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| | + | *Harvest mite infestation (chiggers) - [[Trombicula autumnalis|''Trombicula'' sp.]] |
| | + | *Form tunnels in epidermis by injecting saliva - eat digested tissue fluid |
| | + | *Intense pruritus |
| | + | *Grossly: |
| | + | **Small, red [[Skin Glossary - Pathology|papules or crusts]] |
| | + | **Orange to red larvae |
| | + | **On skin close to plants or the ground |
| | + | *Microscopically: |
| | + | **Hyperplastic, superficial perivascular dermatitis |
| | + | **[[Eosinophils|Eosinophils]], [[Mast Cells|mast cells]] |
| | + | **Intraepidermal mites |
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| − | {{Taxobox
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| − | |name = ''Trombicula autumnalis''
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| − | |phylum = [[:Category:Arthropods|Arthropoda]]
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| − | |class = [[:Category:Arachnida|Arachnida]]
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| − | |order = Trombidiformes
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| − | |family = Trombiculidae
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| − | |genus = Trombicula
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| − | |species = ''T.autumnalis''
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| − | }}
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| − | Caused by: '''''Trombicula autumnalis ''''' also known as: '''''Harvest mite — Neotrombicula autumnalis — Chiggers'''''
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| − | ==Introduction==
| + | [[Category:Integumentary System - Mite Infections]] |
| − | [[File:harvest mite1.jpg|thumb|200px|right|''Trombicula mite bites'' Tim Vickers 2008, wikimedia commons]]
| + | [[Category:To_Do_-_Clinical]] |
| − | ''Trombicula autumnalis'' are [[Non-Burrowing Mites|surface mites]] found worldwide. It will attack and parasitise '''any''' animal including humans, causing parasitic skin infestation (trombiculidiasis). Only the larval stage is parasitic however, and adult mites are found living in the soil.
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| − | ==Identification==
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| − | The mites are bright orange in colour and hairy. They have six legs and no spiracles. They breathe through their cuticle.
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| − | ==Lifecycle==
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| − | The lifecycle of ''Trombicula autumnalis'' mites lasts around 50 to 70 days. The nymphal and adult stages are free-living in the soil. Eggs are laid in soil and once hatched, larvae climb up vegetation in search of a host to attach to. As the name suggests, numbers are greatest in 'harvest' time, late summer, in temperate climates and all year round in the tropics.
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| − | ==Pathogenesis==
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| − | The larvae insert their mouthparts into the host's skin and inject cytolytic enzymes. They then feed on partly digested host tissue causing irritation and potentially a [[:Category:Hypersensitivity|hypersensitivity reaction]].
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| − | The Mites are mainly found on the head, ears and flanks of pets and can be found on the face and limbs of grazing animals, depending upon the host height.
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| − | == Clinical Signs ==
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| − | The animal will show signs of intense pruritus and orange to red coloured larvae may be visible on the skin. There will be a erythematous, papular rash and also crusting and scaling.
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| − | == Diagnosis ==
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| − | Clinical signs and the time of year is indicative of the parasite. On physical examination, it is likely the parasite will be seen. Skin scraping, coat brushing or a tape strip may reveal the presence of the mite. Microscopically, the skin will appear hyperplastic with superficial perivascular dermatitis and the presence of [[eosinophils]] and [[Mast Cells|mast cells]].
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| − | == Treatment and Control ==
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| − | Treat infected animals with a licensed acaracide. Control is almost impossible, if animal has a known hypersensitivty reaction then try to avoid affected areas ('hot-spot') during the season.
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| − | {{Learning
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| − | |literature search = [http://www.cabdirect.org/search.html?q=title:(%22Trombicula+autumnalis%22)+ ''Trombicula autumnalis'' publications]
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| − | |Vetstream = [https://www.vetstream.com/canis/search?s=mite Mites]
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| − | }}
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| − | == References ==
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| − | Brown, C.M, Bertone, J.J. (2002) '''The 5-Minute Veterinary Consult- Equine''''', Lippincott, Williams & Wilkins''
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| − | Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary '''(2nd Edition) ''Elsevier Science''
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| − | Foster, A, and Foll, C. (2003) '''BSAVA small animal dermatology '''(second edition) ''British Small Animal Veterinary Association''
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| − | Fox, M and Jacobs, D. (2007) '''Parasitology Study Guide Part 1: Ectoparasites''''' Royal Veterinary College''
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| − | {{review}}
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| − | ==Webinars==
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| − | <rss max="10" highlight="none">https://www.thewebinarvet.com/parasitology/webinars/feed</rss>
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| − | [[Category:Expert_Review]] | |
| − | [[Category:Integumentary_System_-_Mite_Infections]] [[Category:Zoonoses]]
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| − | [[Category:Dermatological Diseases - Cat]][[Category:Dermatological Diseases - Dog]][[Category:Dermatological Diseases - Horse]][[Category:Dermatological Diseases - Cattle]][[Category:Dermatological Diseases - Sheep]][[Category:Dermatological Diseases - Goat]] | |