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| + | #REDIRECT[[:Category:Crustacea]] |
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| − | {{toplink
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| − | |backcolour =
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| − | |linkpage =Parasites
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| − | |linktext =PARASITES
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| − | |pagetype=Bugs
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| − | }}
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| − | <br>
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| − | ==Introduction==
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| − | The crustacea are a large group of arthropods but are usually treated as a subphylum. The majority of crustaceans are aquatic but some have adapted to terrestrial life.
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| − | There are only two species of parasitic crustacea of veterinary importance, the tongue worm ''Linguatula serrata'' and sealice ''Lepeophtheirus and Caligus'' spp.
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| − | ==''Linguatula serrata''==
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| − | [[Image:Linguatula taenioides.jpg|right|thumb|150px|Copyright Cooper Curtice (Washington, Government Printing Office, 1890) Wikimedia Commons]]
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| − | *Also known as the 'tongue worm'
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| − | *Are highly specialised [[Arthropods|arthropods]]
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| − | '''Recognition'''
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| − | *Tongue-like appearance
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| − | **Expanded anteriorly
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| − | *Adults are over 10cm in length
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| − | **Females measure betwen 30-130mm in length
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| − | **Males measure up to 20mm in length
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| − | *Transversely striated
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| − | '''Life Cycle'''
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| − | *6 month life cycle
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| − | *Adults inhabit the nasal passages of dogs and sometimes cats
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| − | *Eggs are expelled by coughing and sneezing or are passed out with the faeces
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| − | *Herbivorous intermediate hosts ingest the eggs
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| − | *Eggs hatch in the herbivore intestine
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| − | *Larvae migrate to the mesenteric lymph nodes and encyst to become infective nymphs
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| − | **Cysts measure 1mm in diameter
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| − | *When a dog eats infeced uncooked viscera the life cycle is completed
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| − | *Infective nymphs migrate from the viscera during chewing and crawl up into the nasal cavity via the soft palate
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| − | *Infective nymphs mature to adults in the nasal cavities and can survive for a year in the final host
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| − | '''Pathogenesis'''
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| − | *Causes [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
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| − | *Heavy infection leads to coughing, sneezing and nasal discharge
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| − | ==Sea Lice==
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| − | [[Image:Sea Lice.jpg|right|thumb|200px|Sea Lice - Copyright Joseph G. Kunkel at The Kunkel Fish & Aquatic Invert Site]] | |
| − | *Economic imortance to the fish farming industries
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| − | **Especially in North American and in Northern Europe
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| − | *''Lepeophtheirus'' is found only the Northern hemisphere
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| − | *''Caligus'' is found worldwide
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| − | '''Recognition'''
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| − | *Males measure 6mm in length
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| − | *Females measure 1cm long
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| − | **Have a long egg sac
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| − | *5 pairs of legs
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| − | **3 pairs for swimming
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| − | **2 pairs modified for eating
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| − | *Brown to red in colour
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| − | *Similar in appearance to the horse shoe crab
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| − | '''Life Cycle'''
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| − | *Eggs released from long egg sacs into environment
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| − | *2 non-parasitic larval stages
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| − | *7 parasitic larval stages (nauplius)
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| − | **Copepod, chalimus and pre-adult
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| − | *Life cycle takes 3 weeks to 4 months depending on temperature
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| − | '''Epidemiology'''
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| − | *Largely found in salt water
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| − | *Most wild salmonids migrate to the sea for part of their life cycle
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| − | *Sealice numbers are low on wild salmonids (adults only)
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| − | *Sealice numbers are high on farmed salmonids (larvae and adults)
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| − | **90% prevalence
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| − | **Average of 5-10 sealice upon a single fish
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| − | **Most sealice found on dorsal fin, head and back and underside of tail and fins
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| − | **Adults survive for over 3 weeks
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| − | **Migration of larval stages can be up to 1km
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| − | **Larvae locate host by responding to changes in light and vibration
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| − | '''Pathogenesis'''
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| − | *Adults and larval stages are epidermal browsers
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| − | *Mouth tube of toothed ridges abrades fish epidermis
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| − | *Heavy infections leads to:
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| − | **Epidermal abrasion
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| − | **Haemorrhage
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| − | **Immunosuppression
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| − | **Decreased productivity
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| − | **Death
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| − | '''Control'''
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| − | *Ectoparasites
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| − | *Hidden antigen vaccine
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| − | *Wrasse which feed on sealice
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| − | *Managment improvements
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| − | **E.g. ''All in, all out'' and 6 week fallowing
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| − | *Stock selection
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| − | **e.g. Selective breeding for resistance
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| − | ==Links==
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| − | [[Respiratory Parasitic Infections - Pathology#Linguatula serrata|Pathology of ''Linguata serrata'' in the nasal passages]]
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