Difference between revisions of "Myiasis Producing Flies"

From WikiVet English
Jump to navigation Jump to search
(Redirected page to Category:Myiasis Producing Flies)
 
(58 intermediate revisions by 6 users not shown)
Line 1: Line 1:
{{unfinished}}
 
  
{{toplink
 
|backcolour =
 
|linkpage =Insecta
 
|linktext =INSECTA
 
|pagetype=Bugs
 
|sublink1=Parasites
 
|subtext1=PARASITES
 
}}
 
<br>
 
  
==Introduction==
 
  
Myiasis is the parasitism of living animals by dipteran larvae. Myiasis can be oligatory or facultative (optional) and is described as cutaneous, nasal or somatic.
 
  
==Oestridae==
+
#REDIRECT[[:Category:Myiasis Producing Flies]]
 
 
*The larvae of Oestridae spp. are '''obligatory''' parasites
 
 
 
*The three important species of veterinary interest are ''Hypoderma'', ''Oestrus'' and ''Gasterophilus''
 
 
 
===''Hypoderma'' spp.===
 
 
 
*Also known as warble flies
 
 
 
*Important cattle parasites
 
**Also parasitise horses, small ruminants and sometimes humans
 
 
 
*The two main species in cattle are ''H. bovis'' and ''H. lineatum''
 
 
 
*''H. diana'' parasitises deer
 
 
 
*Infestation is largely confined to the Northern Hemisphere
 
 
 
'''Recognition'''
 
*Large 13-15mm long
 
 
 
*Similar to bumble bees in appearance
 
**Yellow abdomen
 
*Band of black hairs
 
 
 
*One pair of wings
 
 
 
'''Life Cycle'''
 
*Adult flies emerge on warm, sunny days between June and August
 
 
 
*White eggs are laid around the belly and legs of the animal
 
**Eggs are attached to hairs by cement and a small terminal clasp
 
**''H. lineatum'' lays a whole row of eggs as it approaches the animal stealthily
 
**''H. bovis'' only deposits a single egg before the animal runs away (''''gadding''') as it makes a loud buzzing noise
 
 
 
*The adult lives for 3 weeks
 
 
 
*Females can lay several hundred eggs in their life
 
 
 
*A few days after eggs are laid, larvae emerge and crawl down the hairs into the hair follicles
 
 
 
*Larvae penetrate the skin through wounds made by [[Biting Flies - WikiBlood|biting flies]]
 
 
 
*Larvae migrate through the subcutaneous tissue towards the diaphragm
 
**Enzymatic secretions and mouth hooks aids larval migration
 
 
 
*After 3 months larvae reach '''winter resting sites''' where they remain from November to Feburary/March whilst moulting to the L2 stage
 
**Epidural fat in the spinal canal for ''H. bovis''
 
**Wall of the oesophagus for ''H. lineatum''
 
 
 
*Larvae then migrate back to the subcutis along the midline of the back where they bore a breathing hole through the skin and moult to the L3 stage
 
**Larvae are palpable as distinct swellings called '''warbles'''
 
 
 
*L3 larvae emerge after 4-10 weeks where they fall to the ground and pupate under loose vegetation
 
 
 
*Adult flies emerge from the pupa after one month where they copulate, lay eggs and die within two weeks
 
 
 
*''H. lineatum'' are on the wing 6-8 weeks before ''H. bovis''
 
 
 
*There is only '''one''' generation of warble flies per year
 
 
 
'''Pathogenesis'''
 
*Causes[[Muscles Inflammatory - Pathology#Arthropods| myositis]]
 
 
 
*Production losses
 
**Condemnation and down-grading of hides
 
**Reduced milk yield and reduced weight gain
 
**Injury from stock panic
 
**Trimmed meat losses from ''H. lineatum''
 
***'Butcher's Jelly' around warbles which is green due to mass [[Eosinophils - WikiBlood|eosinophil]] attraction
 
 
 
*Paraplegia resulting from:
 
**Toxin release
 
**Pressure on the spinal cord (''H. bovis'')
 
**Bloat from pressue on the oesophageal wall (''H. lineatum'')
 
 
 
'''Control'''
 
*Total eradication should be aimed for
 
 
 
*Old methods include popping out warbles
 
**But could lead to anaphylactic shock
 
 
 
*[[Ectoparasiticides]]
 
**Systemic organophosphorus [[Ectoparasiticides|insecticides]] in pour-on formula
 
**Avermectins and milbemycins in pour-on and injectible formulations
 
 
 
*Timing is crucial for treatment
 
**Larvae residing in winter resting sites, if killed, can lead to bloat and paraplegia
 
**It is safe to treat in the '''autumn''' before larvae reach their winter resting sites and in the '''spring''' when the warbles have migrated to the midline of the back
 
**Ivermectin can be given at any time without risking host infection as larval antigen is released much slower
 
 
 
'''Legislation in the UK'''
 
*'Warble Fly Order 1978' requires all clinically affected animals to be treated
 
 
 
*Notifiable disease
 
 
 
*'Warble Fly Infected Area Order 1983'
 
 
 
*For more information on the warble fly orders, see[http://www.defra.gov.uk/animalh/diseases/notifiable/brucellosis/surveillance.htm|here]
 
 
 
 
 
===''Oestrus ovis''===
 
 
 
*Also known as the sheep nasal bot fly
 
 
 
'''Recognition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
*[[Respiratory Parasitic Infections - Pathology#Oestrus ovis|Apthology in the nasal cavity]]
 
 
 
'''Control'''
 
 
 
===''Gasterophilus'' spp.===
 
 
 
*Also known as the horse bot fly
 
 
 
'''Recognition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
 
 
'''Control'''
 
 
 
===''Dermatobia hominis''===
 
 
 
'''Recongition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
 
 
'''Control'''
 
 
 
==Calliphoridae==
 
 
 
'''Recongition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
 
 
'''Control'''
 
 
 
==Screw Worm Myiasis==
 
 
 
'''Recongition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
 
 
'''Control'''
 
 
 
==''Wohlfahrtia'' sp.==
 
 
 
'''Recongition'''
 
 
 
'''Life Cycle'''
 
 
 
'''Pathogenesis'''
 
 
 
'''Control'''
 
 
 
==Links==
 
 
 
*[[Viruses]]
 
 
 
*[[Ectoparasiticides]]
 

Latest revision as of 13:14, 5 April 2010