Intro to Parasitology

Question 1

Parasite definition

Answer 1

“Dependence for food and shelter”

Question 2

Endoparasite

Answer 2

On the inside (gut, heart, lungs, blood, repro tract)

Question 3

Types of Endoparasites

Answer 3

• Protozoa; coccidia, malaria, tick fevers

- Worms; nematodes, cestodes, trematodes

Question 4

Nematodes

Answer 4

Round worms

Question 5

Cestodes

Answer 5

Tape worms

Question 6

Trematodes

Answer 6

Flukes

Question 7

Ectoparasites

Answer 7

On the outside (skin & adnexa)

• Insects; flies, midges, mosquitoes, fleas, lice
• arthropods; ticks and mice

Question 8

Definitive host

Answer 8

Host in which parasite become sexually mature

Question 9

Intermediate host

Answer 9

(obligatory) temporary environment for parasite

- does not reach sexual maturity here but can undergo asexual reproduction/obligatory development

Question 10

Paratenic (transfer) host

Answer 10

Parasite does not undergo development, but remains alive and infective to another host

Question 11

Vectors

Answer 11

Any organism (esp arthropods) that serve as IH as well as carriers for protozoans or other small parasites

Question 12

Reservoir host

Answer 12

Animals that harbour an infection that can be transmitted to humans

Question 13

3 Parasite factors

Answer 13

1. Dose
2. Virulence
3. Infectivity

Question 14

5 Host factors

Answer 14

1. Innate resistance
2. Previous exposure
3. passive immune status (neonates)
4. Reproductive status (preg/lact. vs non-preg, sterile vs intact)

Question 15

5 Environmental factors

Answer 15

1. Animal stocking density
2. animal movement between groups (rotational vs cont. grazing), quarantine of new stock
3. Housing (e.g. ventilation, sanitation)
4. Environmental conditions (e.g. temp, rainfall)
5. Nutrition (energy balances)

Question 16

HxP interaction ultimate goal

Answer 16

Both host and parasite to survive and reproduce

Question 17

How clinical signs are caused

Answer 17

• removal of e.g. blood, metabolites
• loss of body fluids
• interference w absorption (ingested foods)
• blockage of e.g. heart
• irritation; larvae in airway
• migration; into CNS

=> ‘ill thrift’, diarrhoea, anaemia

Question 18

Production of pathology

Answer 18

• production of toxin/excreted foreign materia
• migration through tissues/ residence in tissues
• host reaction; allergies and inflammation

Question 19

Host specific

Answer 19

Narrow host range, well adapted, niche relation

1. Often seen IH»DH relations

Question 20

Non host-specific

Answer 20

1. Broad host range
2. Possibility of paratenic host
3. Possibility of zoonosis

Question 21

Direct parasite life cycle

Answer 21

1. Free-living stages outside host
2. Infective stage in environment
3. Parasitic stages in final (definitive) host

Question 22

Indirect life cycle

Answer 22

Consists of definitive (final) and IH

• IH (rabbit), vector-parasite (fleas), unrelated hosts (snails for flukes)
• when IH involved, LC is INDIRECT