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| | **''Gasterophilus'' | | **''Gasterophilus'' |
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| | + | <big> |
| | + | '''[[Hypoderma spp.|''Hypoderma spp.'']] |
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| − | ===''Hypoderma spp.''===
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| − |
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| − | *Also known as warble flies
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| − |
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| − | *Important cattle parasites
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| − | **Also parasitise horses, small ruminants and sometimes humans
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| − |
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| − | *The two main species in cattle are
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| − | **''H. bovis''
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| − | **''H. lineatum''
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| − |
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| − | *''H. diana'' parasitises deer
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| − |
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| − | *Infestation is largely confined to the Northern Hemisphere
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| − |
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| − |
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| − | '''Recognition'''
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| − | *Large 13-15mm long
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| − |
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| − | *Similar to bumble bees in appearance
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| − | **Yellow abdomen
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| − | **Band of black hairs
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| − |
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| − | *1 pair of wings
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| − |
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| − |
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| − | '''Life cycle'''
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| − | *Adult flies emerge on warm, sunny days between '''June and August'''
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| − |
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| − | *White eggs are laid around the belly and legs of the animal
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| − | **Eggs are attached to hairs by cement and a small terminal clasp
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| − | **''H. lineatum'' lays a whole row of eggs as it approaches the animal stealthily
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| − | **''H. bovis'' only deposits a single egg before the animal runs away ('''gadding''') as it makes a loud buzzing noise
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| − |
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| − | *The adult lives for 3 weeks
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| − |
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| − | *Females can lay several hundred eggs in their life
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| − |
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| − | *A few days after eggs are laid, larvae emerge and crawl down the hairs into the hair follicles
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| − |
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| − | *Larvae penetrate the skin through wounds made by [[Biting Flies|biting flies]]
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| − |
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| − | *Larvae migrate through the subcutaneous tissue towards the diaphragm
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| − | **Enzymatic secretions and mouth hooks aid larval migration
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| − |
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| − | *After 3 months larvae reach '''winter resting sites''' where they remain from November to February/March whilst moulting to the L2 stage. These sites are different between the 2 species
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| − | **Epidural fat in the spinal canal for ''H. bovis''
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| − | **Wall of the [[Oesophagus - Anatomy & Physiology|oesophagus]] for ''H. lineatum''
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| − |
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| − | *Larvae then migrate back to the subcutis along the midline of the back where they bore a breathing hole through the skin and moult to the L3 stage
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| − | **Larvae are palpable as distinct swellings called '''warbles'''
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| − |
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| − | *L3 larvae emerge after 4-10 weeks where they fall to the ground and pupate under loose vegetation
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| − |
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| − | *Adult flies emerge from the pupa after 1 month where they copulate, lay eggs and die within 2 weeks
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| − |
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| − | *''H. lineatum'' are on the wing 6-8 weeks before ''H. bovis''
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| − |
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| − | *There is only '''1 generation''' of warble flies per year
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| − |
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| − |
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| − | '''Pathogenesis'''
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| − | *Causes [[Muscles Inflammatory - Pathology#Arthropods|myositis]]
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| − |
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| − | *Production losses
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| − | **Condemnation and down-grading of hides
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| − | **Reduced milk yield and reduced weight gain
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| − | **Injury from stock panic
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| − | **Trimmed meat losses from ''H. lineatum''
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| − | ***'Butcher's Jelly' around warbles which is green due to mass [[Eosinophils - WikiBlood|eosinophil]] attraction
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| − |
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| − | *Paraplegia resulting from
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| − | **Toxin release
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| − | **Pressure on the spinal cord (''H. bovis'')
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| − | **Bloat from pressure on the [[Oesophagus - Anatomy & Physiology|oesophageal wall]] (''H. lineatum'')
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| − |
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| − |
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| − | '''Control'''
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| − | *Total eradication should be aimed for
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| − |
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| − | *Old methods include popping out warbles
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| − | **But this could lead to anaphylactic shock
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| − |
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| − | *[[Ectoparasiticides]]
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| − | **Systemic organophosphorus [[Ectoparasiticides|insecticides]] in pour-on formula
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| − | **Avermectins and milbemycins in pour-on and injectible formulations
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| − |
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| − | *Timing is crucial for treatment
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| − | **Larvae residing in winter resting sites, if killed, can lead to bloat and paraplegia
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| − | **It is safe to treat in the '''autumn''' before larvae reach their winter resting sites and in the '''spring''' when the warbles have migrated to the midline of the back
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| − | **Ivermectin can be given at any time without risking host infection as larval antigen is released much slower
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| − |
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| − |
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| − | '''Legislation in the UK'''
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| − | *'Warble Fly Order 1978' requires all clinically affected animals to be treated
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| − | *Notifiable disease
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| − |
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| − | *'Warble Fly Infected Area Order 1983'
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| − |
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| − | *For more information on the warble fly orders, see [http://www.defra.gov.uk/animalh/diseases/notifiable/brucellosis/surveillance.htm| here]
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| | + | </big> |
| | ===''Oestrus ovis''=== | | ===''Oestrus ovis''=== |
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