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*The ''Calliphoridae'' family are '''facultative''' parasites
 
*The ''Calliphoridae'' family are '''facultative''' parasites
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*Cause '''blowfly strike'''
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*Cause <big>[[Blowfly Strike|'''blowfly strike''']]
    
*If the fly lays eggs on an animal, the animal is said to be '''blown'''
 
*If the fly lays eggs on an animal, the animal is said to be '''blown'''
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'''Epidemiology'''
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[[Category:Parasites]][[Category:Flies]][[Category:Myiasis_Producing_Flies]]
<br>Blowflies are divided into categories depending on their ability to initiate strike
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*Primary flies are capable of initiating a strike on living sheep. Larvae can penetrate intact skin
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**''Lucilia''
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**''Phormia''
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**''Calliphora spp.''
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*Secondary flies cannot initiate a strike. Larvae attack an area already struck or damaged, extending it
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**''Calliphora spp.''
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**''Chrysomya spp.'' (in warmer climates)
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*Tertiary flies attack lesions on carcasses which have become dry
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**''Musca''
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**''Sarcophaga spp.''
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Predisposing factors to flystrike
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*Temperature
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**Temperature in the spring will determine when the overwintering larvae hatch
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**High temperature and humidity will create a microclimate in the fleece, attracting adult flies to lay eggs
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*Rainfall
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**Persistent rainfall will make the fleece microclimate attractive to adult flies. Females lay eggs after the rain ceases
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**Breeds with long, fine wool are the most susceptible
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*Host susceptibility
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**This is increased when putrefactive odours develop on the fleece due to bacterial decomposition of organic matter following soiling with urine or faeces
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**Merino sheep have a narrow breech area with excessive wrinkling making them more susceptible to soiling
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**A narrow opening of the penile sheath in rams and wethers may result in accumulation of urine and increase blowfly strike in this area
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**Cuts during shearing, fighting and barbed wire will also increase the incidence of blowfly strike
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Blowfly season
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*Temperate regions in '''June to September'''
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**Mostly in unshorn sheep in June
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**Lambs from July to September
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*Warmer regions have a more prolonged season due to greater number of blowfly generations
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'''Pathogenesis'''
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*Severe skin damage
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**Larvae lacerate skin with oral hooks and liquefy host tissue by secreting proteolytic enzymes
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*Skin lesions are extended and deepened
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**Secondary blowfly attack
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**Flies attracted to odour of decomposing tissue
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*Secondary bacterial infection
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*Production losses
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**Irritation and distress associated with skin lesions
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**Poor weight gain (often the first clinical sign)
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*Risk of strike is highest in warm, moist weather
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'''Clinical signs'''
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*Anorexia
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*Listlessness
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*Animals standing apart from flock
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*Fleece may appear darker, be damp and have a foul smell
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'''Control'''
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*Prophylactic [[Ectoparasiticides|insecticide]] treatment
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**Must kill larvae and remain in fleece to prevent flies from laying eggs
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**Applied by spraying, dipping, spray race or jetting
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*Insect growth regulators
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**Pour-on
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**2-4 month protection depending upon the product used
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*Effective worm control
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**To minimise diarrhoea and therefore soiled fleece
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*Crutching to prevent soiling
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*'Mule's operation'
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**Surgical removal of breech skin in Merino breeds
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*Tail docking of lambs
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*Proper carcass disposal
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**Eliminates fly breeding sites
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*Vaccination
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**Experimental use against ''Luculia cuprina'' in Australia[[Category:Parasites]][[Category:Flies]][[Category:Myiasis_Producing_Flies]]
 
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