Eukaryotic Parasites 1

Question 1

What is a parasite?

Answer 1

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

Question 2

What are ectoparasites?

Answer 2

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

Question 3

What is the definitive host?

Answer 3

the host in which the parasite reaches sexual maturity

Question 4

What is the intermediate host?

Answer 4

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

Question 5

What is the paratenic host?

Answer 5

a host where the parasite does not undergo development

Question 6

What is the reservoir host?

Answer 6

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

Question 7

What are three species of lice?

Answer 7

pediculus humanis, p. capitis, phthirus pubis

Question 8

What type of parasite are lice?

Answer 8

obligate blood sucking insect

Question 9

What is an infection by live called?

Answer 9

pediculosis

Question 10

What is the pediculus humanis?

Answer 10

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

Question 11

What is the p. capitis?

Answer 11

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

Question 12

What is p. pubis?

Answer 12

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

Question 13

What is the life cycle of p. capitis?

Answer 13

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

Question 14

What is irritant about lice?

Answer 14

Both the lice themselves and their malt

Question 15

What is the distribution of lice?

Answer 15

worldwide

Question 16

What is the treatment of lice?

Answer 16

topical insecticides

Question 17

What is sarcoptes scabei?

Answer 17

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

Question 18

Where do scabies typically infect?

Answer 18

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

Question 19

How are scabies spread?

Answer 19

Contact

Question 20

What is the life cycle of scabies?

Answer 20

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

Question 21

What is the distribution of scabies?

Answer 21

worldwide

Question 22

What is the treatment for scabies?

Answer 22

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

Question 23

Why are ticks important in disease?

Answer 23

Because they are a vector for many infectious diseases

Question 24

What direct disease can ticks cause?

Answer 24

paralysis - either localised or generalised ascending

Question 25

Are humans the natural host for ticks?

Answer 25

no

Question 26

How is paralysis from ticks treated?

Answer 26

Removal of tick

Question 27

What are protozoa?

Answer 27

Single cells organisms that are mainly non parasitic

Question 28

Why are protozoa not truly parasitic?

Answer 28

because they can live outside the host

Question 29

What are the two forms the protozoa exist as?

Answer 29

trophozoites and cysts

Question 30

What is entamoeba histolytica?

Answer 30

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

Question 31

How is entamoeba transferred?

Answer 31

fecal-oral transmission - ingested as cysts

Question 32

What is the distribution of entameoba histolytica?

Answer 32

worldwide - but unlikely in places with sewage treatment

Question 33

What are the symptoms of infection by entameoba histolytica?

Answer 33

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

Question 34

What is the treatment for entameoba histolytica?

Answer 34

metronidozole and paromomycin and drainage of abscess

Question 35

Do humans develop immunity to entameoba histolytica?

Answer 35

very little

Question 36

What is giardia intestinalis?

Answer 36

a flagellate protozoa parasite that causes diarrhoea and malabsorption

Question 37

How is giardia intestinalis spread?

Answer 37

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

Question 38

What is the distribution of giardia intestinalis?

Answer 38

worldwide

Question 39

What is the treatment of giardia intestinalis?

Answer 39

tinidazole

Question 40

How is giardia intestinalis diagnosed?

Answer 40

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

Question 41

Do humans develop an immunity to giardia intestinalis?

Answer 41

No

Question 42

What is toxoplasma gondii?

Answer 42

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

Question 43

What is the clinical presentation of toxoplasma gondii?

Answer 43

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

Question 44

Who is at risk with a toxoplasma gondii infection?

Answer 44

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

Question 45

How do you get an infection with toxoplasma gondii?

Answer 45

usually from undercooked meat

Question 46

How long does an infection of toxoplasma gondii last?

Answer 46

it is lifelong

Question 47

In what animals do toxoplasma gondii sexually reproduce?

Answer 47

cats

Question 48

Why should pregnant women avoid infection?

Answer 48

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

Question 49

What is the distribution of toxoplasma gondii?

Answer 49

worldwide

Question 50

What is the treatment of toxoplasma gondii?

Answer 50

In an immunocompromised patient use bactrim