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| ==Introduction== | | ==Introduction== |
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| + | Myiasis is the parasitism of living animals by dipteran larvae. Myiasis can be oligatory or facultative (optional) and is described as cutaneous, nasal or somatic. |
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| ==Oestridae== | | ==Oestridae== |
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| + | *The larvae of Oestridae spp. are '''obligatory''' parasites |
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| + | *The three important species of veterinary interest are ''Hypoderma'', ''Oestrus'' and ''Gasterophilus'' |
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| ===''Hypoderma'' spp.=== | | ===''Hypoderma'' spp.=== |
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| *Also known as warble flies | | *Also known as warble flies |
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| + | *Important cattle parasites |
| + | **Also parasitise horses, small ruminants and sometimes humans |
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| + | *The two main species in cattle are ''H. bovis'' and ''H. lineatum'' |
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| + | *''H. diana'' parasitises deer |
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| + | *Infestation is largely confined to the Northern Hemisphere |
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| '''Recognition''' | | '''Recognition''' |
| + | *Large 13-15mm long |
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| + | *Similar to bumble bees in appearance |
| + | **Yellow abdomen |
| + | *Band of black hairs |
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| + | *One pair of wings |
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| '''Life Cycle''' | | '''Life Cycle''' |
| + | *Adult flies emerge on warm, sunny days between June and August |
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| + | *White eggs are laid around the belly and legs of the animal |
| + | **Eggs are attached to hairs by cement and a small terminal clasp |
| + | **''H. lineatum'' lays a whole row of eggs as it approaches the animal stealthily |
| + | **''H. bovis'' only deposits a single egg before the animal runs away (''''gadding''') as it makes a loud buzzing noise |
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| + | *The adult lives for 3 weeks |
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| + | *Females can lay several hundred eggs in their life |
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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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| + | *Larvae penetrate the skin through wounds made by [[Biting Flies - WikiBlood|biting flies]] |
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| + | *Larvae migrate through the subcutaneous tissue towards the diaphragm |
| + | **Enzymatic secretions and mouth hooks aids larval migration |
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| + | *After 3 months larvae reach '''winter resting sites''' where they remain from November to Feburary/March whilst moulting to the L2 stage |
| + | **Epidural fat in the spinal canal for ''H. bovis'' |
| + | **Wall of the oesophagus for ''H. lineatum'' |
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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 |
| + | **Larvae are palpable as distinct swellings called '''warbles''' |
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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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| + | *Adult flies emerge from the pupa after one month where they copulate, lay eggs and die within two weeks |
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| + | *''H. lineatum'' are on the wing 6-8 weeks before ''H. bovis'' |
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| + | *There is only '''one''' generation of warble flies per year |
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| '''Pathogenesis''' | | '''Pathogenesis''' |