4/10 Parasitology and Travel Med I Flashcards Preview

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Flashcards in 4/10 Parasitology and Travel Med I Deck (45)
1

2 kinds of worms

  • Roundworms (intestinal and tissue)
  • Flatworms (tapeworms, flukes)

2

indication of worm infection?

eosinophilia 

3

T/F worms multiply in hosts

mostly false. most do not multiply in hosts

4

in worm infections, what is disease state determined by?

disease is determined by infecting numbers

5

general life-cycle of roundworm

  • All produce and release eggs; some eggs mature and are released as larvae
     
  • Do not multiply in host (must ingest more eggs in order to get more worms)

6

standard trmt of roundworms?

Bendazole – inhibits microtubule function, immobilizes and kills worms

7

What is this?

Pinworm

Enterobius vermicularis

8

What is this?

Pinworm

Enterobius vermicularis

9

What is the life cycle of the pinworm?

 

  • EGG ingestion --> intestines where larvae mature in into adults. Female pinworms migrate to anal verge to expel eggs via  feces
     
  • Eggs remain infectious in the environment for 2wks – requires repeated treatments

10

Where do pinworms occur?

Worldwide (
children (30%), adults (15%))

11

How are Enterobius vermicularis diagnosed? 

EGG, clear scotch tape prep from perianal area

12

Enterobius vermicularis treatment?

Bendazole - treat entire family for 2 weeks due to high recurrence of infection

13

Strongyloides stercoralis general life cycle?

  • LARVAE penetrates skin -> transported to the lungs where it penetrate alveolar spaces -> swallowed -> small intestines
     
  • Adult F deposit their eggs into the intestinal mucosa, from which larvae hatch and migrate to the lumen (no eggs in stool!!)
     
  • Larvae produced in small bowel can either be
    • passed into stool as the non-infectious form
    • become infectious and penetrate the intestinal mucosa, taking gram (-) bacteria with them, into the blood stream, resulting in a hyperinfection (+bacterial sepsis) where it goes on to reinfect the lungs, starting the cycle again 
       

14

How long can Strongyloides stercoralis last in the body? 

When is it usually reactivated?


Latent period (up to 30 years); can be reactivated by steroids -> hyperinfection

15

What is hyperfinection? What is it caused by?


Strongyloides stercoralis - occurs when it penetrates the intestinal mucosa, taking gram (-) bacteria with them, into the blood stream, resulting in a hyperinfection (+bacterial sepsis) where it goes on to reinfect the lungs, starting the cycle again  



 

16

Where is Strongyloides stercoralis found?

Worldwide - warm, moist climates

17

symptoms of Strongyloides stercoralis?

  • Asxs
  • GI symptoms - nausea, diarrhea, cutaneous/pulmonary sx
  • Hyperinfection – fever, pulm, sepsis
  • Symptoms related to invasion (itchy rash)

18

what bug is this?

Strongyloides stercoralis

19

How is Strongyloides stercoralis diagnosed?

  • LARVA (non-infectious; feces), serology
  • Hyperinfection

    • blood culture - gram (-) rods
       
    • sputum exam with microscopic ring worm larvae

20

How is Strongyloides stercoralis treated?

  • Bendazole (or Ivermectin)
  • Wear shoes! 

21

What worm is this?

Ascaris lumbricoides    

22

Life-cycle of this bug?

  • EGG ingestion > develops into larvae that penetrates the bowel wall > migrates to the lungs and break into alveoli space > coughed up and swallowed
     
  • Mating occur in the small bowel g produces egg that are shed in feces (can contaminate agriculture) 
     

23

Where does ascaris usually affect?

  • SE USA
  • Northeast pigs
  • Tropics (haiti)

24

What are the symptoms of Ascaris?

  • Light infection = Asxs; excreted into stool (usually freaks people out)
     
  • Heavy infection > gut/bile obstruction, malabsorption
  • Hemorrhagic pneumonitis (eosinophilic pneumonia) in lung

25

What is this? How is it diagnosed

ascaris lumbricoides

EGG (feces) – see lumpy bumpy coat

26

How do you treat Ascaris lumbricoides?

Piperazine – paralyzes the worm 

27

What are the two types of Larva Migrans?

what is it also known as?

  • Visceral Larva Migrans
  • Ocular Larva Migrans
  • aka Dog/cat Ascarid “Toxocariasis”

28

Life cycle of Visceral Larva migrans?

  • EGG ingested from dog/cat feces in soil
     
  • Eggs hatch > larvae penetrates the intestinal wall, travel with the blood stream to various organs ((liver, heart, lungs, brain, muscle, eyes) and cause local reactions

29

What are the dead end hosts for visceral larva? Why?

humans are dead-end, accidental hosts (it can infect but not mature/complete its life cycle in humans; ie no eggs in stool; usually completes its life cycle in dogs)

30

Who does visceral larva migrans affect?

Mostly kids

31

Clinical presentation of visceral larva migrans?

  • Asxs that progresses to fever, hepatomegaly
     
  • Retinoblastoma-like in eye (blood work shows eosinophilia compared to Rb)

     

32

How do you diagnose visceral larva migrans?

  • Serology
  • Tissue Bx - eosinophilic granuloma

33

What is this?

Visceral Larva Migrans

34

Treatment for Visceral Larva Migrans?

  • Bendazole
  • Diethylcarbamazine

35

two types of flatworms? 

  • Flukes – reproduce sexually in humans, asexually in snails
  • Tapeworms – scolex/head, mucosal attachment by sucker/hooklets, proglttids produce eggs, distal most mature, absorb nutrients in intestine through entire length of body

36

What is this?

Schistosomiasis (Flukes)

S. mansoni (lateral spike)

37

What is this?

Schistosomiasis (Flukes)

S. hematobium (apical)

38

What is this?

Schistosomiasis (Flukes)

S. japonicum (smallest)

Jen remembers this one because it looks like the Japanese flag.

39

What is the general life cycle of Schistosomiasis (Flukes)?

  • CERCARIA (released from snails) penetrates unbroken skin and enters circulatory system to reach the portal vein, where it mature into adults.
  • Paired adult worms migrate to mesenteric/bladder veins and mature to adult form -> produce EGGS that
    • burrow through the intestinal wall and shed in stool/urine, back to water to snails
    • cause disease by circulating back to the liver




       

40

Why is it that there is no host immune reaction against  Schistosomiasis (Flukes)?


Adults adopt host antigens, rapidly turnover their surface coat = NO host immune reaction!
 

41

Where does schistosomes usually occur?

Freshwater

Tropics

Egypt

42

symptoms of schistosomiasis??

 

  • Early Sx: fever, eosinophilia
    Liver – “pipestem fibrosis” = cirrhosis, portal HTN, ascites and esophageal varices
    • biosynthetic function is maintained eg. clotting factors and albumin levels are not markedly changed
  • Egg granulomas in lung, brain, spinal cord

  • Bladder: hematuria or SCC (due to chronic inflammation)

  • Swimmer’s Itch – cercariae in skin
     

43

What worm causes Pipestem fibrosis?

What is the immune response like?

Schistosomiasis (Flukes) -  acute TH1 response with IFNG and TNF, but as chronic disease supervenes, shift toward TH2 with eosinophilia, fibrosis

44

How do you diagnose Schistosomiasis (Flukes)?

  1. EGG (O&P of stool, biopsy)
  2. Rectal Biopsy – detect old infections

45

How is Schistosomiasis (Flukes) treated?

Praziquantel  (does not work as prophylaxis)