PID 1

Question 1

definition parasitism

Answer 1

non-mutual symbiosis where one species (parasite) lives at the expense of the other (host) causing damage

Question 2

mechanical damage example

Answer 2

Ascaris suum in pigs –> occlusion of the intestines

Question 3

traumatic damage example

Answer 3

hookworms attach in epithelium with buccal capsule

Question 4

inoculation of pathogens example

Answer 4

ticks

Question 5

malabsorption example

Answer 5

protozoan Gardia –> increase intestinal permeability

Question 6

definitive host definition

Answer 6

where sexual stages of parasites develop

Question 7

practical definition of definitive hosts

Answer 7

vertebrate

Question 8

intermediate host

Answer 8

where parasite evolves into a further stage of development

Question 9

terminal host

Answer 9

intermediate host that doesn’t allow transmission

Question 10

paratenic host

Answer 10

where parasite is simply carried

Question 11

biological versus mechanical vectors

Answer 11

biological plays a role in lifecyle whereas mechanical only carries parasite passively

Question 12

direct lifecycle

Answer 12

when it is completed in a single host

Question 13

definition of helminths

Answer 13

worms

Question 14

categories of helminths

Answer 14

plathelminths (flatworms= trematoda + cestoda) and nematoda (=roundworms)

Question 15

trematoda definition

Answer 15

bi-laterally symmetrical, leaf-like, no body cavity

Question 16

cestoda

Answer 16

elongated, segmented as adults, no body cavity

Question 17

nematoda

Answer 17

circular in cross-section, body cavity

Question 18

basic morphology of nematodes

Answer 18

body covered with cuticle, body cavity ‘tube within a tube’ is pseudocoelom, mouth sometimes opens into a buccal capsule

Question 19

forms of oesophagus of nematodes

Answer 19

filariform = bursate nematodes / bulb-shaped = ascaridoids/ double-bulb shaped = oxyuroids / muscular-glandular /trichuroid= capilary form of signle column of cells/ rhabditiform ) anterior and posterior swelling

Question 20

nematodes: difference of intestine between females and males

Answer 20

females= terminates in an anus, in males terminates into a cloaca where vas deferens opens

Question 21

definition spicules

Answer 21

accessory male organs, inserted in the female genital opening during copulation, guide the sperm, important for identification

Question 22

copulatory bursa

Answer 22

embraces female during copulation, supported by bursal rays

Question 23

basic life cycle of nematodes

Answer 23

larval stages L1/L2/L3 are infectlive stages, L4 and L5 which is the immature adult

Question 24

direct life cycle in nematodes

Answer 24

female lays eggs –> excreted –> L1 –> L2/L3 –> new host eats L3 (except in hookworms that penetrate skin or ascarids that develop into larvae after being ingested)

Question 25

indirect lifecyles of nematodes

Answer 25

L1/L2 in intermediate host –> infection of final host by ingestion of intermediate host or inoculation of L3s

Question 26

what is the pre-patent period (PPP)

Answer 26

the time elapsed between infection and detectable evidence of the parasite (eg: detection of eggs/cysts in the faeces)

Question 27

optimum temperature for development of maximum number of larvae of nematodes

Answer 27

18-26°C

Question 28

optimal humidity for larval development

Answer 28

100%, but microclimate in the faeces or in soil may provide sufficient humidity

Question 29

hypobiosis

Answer 29

seasonal arrested development

Question 30

preparturient rise (PPR) in faecal egg counts

Answer 30

increase in nematode eggs in the faeces around parturition, more marked in ewes, sows and goats

Question 31

trematoda (flukes) morphology

Answer 31

muscular suckers, tegument covered with spines, no body cavity,

Question 32

trematoda sexual organs

Answer 32

hermaphrodites –> cross or self-fertilisation

Question 33

basic life cycle of trematoda

Answer 33

see picture

Question 34

cestoda (tapeworms) basic morphology

Answer 34

head/scolex with 4 suckers with hooks –> short unsegmented neck –> chain of segments = strobila each segment being a proglottid

Question 35

sexuality of proglottids

Answer 35

hermaphrodites