Changes

Jump to navigation Jump to search
3,118 bytes removed ,  14:39, 2 August 2007
Line 2: Line 2:  
==Aphthoviruses==
 
==Aphthoviruses==
 
===Foot and Mouth Disease Virus===
 
===Foot and Mouth Disease Virus===
====Introduction====
  −
*Affects all cloven hoofed animals, cattle, sheep and pigs and others.
  −
*1967 + 2001  major outbreaks in UK.
  −
*Controlled by slaughter policy in UK.
  −
*Still widespread in many parts of world especially S. America, far East.
  −
*Very infectious virus.
  −
====Clinical====
  −
*Foot and Mouth disease is not a high fatal disease - approximately 5% mortality, usually young animals, older animals recover but stop giving milk yield - i.e. production losses are important factor.
  −
*It is very debilitating and animals take weeks or months to recover.
  −
*Economic impact as stops export of cattle and cattle products.
  −
*Fairly easy to diagnose in classical form - difficult in sheep.
  −
*Animals froth at mouth, usually in more than one animal (one animal may be just sore mouth from another cause).
  −
*Lameness in a number of animals.
  −
*Characteristic lesions in mouth that are short lived.
  −
*Incubation from two days up to 3 weeks in sheep.
  −
====Pathology====
  −
=====Gross=====
  −
#Initially - hyperaemia of mucosa (e.g. catarrhal inflammation) then within 12 hours produces fluid filled vesicles on dorsum of tongue, may be other places.
  −
#Small vesicle coalesce to produce big ones -i.e. Bullae.
  −
#Very quickly rupture; epithelium appears dirty grey in colour because of necrosis - sloughed skin, very good for diagnosis.
  −
#Leave painful, hyperaemic epithelium.
  −
#Looks like "ulcer "with ragged edge but not a true ulcer as stratum germinativum retained and will rapidly heal completely in about 2 weeks unless becomes secondarily infected.
  −
  −
*Also produces sores in interdigital cleft, at coronet and bulbs of heals.
  −
**These feet lesions often take a long time to heal as secondary infections may ensue and produce true deep ulceration.
  −
*Teats on animals that are suckling may also develop vesicles.
  −
  −
*Sheep develop very few vesicles in mouth but foot lesions can be dramatic - like a whole flock with foot rot.  N.B. Can also be very mild!
  −
*Coronets are very red with vesicles and sores.
  −
  −
*Pigs have vesicles on snout, which are quickly eroded - hard to look at pig’s tongue. 
  −
*Hoof lesions like other species; hoof may come off, known as "thimbling".
  −
*Lesions will heal eventually but is very painful (Often need euthanasia)
  −
  −
=====Microscopic lesions=====
  −
*Degeneration of prickle cells. 
  −
*Cells "balloon" as fill with fluid and then die to produce vesicle containing straw coloured or clear fluid.
  −
  −
====Diagnosis====
  −
Definitive diagnosis.
  −
  −
N.B.  Notifiable Disease.
  −
  −
*Inform MAFF (and police) as soon as suspect clinical diagnosis.
  −
*MAFF will take specimens of fluid from vesicle. Suck out fluid with syringe.
  −
*Skin that has sloughed off vesicle also good for diagnosis.
  −
*If the above two are not available can use scraping of base of erosion.
  −
  −
*May see animals that have discoloration of tongue due to having had FMD.  In these cases take scraping of retropharyngeal region, put scrapings in transport medium.
  −
  −
#Atigen capture ELISA
  −
#PCR
  −
#Culture (need ph7 buffered transport media)
  −
#Antibody capture ELISA
  −
  −
*In foot and mouth disease usually use ELISA to provide quick diagnosis - especially if have vesicular fluid.
      
==Enteroviruses==
 
==Enteroviruses==
965

edits

Navigation menu