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Flashcards in Immunology - week 3 parasites 2 Deck (55)
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1

What organism causes Entameoba histolytica?

Amebiasis

2

How is Amebiasis transmitted?

Ingestive - direct fecal/oral - anal sex

3

How can you tell the difference between trophozoites in an invasive disease of Amebiasis and cysts in a non-invasive case of Amebiasis?

Trophozoites: Diarrheal stool Cysts: formed stool

4

What is the life cycle of Entameoba histolytica?

1) Infective acid-resistant cysts ingested, excystation in colon 2) Trophozoites attach to colonic mucin and divide 3) Resistant cysts form in colon and shed in feces 4) Trophozoites can penetrate the mucosal layer which leads to invasive disease

5

What is the pathology of Amebiasis? (3)

1) Carriers: Chronic for months or years - shed millions of cysts per day

2) Dysentary: Severe bloody diarrhae - invade colonic epithelium and submucosal ulcers

3) Invasive: Rare - dissemination throughout body but mostly liver (not always associated with diarrhea)

6

How do you diagnosis Amebiasis? (2)

1) cysts in stool or trophozoites in bloody diarrhea 2) travel history is essential (amebiasis often picked up in developing countries)

7

How is Giardia transmitted?

Ingesitive: fecal/oral from animals also from anal sex ex. animal poops in stream and you drink water and get it

8

What is the lifecycle of Giardia?

1) injest cysts - trophozoites excyst in upper small intestine 2) encystation in colon 3) excrete cysts in stool (trophozoites are very unstable outside body)

9

What's the pathology of Giardia?

Onset of 2 weeks, asympotomatic to "explosive" diarrhea Most people don't need treatment

10

What are the apicomplexan parasites of humans? (4)

cryptosporidium

Toxoplasma

plasmodium

Babesia

11

What are common characteristics with Apicomplexan Parasites?

Obligate intracellular parasites (must invade to live)

12

How are Cryptosporidiosis transmitted?

Fecal oral transmission

13

Where does Cryptosoporidiosis reside in the body?

Intestine

14

What is unique regarding the lifecycle of Cryptosporidium? Why is this important?

Extra-cytoplasmic - developmental cycle in brush boarder Important: difficult to treat - aids/immune compromised patients particularly vulnerable

15

What is the pathology of Cryptosporidiosis? (3)

1) 3 or more loose watery bowl movements per 24 hours 2) Symptoms similar to giardia but more diahhrae and fluid loss 3) Healthy people have an immune response to clear parasite

16

How is Cryptosporidiosis diagnosed?

2-5 mm cysts in stool - red cup and saucer shaped

17

What is the definitive host for Toxoplasmosis?

Cats

18

How is Toxoplasmosis transmitted?

Ingestive: fecal/oral and undercooked meat (can be in any warm blooded animal) Transplacental: congenital infection (which is why it's so important for pregnant woman)

19

What is the lifecycle of toxoplasmas?

1) Oocytes shed by cats - can last for a while in environment 2) ingested by warm blooded animal where it goes through sexual reproduction 3) Goes into muscle or neuronal tissue: cysts form 4) animal gets eaten

20

When should a pregnant woman not be worried about Taxoplasmosis?

If a pregnant woman has already been exposed to it then they will have developed an immune response and will be immune to a secondary infection

21

Why is Toxoplasma dangerious for pregnant women?

Toxoplasma easily crosses the placenta and grows well in the brain tissue of the fetus causing lots of problems (usually abortion)

22

How is Toxoplasmosis diagnosed?

1) serology - use an indirect immunofluoresence (IFA) 2) confusion or seizure

23

What is a ring enhancing lesion?

areas of edema where cysts in brain have started to grow again

24

How can you tell if a ring enhancing lesion is caused by cancer or taxoplasma?

If taxoplasma there will be more than 1

25

What does it mean if your serology revealed the following: Positive for Toxo-specific IgG? Positive for Toxo specific IgM? High IgG avidity? Low IgG avidity? Positive for IgG but not IgM?

Positive for Toxo-specific IgG: infected at some point with Toxoplasmosis Positive for Toxo specific IgM: infected within past 2 years High IgG avidity: infected 12 weeks or more prior Low IgG avidity: possibly a recent infection Positive for IgG but not IgM: chronic infection - infected for greater than six months

26

Why is gardening a risk for taxoplasmosis?

Because the oocyte can survive in soil and they're hard to wash off

27

What does Babesiosis infect?

red blood cells

28

What is the definitive host of Babesiosis?

Deer tick

29

Who is the intermediate host for Babesia?

mice and small mammals

30

Who is the accidental host for Babesia?

humans