Parasites

Question 1

What is a parasite?

Answer 1

Organisms which inhabits another organism (host) and benefits by deriving nutrients at the others expense

Question 2

What is symbiosis?

Answer 2

Organisms lives in close association

Question 3

What is mutualism?

Answer 3

both species benefit from the interaction

Question 4

What is Parasitism?

Answer 4

parasite derives benefit and the host gets nothing in return but always suffers some injury

Question 5

What is commensalism

Answer 5

parasite only is deriving benefit without causing injury to the host

Question 6

What is definitive host?

Answer 6

Host harbours adult/or sexual reproduction occurs (humans usually definitive)

Question 7

What is the Intermediate host

Answer 7

Host harbours lavae/asexual stages of parasite

Question 8

What is the paratenic

Answer 8

Parasite is viable with no further development

Question 9

How are parasites classified?

Answer 9

Protozoa - micro parasites Helminths - macro parasites (worms)

Question 10

How are helminths subdivided?

Answer 10

Platyhelminths - flat worms Nematodes - round worms

Question 11

What is involved in a direct life cycle?

Answer 11

Only one host - definitive host

Question 12

What is meant by a simple indirect life cycle?

Answer 12

2 hosts - definitive (adult and sexual stage) and intermediate stage (asexual/lavae stage)

Question 13

What is meant by a complex life cycle?

Answer 13

More than 2 intermediate hosts and definitive host; there can be paratenic host too

Question 14

Describe the ascariasis lifescycle..

Answer 14

Direct lifecycle - human = definitive host

Question 15

Describe the 2 phasis of ascariasis..

Answer 15

Lung migration phase - loefflers syndrome - dry cough, dyspnea, wheese

Intestinl phase - worm burden - malnutrition

Question 16

How is ascariasis diagnosed?

Answer 16

Eggs/worms in faeces

Question 17

How is ascariasis treated?

Answer 17

Albendazole

Question 18

What is the life cycle of schistomiasis?

Answer 18

Male/female reporduce in human (definitative host) -> eggs releases in faeces -> infect snails (intermediate host) ->asexual reproduction in snail forming motile larvae -> penetrate human skin and blood vessels

Question 19

What are the clinical manifestations of schistomiasis?

Answer 19

• Swimmers itch
• Katayama fever
• Chronic schistomiasis
• Urinary schistomiasis - haematuria, bladder fibrosis, squamous cell carcinoma in bladder
• hepatoschitomiasis - portal hypertension, liver cirrhosis, abdo pain, hepatosplenomegaly

Question 20

How is schistomiasis treated?

Answer 20

Praziquatel

Question 21

What type of host are humans in hydatid diease?

Answer 21

Intermediate Host - accidental host (usually dogs/sheep)

Question 22

What is the life cycle of a hydatid disease?

Answer 22

Humans are the intermediate host - catch it from faeces of dogs (as dogs dont eat humans, usually stops at humans) - naturally, passes to sheep and dogs eat sheep

Question 23

What are the clinical manifesatations of hydatid disease?

Answer 23

Cysts - 70% liver, 20% lungs

Question 24

What type of parasite is malaria?

Answer 24

Protozoa (micro) - plasmodium

Question 25

WHat is the host of malaria?

Answer 25

Female anopheles mosquito

Question 26

What plasmodium type is most clinically relevant?

Answer 26

P Falciparum

Question 27

What are the clinical features of malaria?

Answer 27

Rupture RBCs, block capillaries and cause inflammatory reactions (associated symptoms)

Question 28

What is the lifecycle of cryptosporis?

Answer 28

DIrect life cycle - humn are the only host (feacal oral contamination)

Question 29

CLinical features of cryptosporis

Answer 29

Incubation period (2-10 days)

Watery, mucous diarrhoea (no blood)

Self limiting - up to 2 weeks

Bloating, nausea, cramping, vomiting

Question 30

How does cryptosporis spread?

Answer 30

Human -> human - swimming pools, child care workers, resisdents/carer, healthcare workers, traveller

Animal -> human - backpackers, farm workers, visits to farms/petting zoos