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Also Known As: '''''Fly-Strike — Wound Myiasis — Maggots — Strike — Fly Infestation — Wool Maggots'''''
Caused By: '''[[Myiasis Producing Flies]]'''
==Pathogenesis==
==Introduction==
[[File:Myiasis cat.jpg|thumb|200px|right|Cat with myiasis. Wikimedia Commons]]
[[File:Gasterophilus larvae.jpg|thumb|200px|right|Larval form of ''Gasterophilus spp'' stomach botfly. Wikimedia Commons]]
Myiasis is caused by infestation of live hosts with '''[[Biting Flies |dipterous larvae]]'''. Small and large ruminants and poultry can be affected. These larvae then feed on the host’s living and dead tissue.
[[Myiasis Producing Flies]] can be '''obligate or facultative'''.
==Myiasis Causing Flies==
===Obligate===
'''Obligate flies''' occur exclusively '''in '''or''' on''' living vertebrates.
''[[Oestrus ovis]]'', [[Gasterophilus spp.|''Gasterophilus'' spp.]], [[Hypoderma spp.|''Hypoderma'' spp.]], [[Dermatobia hominis |''Dermatobia ''spp]], [[Wohlfahrtia spp.|''Wohlfahrtia'' spp.]], ''Cochliomyia, [[Chrysomya bezziana]]'' and ''Cordylobia.''
===Facultative===
'''Facultative''' flies are '''free-living''' and usually found in detritus or carrion.
''Cochliomyia macellaria, Chrysomya megacephala, rufifacies'' and ''albiceps, Lucilla sericata'' and cuprina, Phormia ''spp., ''Protophormia ''spp. and ''Caliphora'' spp.
For more information, see [[Myiasis Producing Flies]].
==Distribution==
[[Myiasis Producing Flies]] are found in most regions of the world.
==Signalment==
Presence of '''wounds, wet fleece''' in sheep cases, recent '''surgery''', bacterial wool/skin contamination and '''faecal contamination''' are the main predisposing factors for myiasis.
Density of stock will determine size and viability of the fly population.
==Clinical Signs==
Can be classified as '''cutaneous, nasopharyngeal, intestinal''' or '''urogenital'''. '''Pain, irritation, discomfort, alopecia''' and '''pruritus''' are common signs locally. There is also likely to be '''direct tissue damage, haemorrhage''', hyperpigmentation and secondary infection.
[[Oestrus ovis |'''Nasal myiasis''']] causes irritation and [[Epistaxis |epistaxis]].
'''Aural myiasis''' can cause deafness, discharge and foul exudates.
'''Gastrointestinal myiasis''' caused by [[Gasterophilus spp.|''Gasterophilus'' spp.]] often causes '''ulceration, GI bleeding''', weight loss, [[Diarrhoea |diarrhoea]] and pupae are voided in faeces.
[[Hypoderma spp. |'''Warble flies''']] cause '''cysts''' along the midline of the '''back'''.
''Lucilia sericata'' tends to cause lesions on the inner '''thighs and perineum''' due to faecal soiling.
''[[Wohlfahrtia spp.|''Wohlfahrtia' spp.]]'' cause '''genital lesions''' on the vulva and prepuce.
'''Loss of feathers''' and soiling of the vent is seen in '''poultry'''.
In severe cases, anaemia, anaphylaxis and toxaemia may be fatal. Likely consequence is reduced feeding and resulting weight loss and infertility.
==Diagnosis==
Diagnosis is primarily dependent on '''observation of larvae''' on the host or in the faeces.
Larvae may also be observed in the carcass at '''post-mortem'''.
Gastroscopy may be used in the case of [[Gasterophilus spp. |gastric myiasis]].
'''[[ELISA testing | ELISA]]''' is also available for [[Hypoderma spp.|''Hypoderma'' spp.]] and ''[[Oestrus ovis]]''. '''PCR''' is available for ''Cochliomyia spp''.
==Treatment==
Treatment with '''[[Ectoparasiticides |ectoparasiticides]]''' is usually effective. Administration can be '''oral, topical or by subcutaneous injection''' and the type of myiasis should be considered when deciding upon route of administration.
'''Ivermectin''' and '''doramectin''' are both effective in the control of [[Oestrus ovis |nasal myiasis]] ,[[Hypoderma spp. |warble fly]] and [[Dermatobia hominis |''Dermatobia'']] when '''injected'''.
'''Moxidectin''' is the main drug for '''oral treatment'''. It is effective against [[Gasterophilus spp.|''Gasterophilus'' spp.]]
'''Topical treatment''' by '''pour-on or dipping''' is most effective against '''cutaneous/subcutaneous myiasis'''. A huge range of products are available. Resistance should be considered and monitored.
==Control==
==Control==
Preventative treatment with '''[[Ectoparasiticides |ectoparasiticides]]''' is common.
Release of '''sterile insects''' is also possible and effective but expensive.
'''[[Vaccines]]''' are available against [[Hypoderma spp.|''Hypoderma ''spp.]] and ''Lucilia spp.''
<b><big>Also see [[Cutaneous Blowfly Myiasis – Rabbit|Myiasis in Rabbits]]</big></b>
{{Learning
|flashcards = [[Myiasis Flashcards]]
}}
{{Chapter}}
{{Mansonchapter
|chapterlink = http://www.mansonpublishing.co.uk/book-images/9781840760491_sample.pdf
|chaptername = Cutaneous Myiasis
|book = Sheep Medicine
|author = Philip R. Scott
|isbn = 9781840761498
}}
==References==
<references/>
{{CABI source
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=74573&loadmodule=datasheet&page=2144&site=160 myiasis-causing flies]
|date =6 June 2011
}}
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[[Category:Integumentary System - Parasitic Infections]]
[[Category:Integumentary System - Parasitic Infections]]
[[Category:To_Do_-_Dermatology]]
[[Category:CABI Expert Review]][[Category:CABI AHPC Pages]]