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Flashcards in Eukaryotic Parasites 1 Deck (50):
1

What is a parasite?

a plant or animal that lives on or in another living organism on which it is metabolically dependent

2

What are ectoparasites?

parasites which get metabolic benefit from interaction with cutaneous surface - most are insects such as lice or arachnids such as mites and ticks

3

What is the definitive host?

the host in which the parasite reaches sexual maturity

4

What is the intermediate host?

a host in which development occurs but the parasite does not reach sexual maturity

5

What is the paratenic host?

a host where the parasite does not undergo development

6

What is the reservoir host?

an animal that is infected with a parasite that also infects people

7

What are three species of lice?

pediculus humanis, p. capitis, phthirus pubis

8

What type of parasite are lice?

obligate blood sucking insect

9

What is an infection by live called?

pediculosis

10

What is the pediculus humanis?

A body louse that lives on body hair but lays eggs on clothing

11

What is the p. capitis?

A head louse - lays eggs at the base of hair stalks

12

What is p. pubis?

a pubic louse - can only attach and lady eggs on oval shaped hairs so can’t infect the head

13

What is the life cycle of p. capitis?

louse emerges from the egg, goes through malting, becomes sexually mature and reproduces and then lays eggs on the hair shaft - whole life cycle on the hair

14

What is irritant about lice?

Both the lice themselves and their malt

15

What is the distribution of lice?

worldwide

16

What is the treatment of lice?

topical insecticides

17

What is sarcoptes scabei?

A type of mite - causes scabies - an arachnid not an insect

18

Where do scabies typically infect?

They form tunnels in the epidermis of finger webs, elbows, axillae, genitals

19

How are scabies spread?

Contact

20

What is the life cycle of scabies?

adult females deposit eggs as they burrow, eggs hatch and release larvae, larvae malt and mature into adults to lay eggs again - eggs are transferred by scratching area around the burrow

21

What is the distribution of scabies?

worldwide

22

What is the treatment for scabies?

ivermectin or topical scabicides - and hot water wash clothing and bedding to avoid reinfection

23

Why are ticks important in disease?

Because they are a vector for many infectious diseases

24

What direct disease can ticks cause?

paralysis - either localised or generalised ascending

25

Are humans the natural host for ticks?

no

26

How is paralysis from ticks treated?

Removal of tick

27

What are protozoa?

Single cells organisms that are mainly non parasitic

28

Why are protozoa not truly parasitic?

because they can live outside the host

29

What are the two forms the protozoa exist as?

trophozoites and cysts

30

What is entamoeba histolytica?

an amoeba which invades the colon but can spread through the blood to the brain or liver and cause abscess

31

How is entamoeba transferred?

fecal-oral transmission - ingested as cysts

32

What is the distribution of entameoba histolytica?

worldwide - but unlikely in places with sewage treatment

33

What are the symptoms of infection by entameoba histolytica?

prolonged watery diarrhoea or may present as more acute bloody diarrhoea - or mate present with symptoms of abscess

34

What is the treatment for entameoba histolytica?

metronidozole and paromomycin and drainage of abscess

35

Do humans develop immunity to entameoba histolytica?

very little

36

What is giardia intestinalis?

a flagellate protozoa parasite that causes diarrhoea and malabsorption

37

How is giardia intestinalis spread?

Either via fecal-oral transmission or zoonotic transmission (e.g. possums contaminating rainwater tanks)

38

What is the distribution of giardia intestinalis?

worldwide

39

What is the treatment of giardia intestinalis?

tinidazole

40

How is giardia intestinalis diagnosed?

microscopy of faeces to look or cysts or serological test of feaces

41

Do humans develop an immunity to giardia intestinalis?

No

42

What is toxoplasma gondii?

an obligate intracellular parasite that can infect all mammals and many birds

43

What is the clinical presentation of toxoplasma gondii?

In people with a normal immune system there is insignificant presentation - mild cervical lymphadenopathy and mild fever that is self resolving

44

Who is at risk with a toxoplasma gondii infection?

immunocompromised patients - can cause CNS lesions or ocular disease and can be fatal

45

How do you get an infection with toxoplasma gondii?

usually from undercooked meat

46

How long does an infection of toxoplasma gondii last?

it is lifelong

47

In what animals do toxoplasma gondii sexually reproduce?

cats

48

Why should pregnant women avoid infection?

Because an acute infection during pregnancy can lead to miscarriage or foetal abnormalities

49

What is the distribution of toxoplasma gondii?

worldwide

50

What is the treatment of toxoplasma gondii?

In an immunocompromised patient use bactrim