Parasites (Yr3)

Question 1

what are nematodes also known as?

Answer 1

roundworms

Question 2

what are platyhelminths also known as?

Answer 2

cestodes and trematodes

Question 3

what are trematodes also known as?

Answer 3

fluke

Question 4

what are cestodes also known as?

Answer 4

tapeworm

Question 5

what is the feeding stage of protozoa called?

Answer 5

trophozoite

Question 6

what does Ostertagia ostertagi cause in cattle?

Answer 6

PGE

Question 7

where is Ostertagia ostertagi found in cattle?

Answer 7

abomasum

Question 8

what type of lifecycle does Ostertagia ostertagi have?

Answer 8

typical trichostrongyle (trichostrongyle eggs)

Question 9

what happens to Ostertagia ostertagi once L3 is ingested?

Answer 9

reaches abomasum and burrows into gastric gland where it develops to L5 and emerges into the lumen and mature to lay eggs

Question 10

what is the pathogenesis of Ostertagia ostertagi?

Answer 10

L5 damages gastric glands (parietal cells replaced by epithelial) leading to loss of acid production
this reduces the bacteriostatic effect and less pepsinogen is converted to pepsin making the mucosa more permeable

Question 11

what animals is type I ostertagiosis seen in?

Answer 11

dairy replacement calves towards the end of the first grazing season (July-September), most of the group will be effected

Question 12

what causes type I ostertagiosis?

Answer 12

ingestion of large numbers of L3 in July (green watery diarrhoea)

Question 13

what causes type II ostertagiosis?

Answer 13

mass emergence from hypobiosed larvae from the gastric glands in late winter/early spring

Question 14

when is type II ostertagiosis seen?

Answer 14

late winter/early spring in yearling calves (mass emergence of hypobiosed larvae)

Question 15

what is the main pathogen causing PGE in cattle?

Answer 15

Ostertagia ostertagi

Question 16

what nematodes are found in the abomasum of cattle?

Answer 16

Haemonchus contortus
Ostertagia ostertagi
Trichostrongylus axei

Question 17

what nematodes are found in the small intestine of cattle?

Answer 17

Nematodirus spp.
Trichostrongylus spp.
Cooperia spp.

Question 18

what factors affect the development of the pre-parasitic stages of Ostertagia ostertagi?

Answer 18

temperature (>10°C)
humidity
dispersal from faecal pat (rainfall)

Question 19

what factors effect the survival of Ostertagia ostertagi L3?

Answer 19

ensheathed (wears L2 cuticle)
temperature (hates heat)
moisture (desiccation is lethal)
limited food reserve = limited survival

Question 20

what stage of the lifecycle undergoes hypobiosis?

Answer 20

L4 (in the gastric gland)

Question 21

where will the L3 causing type I ostertagiosis come from?

Answer 21

L3 overwintering on pasture used the previous year

Question 22

when does the amount of Ostertagia ostertagi eggs peak on pasture?

Answer 22

July - meaning outbreaks will occur around three weeks after this due to the pre-patent period

Question 23

why are beef calves less likely to get ostertagiosis?

Answer 23

grazed with immune mothers (autumn born calves may encounter it in the spring when turned out)

Question 24

what can be used for definitive diagnosis of Ostertagia ostertagi?

Answer 24

raised plasma pepsinogen levels
(clinical signs, grazing history, season)

Question 25

what is clean pasture?

Answer 25

pasture not grazed by cattle for last 12 months

Question 26

what is safe pasture?

Answer 26

pasture used previous year but safe by June

Question 27

what is the typical treatment strategy for Ostertagia ostertagi?

Answer 27

treat first season grazing calves 3 weeks post-turnout with ivermectin to prevent egg shedding
treat again 5 weeks later (due to ivermectins 2 week residual activity)
overwintered larvae should have died off by then so no more treatment required

Question 28

if using a strategic worming control strategy for Ostertagia ostertagi, when should you treat?

Answer 28

when FEC >200e/g

Question 29

do spring born suckler calves need treating for Ostertagia ostertagi?

Answer 29

mothers will pick up majority if worm burden when grazing but treat at housing to prevent type II

Question 30

does Dictyocaulus viviparous have an intermediate host?

Answer 30

no, it has a direct lifecycle

Question 31

what is the lifecycle of Dictyocaulus viviparous?

Answer 31

L1 coughed up, swallowed and excreted in faeces
L1 moults to L3 which is ingested
lympho-tracheal migration moulting to L4 in lymph nodes (penetration phase)
L4 moults to L5 in lungs and migrates to trachea/bronchus (pre-patent phase)
adults lay eggs that hatch and to L1 (patent phase)
adults are expelled and protective immunity acquired (post-patent phase)

Question 32

what are the most pathogenic stages of Dictyocaulus viviparous?

Answer 32

pre-patent and patent

Question 33

what pathology can be seen in the post-patent phase?

Answer 33

lung tissue can epithelialise and scar which may never recover

Question 34

what factors effect the pre-parasitic stages of Dictyocaulus viviparous development?

Answer 34

temperature
moisture
dispersal (pilobolus fungi)

Question 35

can Dictyocaulus viviparous overwinter?

Answer 35

yes

Question 36

when is disease caused by Dictyocaulus viviparous seen?

Answer 36

August/September in dairy replacement calves

Question 37

how can Dictyocaulus viviparous be diagnosed?

Answer 37

baermann (L1 in faeces)
antibody ELISA
clinical signs/season

Question 38

can animals become immune to Dictyocaulus viviparous?

Answer 38

no, immunity is short lived

Question 39

what is the vaccination protocol for Dictyocaulus viviparous?

Answer 39

two doses, four weeks apart before turnout