Nematode and cestode infections in sheep

Question 1

What are current problems with parasite control in sheep?

Answer 1

• Drug resistance
• Climate change
• Parasites - large genomes

Question 2

What are common nematode infections in sheep?

Answer 2

• Nematodirus battus
• Teladorsagia circumcincta
• Trichostrongylus vitrinus
• Haemonchus contortus
• Dictyocaulus filaria

Question 3

How do worms cause disease?

Answer 3

• Damage lining of guts
• Remove nutrients
• Remove blood
• Host immune response

Question 4

What are clinical signs of nematode infection?

Answer 4

• Reduced appetite
• Poor weight gain
• Diarrhoea
• Anaemia
• Death

Question 5

What are the disease caused by nematodes?

Answer 5

• Nematodirus battus - acute severe diarrhoea + death in lambs 6-12weeks
• Teladorsagia - type 1 lambs first graing season mid summer
  -type 2 yearlings in winter months
• Trichostronygus - black scour
• Haemonchus contortus - adults + lambs, acute regeneratuve anaemia + bottle jaw

Question 6

What is the nematode life cycle?

Answer 6

• L1 + L2 live in faeces
• L3 infective stage - migrates to pasture
• Develops to eggs in sheep - 16-21days

Question 7

When do different species of worm peak?

Answer 7

• Teladorsagia - early summer
• Trichostrongylus - late summer / autumn
• Haemonchus - mid spring, late autumn

Question 8

What is hypobiosis?

Answer 8

L3 late autumn early winter over winter period interupted development L4 stage inside sheep.
◦ Teladorsagia- clinical disease scouring and weight loss in yearling sheep
◦ Pasture contamination in spring and early summer
◦ Main way Haemonchus survives winter

Question 9

How can you increase risk of resistance?

Answer 9

• Treatment frequency
• Proportion of population exposed to treatment in refugia
• Under dosinng
• Biosecurity - new strains

Question 10

How can you test for anthelmintic resistance?

Answer 10

• FECRT

Question 11

When should you worm adult sheep?

Answer 11

• Treat at lambing time - to reduce pasture contamination for lambs - leave portion untreated (Fit singles)
• Treat thin ewes at tupping time

Question 12

What are tapeworms found in sheep?

Answer 12

• Monezia
• Taenia hydatigena
• Taenia ovis
• Taenia multiceps
• Echinococcus granulosus