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| '''Epidemiology''' | | '''Epidemiology''' |
| + | *Divided into categories depending on their ability to initiate strike |
| + | **Primary flies are capable of initiating a strike on living sheep so larvae can penetrate intact skin |
| + | ***E.g. ''Lucilla'', ''Phormia'' and ''Calliphora'' |
| + | **Secondary flies cannot initiate a strike, larvae attack an area already struck or damaged, extending it |
| + | ***E.g. ''Callipohora'' and ''Chrysoma'' (in warmer climates) |
| + | **Tertiary flies attack lesions on carcasses which have become dry |
| + | ***E.g. ''Musca'' and ''Sarcophaga'' spp. |
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| + | *Temperature will affect the prevalence of strike |
| + | **Temperature in the spring will determine when the overwintering larvae hatch |
| + | **High temperature and humidity will create a microclimate in the fleece, attracting adult flies to lay eggs |
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| + | *Persistent rainfall will make the fleece microclimate attractive to adult flies |
| + | **Females lay eggs after the rain ceases |
| + | **Breeds with long, fine wool are the most susceptible |
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| + | *Host susceptibility is increased when putrefactive odours develop on the fleece due to bacterial decomposition of organic matter |
| + | **Merino sheep have a narrow breach area with excessive wrinkling making them more suceptible to soiling |
| + | **A narrow opening of the penile sheath in rams and wethers may result in accumulation of urine and increase blowfly strike in this area |
| + | **Cuts during shearing, fighting and barbed wire will also increase the incidence of blowfly strike |
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| '''Pathogenesis''' | | '''Pathogenesis''' |