Strongyloidea - pigs

Question 1

Where is the site of infection of Oesophagostomum spp in pigs?

What is the life cycle?

Answer 1

• LI
• Direct
• L3 infective (not in egg)
• PPP ~3 weeks
• Adults in LI pass eggs
• Development from L1 to L3 in environment, and ingestion of L3
• L3 enters SI or LI mucosa
• nodules may be induced
• EL4 possible in nodules
• L4 emerge and adults mature in LI

Question 2

Are infections of Oesophagostomum more prevelent in young or old pigs? Indoor or outdoor?

Answer 2

• Older pigs - infection accumulates with age
• Mainly outdoor, but can complete their life cycle indoors
• In this sense, diagnosis can be made on FEC due to it being the only other parasite present in intensive indoor production systems, ans is easily differentiated from Ascaris suis eggs. However, the egg is similar to Hyostrongylus so differentiation on outdoor systems is more difficult.

Question 3

As the pig ages and its acquired immunity increases, what happens with worm burden?

Why is this important?

Answer 3

• Increasing numbers of larva remain arrested in nodules
• Larva in nodules are not susceptible to anthelmintics
• There is a rise in fecal egg output in the periparturient time
• Piglets are therefore born into a highly infected environment
• Prevention can be attained by one dose of anthelmintic a week before farrowing

Question 4

What is the pathology of Oesophagostomum and what are some clinical signs?

Answer 4

• Diffuse enteritis in colon and cecum with distinct **nodules **(in some spp)
• Acute infections - hemorrhage and secondary infection
• Chronic infections - fibrous nodules
• Reduced productivity
  
  • reduced weight gain in growing pigs
  • poor milk yields, “thin sow syndrome”, and possibly fertility problems in sows
• Diarhea in very heavy infections