parasites

Question 1

define parasite

Answer 1

organism that lives on or in host and derives nutrients from that host.

Question 2

3 types of parasites

Answer 2

protozoa
helminths
ectoparasites

Question 3

protozoa
- describe
3 types

Answer 3

microscopic, one-celled organism, free-living or parasitic.
intestinal, blood, tissue.
intestinal - transmitted fecal oral route
blood/tissue - transmissed arthropod vectors

Question 4

ex of intestinal protozoa

• comes from?
• symptoms?
• protection? tolerant to?
• transmission?

Answer 4

giardia lamblia
comes from contaminated water
symptoms =diarrhea, greasy stools tend to float. cramps, nausea, vom, diarrhea
- protective outer shell allows it to survive outside body for long time
tolerant to chlorine disinfection - need to filter them out
tranmisssion by water

Question 5

ex: of 2nd intestinal protozoa
- comes from?
symptoms?
who is most susceptible?
what is infectious form?
protection? tolerance?

Answer 5

cryptosporidium
- comes from swimming pool/lakes. contaminated water.
- water diarrhea, dehydration, nausea, vomiting, fever, weight loss
immunocompromised most susceptible to severe infection.
infectious form = oocyst. little claws from egg attach to GI.
protected by outer shell allows it to survive outside body for long time. very tolerant to chlorine disinfection - need to filter.

Question 6

blood protozoa eX:
symptoms
transmission?
where does transmission occur?
most infectious species?

what does it do in body?
paracetemia increases when?

Answer 6

plasmodium spp. aka malaria
fever, chills, flu-like, can be fatal.
arthropod transmission – mosquito.
transmission in equtorial band - around equator.
falciparum = acts faster, and more drug resistant.
invasion of RBC and liver.
paracetemia increases as it matures/

Question 7

ex: tissue protozoa AKA
where found?
transmission?
symptoms? 
2 subtypes?

Answer 7

leishmania AKA neglected tropical disease
tropics,subtropics, europe.
arthropod - bite of sand flies
destroy tissue, bone of outer limbs and face
cutaneous (skin sores)
viscerl (internal organs)

Question 8

ex 2: tissue protozoa
transmission? 
parasite - infectious agent?
life cycle
symptoms - adult vs fetus (vertical transmission)

Answer 8

toxoplasma gondii
tranmission: food bourne, congenital, zoonotic transmission.
cyst = parasite, explodes with many particulates in it.
life cycle: oocysts produced in definitive host (cats). passed in feces, ingested by other animals. humans injest animals that are infected. the oocysts convert to rapidly multiplying which can spread around body and to fetus (vertical transmission) . then converts to dead end host.
usually asymptomatic. fetus = fetal demise, hearing loss.

Question 9

helminths describe general characteristic.
symptoms?
3 classes

Answer 9

large, multicellular organisms generally visible to naked eye in adult stages.
free-living or parasitic.
in adult form, cannot multiply.
- flatworms, thorny-headed worms, round worms

Question 10

ex: flatworms

Answer 10

helminths
flukes, tapeworms.
ex: paragonimus = long fluke infects human after eating infected raw/undercooked crab/crayfish.
doesnt multiply in host. gets into gut, circulates to lung. reswallow, pass in stool. or adult sets up shop. harmful if take nutrients or in CNS.

Question 11

ex: thorny-headed worms

Answer 11

adult forms reside in GI. intermediate btw flat and round worms.

Question 12

ex: roundworms

Answer 12

nematodes.
ascaris lumbricoides - tape worm. eats al nutrients.
adults live in intestine.
larvae burrow through intestinal wall, enter circulation and organs. larvae coughed up and swallowed - grow into adult in intestine.
parasitic drugs target eukaryotic cells = highly toxic to humans

Question 13

ex: roundworms 2 - pin worm

Answer 13

enterobius
small, thin, white worm.
where standard of care is lower.
treatable w over the counter medication.

Question 14

ectoparasites

Answer 14

ticks, fleas, live, mites.
attach or burrow into skin & stay there for long time.
symptoms = immune system response.

Question 15

ectoparasite ex: 1
- infestation of?
- reaction/symptoms?
spread how?

Answer 15

scabies
infestation of skin by human itch mite.
microscopic mite burrow into upper layer of skin. lives and lays egg.
egg = immune system response = itching, pimple-like skin
common symptoms - topical, non-invasive.
spread by prolonged skin-to-skin contact. usually sexually
not zoonotic.
worldwide

Question 16

ectoparasite ex 2 - lice

3 types

Answer 16

lice
head - 2.1-3.3 mm. infest head and neck. attach egg to base of hair shaft. move by crawling
body - 2.3-3.6 mm. live and lay eggs on clothing and only move to skin to feed.
pubic - smallest in size. typically found attached to pubic/coarse hair transmitted sexually

Question 17

ectoparasite 3 - botfly

Answer 17

myiasis
infection w fly larva, usually tropical/subtropical
lump develops in tissue as larva grows. 
wont travel through body
wont spread person-person
treatment surgical.

Question 18

4 methods of control of parasites

Answer 18

1. clean water - some resistant to bleach
2. clean environment - wash hands
3. cooking foods - parasites destroyed by adequate cooking
4. treatment - most therapies toxic to host.