Lecture 3A - Parasites and Viruses

Question 1

What forms can parasites adopt?

Answer 1

ectoparasits e.g. fleas, head lice

endoparasites - worms

singe cell - protozoa e.g. plasmodium species

viruses

Question 2

What are endoparasites?

Answer 2

large multicellular parasites like worms

can invade and multiply inside the body and take up residence in tissue spaces

Question 3

What are protozoa?

Answer 3

single celled organisms, which can spend part of their life cycle reproducing inside cells

Question 4

What do viruses and prions need to reproduce?

Answer 4

the assistance of the intracellular metabolic machinery of the host organism

Question 5

Cysticercosis?

Answer 5

1000 hospitilsations/year
Taenia solium tapeworm

makes it’s home in human tissue such as brain and muscles

Question 6

Where are larval cysts of taenia solium found?

Answer 6

in uncooked pork

Question 7

Chagas disease?

Answer 7

300,00 infections

leads to long term digestive, cardiac and neurological complications if not treated

Question 8

What causes chagas disease?

Answer 8

trypanosoma cruzi (T.cruzi)

Question 9

Trichomoniasis?

Answer 9

STD (3.7 million infected)

only 30% have symptoms of itching and burning with urination

Question 10

What causes trichomoniasis?

Answer 10

protozoan - trichomonas vaginalis

Question 11

Toxocara?

Answer 11

caused by larvae of roundworm found in guts of dogs and cats

can cause eye disease/blindness especially in children

Question 12

What causes toxocara?

Answer 12

Toxocara canis or T. cati

50 million have antibodies

Question 13

Toxoplasma gondii?

Answer 13

protozoan

from cat faeces

causes swollen lymph nodes, muscle aches and eye complications - can become chronic if not treated

Question 14

What are ectoparasites?

Answer 14

live on the surface of a host but need some product from(nutrient or genetic material) in order to survive (often a blood meal)

Question 15

What can ectoparasites do when taking a blood meal?

Answer 15

inject viruses, protozoans and bacteria along with some form of anti-coagulant into the human subject

Question 16

Where do endoparasites live?

Answer 16

inside the body

Question 17

Examples of ectoparasites?

Answer 17

head lice

ticks (vectors for chagas disease, lyme disease)

mites

fleas

Question 18

Headlice?

Answer 18

pediculus humanus capitis

wingless insects very common in school children aged 4-11

Question 19

How is head lice transferred?

Answer 19

by head to head contact

Question 20

How do head lice attach to the host?

Answer 20

the female cements pinhead sized eggs to hairs near to the root where the scalp keeps them warm

Question 21

How long does it take head lice to hatch?

Answer 21

around 9 days (white nit stage), but they initially remain attached to the hair, later they begin feeding

Question 22

How do head lice feed?

Answer 22

by biting the scalp and drawing blood

in another 9-10 days they are fully mature and the females are able to lay more eggs

Question 23

How can head lice be treated?

Answer 23

by combing (0.2-0.2mm comb) or lotions

Question 24

Body lice?

Answer 24

pediculosis corpis

Question 25

Pubic lice?

Answer 25

phthirus pubis

Question 26

Where do body/pubic lice live?

Answer 26

they live and feed on specific skin regions

Question 27

What are mites?

Answer 27

arachnids

Question 28

Sarcoptes scabei?

Answer 28

mite that causes scabies - female burrows into the skin and lays eggs

Question 29

Dermatophagoides pteronyssinus?

Answer 29

dust mite

lives off dead skin and causes dermatitis and asthma

Question 30

Ticks?

Answer 30

also arachnids

live on the skin and feed off blood

Question 31

What do ticks act as?

Answer 31

vectors for many serious illnesses in humans and animals

Question 32

Fleas?

Answer 32

wingless insects with an extraordinary ability to jump

eggs may hatch in carpets for more than a week before the flea hatches and jumps onto the skin of the host for a blood meal

Question 33

What can lice transmit?

Answer 33

typhus

can be transmitted in clothing or reside there between baths

Question 34

What can ticks transmit?

Answer 34

chagas disease and lyme disease

Question 35

Size of fleas?

Answer 35

1.5 to 3mm long, but can jump vertically 18cm and horizontally 33cm