PID 3

Question 1

life cycle for all of these

Answer 1

direct life cycle –> male and female live somewhere –> infective stage L3 –> ingested again …

Question 2

morphological feature of Nematodirus

Answer 2

cephalic end –> bubble

Question 3

epidemiology: hypobiosis

Answer 3

arrested development, facultative, involves only part of the parasite population, mechanism of defense (parasite waits for

Question 4

arrested development in sheep

Answer 4

in ewes following grazing season –> don’t let parasite develop in the mucosa of the abomasum

Question 5

peri-parturient rise in feacal count in sheep

Answer 5

increase in feacal egg count in adults –> increase in egge output in the feces on the mothers –> something to do with the immunological status during pregnanacy –> progesterone –> parasites resume development during pregnancy

Question 6

function of progesterone

Answer 6

suppresses immunity

Question 7

important thing about PPR

Answer 7

main source of infection in lambs

Question 8

Teladorsagia circumcincta: morphology

Answer 8

adults 1cm length, brownish, long and thin spicules, well-developed bursa

Question 9

epidemiology in clean pasture

Answer 9

source of contamination for lambs = PPr –> increase around April May –> 3 weeks later –> autoinfection peak/infection peak (eggs released by ewes) –>

Question 10

epidemiology stages in contaminated pasture: sources of contamination

Answer 10

overwintered larvae

Question 11

epidemiology stages in contaminated pasture: sources of contamination

Answer 11

overwintered larvae + PPR

Question 12

epidemiology period in contaminated pasture

Answer 12

earlier peak of infection + peak of number of eggs per gram of feces in the lambs

Question 13

epidemiology period in contaminated pasture

Answer 13

earlier peak of infection + peak of number of eggs per gram of feces in the lambs

Question 14

epidemiology period in contaminated pasture

Answer 14

earlier peak of infection + peak of number of eggs per gram of feces in the lambs –> 2 peaks of infection in lambs

Question 15

EPG proxi for what

Answer 15

parasite count burden –> BUT no accurate measure –> some species don’t lay + eggs of parasites all look identical –> can’t determine species unless look at the epidemiology

Question 16

pathogenesis type 1/type 2

Answer 16

type 1 disease –> late summer, type 2 disease the spring of the following year

Question 17

pathology in abomsaum

Answer 17

rise ph –> abomasum doesn’t function properly, failure to activate pepsinogen into pepsin, increases permeability of gut –> pepsinogen leaks into blood stream –> plasma proteins into abomasum ==> reduced feed consumption and diarrhoea

Question 18

Haemonchus contortus morphological feature

Answer 18

adults 2-3cm, ovary of female coils around intestine, females have barber’s pole barbed spicules,

Question 19

where is haemonchus?

Answer 19

temperate areas, single annual cycle –> eggs deposited by ewes in spring, ingested by lambs in summer, majority arrested

Question 20

haemonchus in sub-tropical areas

Answer 20

several cycles of infection annually, disease outbreaks linked to local rainfall, development resumes just before rainy season

Question 21

pathogenesis of haemonchus

Answer 21

significant loss of blood –> increased RBC turnover, loss of Hb, anf Fe, depleted Fe reserves

Question 22

hyperacute haemonchus disease

Answer 22

death by haemorrhagic gastritis

Question 23

acute disease of haemonchus

Answer 23

1-6 weeks, anaemia, oedema, loss of condition, lethargy

Question 24

chronic disease haemonchus

Answer 24

2 months + –> loss of weight

Question 25

Nematodirus morphological features

Answer 25

adults 2cm, small cephalic vesicle, male fused spicules, eggs larger than strongyles, L3s develop inside egg

Question 26

Nematodirus morphological features

Answer 26

adults 2cm, small cephalic vesicle, male fused spicules, eggs larger than strongyles, EGGS IDENTIFIABLE --> gigantic

Question 27

development of Nematodirsu

Answer 27

L3s develop inside eggshell, PPP ~3 weeks

Question 28

epidemiology of Nematodirus --> periods in the year

Answer 28

L3s develop inside egg --> can survive up to 2 years on pasture (important to implement control strategies) --> hatching when prolonged period of chill + mean day temperature of at least 10°C (late spring)

Question 29

when is disease of Nematodirus present

Answer 29

when large quantities of larvae ingested by lambs

Question 30

when do you see disease of Nematodirus in the year?

Answer 30

three weeks after the conditions have been favourable

Question 31

when is secondary peak of Nematodirus seen?

Answer 31

depending on weather --> 'Indian' summer otherwise --> overwintering until spring

Question 32

pathogenesis of Nematodirus

Answer 32

diarrhoea --> lethargy, high mortality, 2-3 months set-back to growth

Question 33

DIAGNOSIS FOR ALL PARASITES

Answer 33

clinical signs, history, management of flock, PM

Question 34

faecal examination

Answer 34

floatation: parasite eggs float, either qualitative or quantitative, --> McMaster chamber = double slide --> count number of eggs in grade and multiply by dilution factor --> get eggs per gram --> BUT really inaccurate

Question 35

larval culture

Answer 35

requires expertise

Question 36

treatment and control of sheep PGE: what parasite in what order

Answer 36

nematodirus (April) --> Teladorsagia (June) --> Haemonchus (August)

Question 37

problems with all parasites

Answer 37

anthelminthic resistance

Question 38

practices to avoid anthelmintic resistance

Answer 38

new arrivals, sub-therapeutic dosing, high frequency of dosing, insufficient worms in refugia (=worm populations not exposed to drugs)

Question 39

what are refugia?

Answer 39

leave proportion of parasite population untreated --> won't develop resistance --> breed with resistant drug --> dilute genetic pool of resistance

Question 40

how to prevent rise of anthelmintic resistance

Answer 40

test for it, effective quarantine procedures, use anthelmintics sparingly, dose correclty, avoid broad-spectrum anthelmintics, keep worms in refugia to 'dilute' resistant populations = keep 10% of the flock untreated, don't move sheep on clean pasture directly after drenching

Question 41

best drugs for haemonchus

Answer 41

blood feeder --> best drug that has long residual activity and stay in blood

Question 42

prophylaxis by anthelmintics in ewes

Answer 42

management of PPR --> worm ewes around lambing and again 4-5 weeks later,

Question 43

prophylaxis by anthelmintics in lambs

Answer 43

treat at weaning, move to clean pasture, if no alternative grazing available,dose at weaning and repeat at monthly intervals,

Question 44

drug specific for haemonchus

Answer 44

closantel

Question 45

prophylaxis by grazing management plus anthelmintics

Answer 45

one annual anthelmintic treatment of ewes prior to leaving the lambing field --> 3 year rotation with cattle