|
|
| (8 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| − | | + | #REDIRECT[[:Category:Crustacea]] |
| − | {{toplink
| |
| − | |backcolour =
| |
| − | |linkpage =Parasites
| |
| − | |linktext =PARASITES
| |
| − | |pagetype=Bugs
| |
| − | }}
| |
| − | <br>
| |
| − | | |
| − | ==Introduction==
| |
| − | | |
| − | 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.
| |
| − | | |
| − | There are only two species of parasitic crustacea of veterinary importance, the tongue worm ''Linguatula serrata'' and sealice ''Lepeophtheirus and Caligus'' spp.
| |
| − | | |
| − | ==''Linguatula serrata''==
| |
| − | [[Image:Linguatula taenioides.jpg|right|thumb|150px|Copyright Cooper Curtice (Washington, Government Printing Office, 1890) Wikimedia Commons]]
| |
| − | *Also known as the 'tongue worm'
| |
| − | | |
| − | *Are highly specialised [[Arthropods|arthropods]]
| |
| − | | |
| − | '''Recognition'''
| |
| − | *Tongue-like appearance
| |
| − | **Expanded anteriorly
| |
| − | | |
| − | *Adults are over 10cm in length
| |
| − | **Females measure betwen 30-130mm in length
| |
| − | **Males measure up to 20mm in length
| |
| − | | |
| − | *Transversely striated
| |
| − | | |
| − | '''Life Cycle'''
| |
| − | *6 month life cycle
| |
| − | | |
| − | *Adults inhabit the nasal passages of dogs and sometimes cats
| |
| − | | |
| − | *Eggs are expelled by coughing and sneezing or are passed out with the faeces
| |
| − | | |
| − | *Herbivorous intermediate hosts ingest the eggs
| |
| − | | |
| − | *Eggs hatch in the herbivore intestine
| |
| − | | |
| − | *Larvae migrate to the mesenteric lymph nodes and encyst to become infective nymphs
| |
| − | **Cysts measure 1mm in diameter
| |
| − | | |
| − | *When a dog eats infeced uncooked viscera the life cycle is completed
| |
| − | | |
| − | *Infective nymphs migrate from the viscera during chewing and crawl up into the nasal cavity via the soft palate
| |
| − | | |
| − | *Infective nymphs mature to adults in the nasal cavities and can survive for a year in the final host
| |
| − | | |
| − | '''Pathogenesis'''
| |
| − | *Causes [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
| |
| − | | |
| − | *Heavy infection leads to coughing, sneezing and nasal discharge
| |
| − | | |
| − | ==Sea Lice==
| |
| − | [[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
| |
| − | **Especially in North American and in Northern Europe
| |
| − | | |
| − | *''Lepeophtheirus'' is found only the Northern hemisphere
| |
| − | | |
| − | *''Caligus'' is found worldwide
| |
| − | | |
| − | '''Recognition'''
| |
| − | | |
| − | *Males measure 6mm in length
| |
| − | | |
| − | *Females measure 1cm long
| |
| − | **Have a long egg sac
| |
| − | | |
| − | *5 pairs of legs
| |
| − | **3 pairs for swimming
| |
| − | **2 pairs modified for eating
| |
| − | | |
| − | *Brown to red in colour
| |
| − | | |
| − | *Similar in appearance to the horse shoe crab
| |
| − | | |
| − | '''Life Cycle'''
| |
| − | *Eggs released from long egg sacs into environment
| |
| − | | |
| − | *2 non-parasitic larval stages
| |
| − | | |
| − | *7 parasitic larval stages (nauplius)
| |
| − | **Copepod, chalimus and pre-adult
| |
| − | | |
| − | *Life cycle takes 3 weeks to 4 months depending on temperature
| |
| − | | |
| − | '''Epidemiology'''
| |
| − | *Largely found in salt water
| |
| − | | |
| − | *Most wild salmonids migrate to the sea for part of their life cycle
| |
| − | | |
| − | *Sealice numbers are low on wild salmonids (adults only)
| |
| − | | |
| − | *Sealice numbers are high on farmed salmonids (larvae and adults)
| |
| − | **90% prevalence
| |
| − | **Average of 5-10 sealice upon a single fish
| |
| − | **Most sealice found on dorsal fin, head and back and underside of tail and fins
| |
| − | **Adults survive for over 3 weeks
| |
| − | **Migration of larval stages can be up to 1km
| |
| − | **Larvae locate host by responding to changes in light and vibration
| |
| − | | |
| − | '''Pathogenesis'''
| |
| − | *Adults and larval stages are epidermal browsers
| |
| − | | |
| − | *Mouth tube of toothed ridges abrades fish epidermis
| |
| − | | |
| − | *Heavy infections leads to:
| |
| − | **Epidermal abrasion
| |
| − | **Haemorrhage
| |
| − | **Immunosuppression
| |
| − | **Decreased productivity
| |
| − | **Death
| |
| − | | |
| − | '''Control'''
| |
| − | *Ectoparasites
| |
| − | | |
| − | *Hidden antigen vaccine
| |
| − | | |
| − | *Wrasse which feed on sealice
| |
| − | | |
| − | *Managment improvements
| |
| − | **E.g. ''All in, all out'' and 6 week fallowing
| |
| − | | |
| − | *Stock selection
| |
| − | **e.g. Selective breeding for resistance
| |
| − | | |
| − | ==Links==
| |
| − | | |
| − | [[Respiratory Parasitic Infections - Pathology#Linguatula serrata|Pathology of ''Linguata serrata'' in the nasal passages]]
| |