Intro to parasites

Question 1

What are the 2 types of parasites that infect humans (other than a few inscts)

Answer 1

1. Helminths

2. protozoans - single cell

Question 2

Define definitive host and dead-end host

Answer 2

definitive: contains sexually mature, adult parasite

dead-end: blocks transmissiono

Question 3

What is a common feature of helminth infections

Answer 3

they suppress the immune system

Question 4

Where do they multiply with respect to humans:
protozoans
helminths

Answer 4

protozoans: within human
Helminth: outside (lay eggs aoutside and must be re-ingested)

Question 5

6 parasites prevalent in US (plus one extra in kentucky few decades ago)

Answer 5

1. Pinworms (enterobius vermicularis)
2. toxoplasma gondii
3. Trichomonas
4. Pediculus humanus capitus (head lice) -only head-head contact
5. Giardia:
6. Ameoba: E. histolytica, N. fowleri
   - -Nematodes (ascaris, stronglyoides

Question 6

8 MC worldwide in order from MC -LC

Answer 6

1. Big 3 nematodes: roundworm > hookworm > whipworm
2. Filarial worms (W. bancrofti–> elephantitis)
3. Malaria
4. Schistosomes (flukes)
5. E. Histolytica
6. Trypanosomes
7. Leshmaniasis

Question 7

Intra- vs. Extracellular protozoan pathogenesis (very general)

Answer 7

extra: compete for nutrients
intra: cell and tissue destruction

Question 8

What is one of the on;y parasite to releas a toxin

Answer 8

E. histolytica

Question 9

Serological testing is avaialable for what 3 US prevalent parasites

Answer 9

toxoplasma, Trichomonas, Giardia

Question 10

How is plasmodium falciparum dx?

Answer 10

PCR

Question 11

Why is dosing an issue with anti-parasitic druigs

Answer 11

bc they target eukaryotic cells

Question 12

What drug is MC for protozoans, and which is MC for worms/flukes? and MOA

Answer 12

Protoz: metronidazole: converted to active agent only in anaerobes–> DNA damage

worms: Benzamidazoles: interfere with tubulin function

Question 13

Which proto is resistant to chlorination

Answer 13

Giardia

Question 14

What disease does E. histolytica cz and pathogenesis

Answer 14

Amoebiasis: dysentery

Question 15

Naegleria fowleri: disease, habitiat, human host designation

Answer 15

warm fresh water
invades nasal mucosa to cause meningitis
humans are a dead-end host

Question 16

E. histolytica: habitat, life forms (2), virulence factor and it’s moa

Answer 16

habitiat: human waste
forms: trophozoite and cyst
produces a cytotoxin–> lyse cells –> tissue invasion (thus histoLYTICa)

Question 17

transmission of E.histolytica, and what hosts is it found in?

Answer 17

fecal-oral (gay dudes)

only host is HUMANS!!

Question 18

Histo of E. histolytica infx

Answer 18

****Flask-shaped ulcer

Question 19

What can a chronic E.histolytica infx cause?

Answer 19

IBD

Question 20

Other than the intestine, where else can E. histolytica infect? Presentation in this location?

Answer 20

liver - cuases “anchovy-paste abscesses”

Question 21

CP of E. histolytica infx

Answer 21

gradual onset of bloody diarrhea, abd pain, maybe fever

Question 22

How is E. histolytica infx diagnosed (1 for class, 2 for sketchy)

Answer 22

class: ELISA for antigens in stool
sketchy:
“trophozoite w/ endocytosed RBCs”
Intestinal bx: flask-shaped lesions

Question 23

Dx of N.fowleri

Answer 23

exam of CSF

Question 24

E. histolytica tx? (2)

Answer 24

metronidazole

iodoquinol

Question 25

Iodoquinol MOA

Answer 25

iron chelator

Question 26

warning signs about swimming in water are warning against what protozoa

Answer 26

n. fowleri