4/10 Parasitology and Travel Med I

Question 1

2 kinds of worms

Answer 1

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

Question 2

indication of worm infection?

Answer 2

eosinophilia

Question 3

T/F worms multiply in hosts

Answer 3

mostly false. most do not multiply in hosts

Question 4

in worm infections, what is disease state determined by?

Answer 4

disease is determined by infecting numbers

Question 5

general life-cycle of roundworm

Answer 5

• 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)

Question 6

standard trmt of roundworms?

Answer 6

Bendazole – inhibits microtubule function, immobilizes and kills worms

Question 7

What is this?

Answer 7

Pinworm

Enterobius vermicularis

Question 8

What is this?

Answer 8

Pinworm

Enterobius vermicularis

Question 9

What is the life cycle of the pinworm?

Answer 9

• 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

Question 10

Where do pinworms occur?

Answer 10

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

Question 11

How are Enterobius vermicularis diagnosed?

Answer 11

EGG, clear scotch tape prep from perianal area

Question 12

Enterobius vermicularis treatment?

Answer 12

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

Question 13

Strongyloides stercoralis general life cycle?

Answer 13

• 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

Question 14

How long can Strongyloides stercoralis last in the body?

When is it usually reactivated?

Answer 14

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

Question 15

What is hyperfinection? What is it caused by?

Answer 15

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

Question 16

Where is Strongyloides stercoralis found?

Answer 16

Worldwide - warm, moist climates

Question 17

symptoms of Strongyloides stercoralis?

Answer 17

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

Question 18

what bug is this?

Answer 18

Strongyloides stercoralis

Question 19

How is Strongyloides stercoralis diagnosed?

Answer 19

• LARVA (non-infectious; feces), serology
• Hyperinfection
  
  • blood culture - gram (-) rods
  • sputum exam with microscopic ring worm larvae

Question 20

How is Strongyloides stercoralis treated?

Answer 20

• Bendazole (or Ivermectin)
• Wear shoes!

Question 21

What worm is this?

Answer 21

Ascaris lumbricoides

Question 22

Life-cycle of this bug?

Answer 22

• 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)

Question 23

Where does ascaris usually affect?

Answer 23

• SE USA
• Northeast pigs
• Tropics (haiti)

Question 24

What are the symptoms of Ascaris?

Answer 24

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

Question 25

What is this? How is it diagnosed

Answer 25

ascaris lumbricoides EGG (feces) – see lumpy bumpy coat

Question 26

How do you treat Ascaris lumbricoides?

Answer 26

Piperazine – paralyzes the worm

Question 27

What are the two types of Larva Migrans? what is it also known as?

Answer 27

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

Question 28

Life cycle of Visceral Larva migrans?

Answer 28

* 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

Question 29

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

Answer 29

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)

Question 30

Who does visceral larva migrans affect?

Answer 30

Mostly kids

Question 31

Clinical presentation of visceral larva migrans?

Answer 31

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

Question 32

How do you diagnose visceral larva migrans?

Answer 32

* Serology * Tissue Bx - eosinophilic granuloma

Question 33

What is this?

Answer 33

Visceral Larva Migrans

Question 34

Treatment for Visceral Larva Migrans?

Answer 34

* Bendazole * Diethylcarbamazine

Question 35

two types of flatworms?

Answer 35

* **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

Question 36

What is this?

Answer 36

Schistosomiasis (Flukes) S. mansoni (lateral spike)

Question 37

What is this?

Answer 37

Schistosomiasis (Flukes) S. hematobium (apical)

Question 38

What is this?

Answer 38

Schistosomiasis (Flukes) S. japonicum (smallest) Jen remembers this one because it looks like the Japanese flag.

Question 39

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

Answer 39

* 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

Question 40

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

Answer 40

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

Question 41

Where does schistosomes usually occur?

Answer 41

Freshwater Tropics Egypt

Question 42

symptoms of schistosomiasis??

Answer 42

* 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

Question 43

What worm causes Pipestem fibrosis? What is the immune response like?

Answer 43

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

Question 44

How do you diagnose Schistosomiasis (Flukes)?

Answer 44

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

Question 45

How is Schistosomiasis (Flukes) treated?

Answer 45

Praziquantel (does not work as prophylaxis)