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Ostertagiosis and Trichostrongylosis - Sheep (view source)
Revision as of 21:47, 21 April 2010
, 21:47, 21 April 2010Created page with '==Ostertagiosis and Trichostrongylosis== ==== Parasites ==== ''Ostertagia'' species (abomasum) are responsible for outbreaks of clinical ostertagiosis in lambs; different specie…'
==Ostertagiosis and Trichostrongylosis==
==== Parasites ====
''Ostertagia'' species (abomasum) are responsible for outbreaks of clinical ostertagiosis in lambs; different species are found in sheep and cattle, but the life-cycle and pathogenesis are very similar. ''Trichostrongylus'' species found in the abomasum and small intestine also contribute to or may even cause ovine [[Parasitic Gastroenteritis|PGE]].
==== Forms of Ovine Ostertagiosis and Trichostrongylosis ====
'''Type 1 Ostertagiosis''' (the predominant from of PGE in sheep)
*Mainly caused by ''O. circumcincta''
*Affects lambs during first grazing season ('''July - September''')
*Clinical signs
**Diarrhoea
**Weight loss
**Reduced appetite
'''Type 2 Ostertagiosis'''
*Affects lambs >1 year old after first grazing season ('''January - May''')
*Clinical signs
**Progressive weight loss
**Intermittent diarrhoea
'''Trichostrongylosis'''
*Caused by ''Trichostrongylus axei'' (abomasum) and ''Trichostrongylus'' species (small intestine)
*Affects lambs <1 year old towards the end of the first grazing season ('''November - December''')
*Clinical signs
**Dark foul-smelling diarrhoea ("black scour")
**Weight loss
==== Epidemiology of Ovine Ostertagiosis - Periparturient Relaxation in Immunity (PPRI) ====
*Affects mainly breeding ewes but can also affect non-breeding animals (barren ewes and rams)
*Impaired immunity because of:
#PPRI (breeding ewes only)
#Poor plane of nutrition
#Management (winter housing reduces antigenic stimulation)
*Increased worm egg output because:
#Increased establishment of L3
#Increased egg production per female worm
#Resumed development of arrested larvae
==== Epidemiology of Ovine Ostertagiosis on clean and contaminated pasture ====
'''Clean Pasture'''
*'''EE''': Ewes' periparturient ("spring") rise in faecal egg count
*'''AP''': Autoinfection peak in L3, from (EE)
*'''LE''': Lamb faecal egg count, from (AP); and
*'''AP2''': Second peak in L3, from (LE)
'''Contaminated Pasture'''
*'''OW''': Overwintered L3 on pasture
*'''EE''': Ewes' periparturient ("spring") rise in faecal egg count
*'''LE''': Lamb faecal egg count, from (OW) (no disease)
*'''AP''': Autoinfection peak in L3, from (EE) and (LE)
*'''LE2''': Lamb faecal egg count, from (AP); and
*'''AP2''': Second peak in L3, from (LE2)
==== Diagnosis of Ovine Ostertagiosis and Trichostrongylosis ====
*Clinical signs
*Season
*Faecal egg count:
**High in Type 1 ostertagiosis and trichostrongylosis
**Variable in Type 2 ostertagiosis
*Blood pepsinogen:
**Elevated in ostertagiosis only, unless large ''Trichostrongylus axei'' burden
*Post-mortem examination:
**Ostertagiosis:
***Hyperplastic nodules
***Raised gastric pH
***>10,000 adult worms
***Large numbers of arrested larvae (Type 2 disease only)
**Trichostrongylosis:
***Severe enteritis
***>30,000 adult worms
[[Category:Sheep]][[Category:Trichostrongyloidea]]
==== Parasites ====
''Ostertagia'' species (abomasum) are responsible for outbreaks of clinical ostertagiosis in lambs; different species are found in sheep and cattle, but the life-cycle and pathogenesis are very similar. ''Trichostrongylus'' species found in the abomasum and small intestine also contribute to or may even cause ovine [[Parasitic Gastroenteritis|PGE]].
==== Forms of Ovine Ostertagiosis and Trichostrongylosis ====
'''Type 1 Ostertagiosis''' (the predominant from of PGE in sheep)
*Mainly caused by ''O. circumcincta''
*Affects lambs during first grazing season ('''July - September''')
*Clinical signs
**Diarrhoea
**Weight loss
**Reduced appetite
'''Type 2 Ostertagiosis'''
*Affects lambs >1 year old after first grazing season ('''January - May''')
*Clinical signs
**Progressive weight loss
**Intermittent diarrhoea
'''Trichostrongylosis'''
*Caused by ''Trichostrongylus axei'' (abomasum) and ''Trichostrongylus'' species (small intestine)
*Affects lambs <1 year old towards the end of the first grazing season ('''November - December''')
*Clinical signs
**Dark foul-smelling diarrhoea ("black scour")
**Weight loss
==== Epidemiology of Ovine Ostertagiosis - Periparturient Relaxation in Immunity (PPRI) ====
*Affects mainly breeding ewes but can also affect non-breeding animals (barren ewes and rams)
*Impaired immunity because of:
#PPRI (breeding ewes only)
#Poor plane of nutrition
#Management (winter housing reduces antigenic stimulation)
*Increased worm egg output because:
#Increased establishment of L3
#Increased egg production per female worm
#Resumed development of arrested larvae
==== Epidemiology of Ovine Ostertagiosis on clean and contaminated pasture ====
'''Clean Pasture'''
*'''EE''': Ewes' periparturient ("spring") rise in faecal egg count
*'''AP''': Autoinfection peak in L3, from (EE)
*'''LE''': Lamb faecal egg count, from (AP); and
*'''AP2''': Second peak in L3, from (LE)
'''Contaminated Pasture'''
*'''OW''': Overwintered L3 on pasture
*'''EE''': Ewes' periparturient ("spring") rise in faecal egg count
*'''LE''': Lamb faecal egg count, from (OW) (no disease)
*'''AP''': Autoinfection peak in L3, from (EE) and (LE)
*'''LE2''': Lamb faecal egg count, from (AP); and
*'''AP2''': Second peak in L3, from (LE2)
==== Diagnosis of Ovine Ostertagiosis and Trichostrongylosis ====
*Clinical signs
*Season
*Faecal egg count:
**High in Type 1 ostertagiosis and trichostrongylosis
**Variable in Type 2 ostertagiosis
*Blood pepsinogen:
**Elevated in ostertagiosis only, unless large ''Trichostrongylus axei'' burden
*Post-mortem examination:
**Ostertagiosis:
***Hyperplastic nodules
***Raised gastric pH
***>10,000 adult worms
***Large numbers of arrested larvae (Type 2 disease only)
**Trichostrongylosis:
***Severe enteritis
***>30,000 adult worms
[[Category:Sheep]][[Category:Trichostrongyloidea]]