Trichostrongyloidea 3 Ostertagia, T. axei

Question 1

What is common name for Ostertagia, species it infects, preferred site within host

Answer 1

brown stomach worm
sheep, goat, cattle
abomasum

Question 2

Where do ostertagia principally occur (region)

Answer 2

southern australia- high rainfall areas

Question 3

Where does L3 ostertagia occur in the host

Answer 3

L3 exsheaths in rumen, migrates to gastric gland to molt->L4
LUMEN OF THE ABOMASAL GLANDS
L3 is resistant and may survive over summer in fecal pellet

Question 4

What is the PPP of ostertagia

Answer 4

18-21 days

Question 5

Does hypobiosis occur with ostertagia

Answer 5

hypobiosis is common (6 months)

Question 6

When does inhibition occur in ostertagia

Answer 6

inhibition occurs in the spring, emerge in autumn- summer weather too harsh for survival

Question 7

Pathogenesis: what does migration of ostertagia larvae into the abomasal glands cause

Answer 7

hyperplasia and metaplasia (nodules) of gland cells, necrosis of gland cells occurs in areas of direct contact with larvae

Question 8

Ostertagia cause hyperplasia and metaplasia of abomasal gland cells what does this lead to

Answer 8

reduction in number of acid (parietal) and pepsin secreting (cheif) cells in the abomasum->mucus secreting cells predominate and stomach pH rises

Question 9

What will you grossly see in the abomasum with infection of Ostertagia

Answer 9

areas of cell hyperplasia (raised pin point white foci), around pylorus and maybe in folds of fundus (heavy infection)

Question 10

Why is digestion of food impaired in ostertagia infection

Answer 10

pepsinogen is not converted to pepsin at high pH

Question 11

Why do the pepsinogen concentrations in blood rise with ostertagia infection

Answer 11

increased secretion and greater mucosal permeability

Question 12

What does ostertagia secrete that leads to increased gut motility->diarrhea

Answer 12

parasympathomimetic substances

Question 13

What are the different species of Ostertagia and what host do they infect

Answer 13

O. circumcincta- sheep
O. trifurcata- sheep
Teladorsagia davtiana- sheep
O. ostertagi- cattle

Question 14

what is the most important parasite of cattle in southern Australia (temperate areas)

Answer 14

Ostertagia ostertagi

Question 15

What are 3 defining features of Ostertagia

Answer 15

• cervical papillae
• spicules terminate in 3 stubby hooked
processes
• small vulval flap

Question 16

host immunity against ostertagia

Answer 16

develops in older animals and stunts worms->fewer eggs produced

Question 17

What are 2 differences of ostertagia in sheep and O.ostertagi in cattle

Answer 17

1. Faecal mass as a reservoir for larvae

2. Inhibited larvae can emerge synchronously

Question 18

What larval stage of ostertagia can survive for long periods in a cattle dung patty

Answer 18

L3

Question 19

Explain type 1 ostertagiasis in cattle infected with ostertagia ostertagi

Answer 19

• young animals
• no immunity
• occurs in spring
• diagnose with egg counts, plasma
pepsinogen
- similar to what is seen in sheep

Question 20

Explain type 2 ostertagiasis in cattle infected with ostertagia ostertagi

Answer 20

• larvae emerge synchronously
• 2-4 year old animals
• precipitated by “stress” (calving)
• erratic in occurrence (some years, few
cattle affected)
• occurs in autumn
• diagnose with plasma pepsinogen

Question 21

What is the common name for Trichostrongylus axei, where does it occur in host and what species does it infect

Answer 21

stomach hairworm
abomasum
sheep, cattle, horse, pig, man

Question 22

What does T axei do to the host

Answer 22

causes disruption of the epith, loss of plasma proteins into abomasum->pH risees and excess mucus produced

Question 23

how many T axei can kill a lamb and why is this so

Answer 23

40,000 can kill because they are highly pathogenic

Question 24

Because of T axei host range what

Answer 24

they are important to consider in mixed grazing situations