itching, Malabsorption
 Pulmonary – Pneumonitis, Transient infiltrates – migrate through the lungs, wheeze
 Skin
• Cutaneous larva migrans  Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it
• Hives (both hookworm and Strongyloides)IgE reaction to the worm causes generalize allergic reaction when invading into mucosa
 Nutrition/Hematologic - Fatigue due to iron deficiency (hookworm), Vitamin A/Zinc deficiency, & Protein losses

27

cutaneous larva migrans

nematode Worms get lost and can’t penetrate the subcutaneous tissue so they just move around until they die or you treat it

28

helminths and poverty

a vicious cycle
 Anemia (esp. hookworm)  Reduced work output, Impaired cognitive ability, and Decreased school attendance
 This leads to… poverty – contributes to poor levels of sanitation/education and more helminth infections

29

 Strongyloides and Hookworm lifecycle?

SKIN --> LUNGS --> GUT

30

ascaris lifecycle?

gut --> liver --> lungs --> gut