Difference between revisions of "Stephanofilaria stilesi"

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{{Taxobox
 
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|name              =''Stephanofilaira stilesi
 
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|kingdom            =
 
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|phylum            =
 
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|class              = [[Nematodes|Nematoda]]
 
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|sub-class          =
 
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|order              =
 
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|super-family      = [[Filarioidea]]
 
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|family            =
 
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|sub-family        =
 
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|genus              =
 
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|species            =
 
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}}
 
  
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==Hosts==
 
  
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'''Intermediate hosts''':  The horn fly, ''[[Haematobia irritans]]''
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==Stephanofilaira stilesi==
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*[[Stephanofilariasis|Dermall lesions]] of cattle in USA
  
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'''Definitive hosts''': Cattle
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===Lifecycle===
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*The infective larvae develop in the horn fly - Haematobia irritans
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**Flies ingest microfilaria as they feed on cutaneous lesions.  
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**Microfilaria develop into L3 larvae in the hornfly over 18-21 days. 
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**Infective L3 larva are deposited into the skin when the fly bites again, where they grow into adult worms.
  
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==Identification==
 
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These small [[Nematodes|nematodes]] are between 3-6mm in length. The eggs have thin shells, and are around 65μm in length. The microfilaria are 50μm long and enclosed in a spherical, vitelline membrane.
 
  
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==Lifecycle==
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===Gross pathology===
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Horn flies feed on lesions found on the host skin, and ingest microfilariae, as they feed on cutaneous lesions. They later develop into L3 in around 18-21 days.  The definitive host is infected when the fly leaves the L3 on the host.
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*Lesions begin as small circular patches on the ventral midline with serous exudate. 
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*These enlarge and coalesce producing lesions 25cm or more in diameter.   
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*Hemorrhage develops along the periphery while the older, central areas develop scabs or dry crusts. 
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*Healing lesions are alopecic, lichenified plaques.
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*Lesions may also occur on the flank, udder, teats, face and neck.
  
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Causes [[Stephanofilariasis]].
 
  
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{{Learning
 
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|literature search = [http://www.cabdirect.org/search.html?q=title:(%22Stephanofilaria+stilesi%22) ''Stephanofilaria stilesi'' publications]
 
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===Histopathology===
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*Adult parasites occur within cystic diverticula of hair follicles or free within the adjacent dermis. 
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**Parasites may have lateral cords and lateral cuticular projections. 
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**The thick intestine is distinctive.
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**Microfilariae within uteri is the key feature. 
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***Microfilariae also occur free within the dermis, in dermal lymphatics, or in the surface exudate. 
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*There is little dermal reaction to adults in cystic hair follicles, but their presence within the dermis elicits eosinophilic and mononuclear inflammation.
  
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===Differential diagnosis===
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# Pelodera strongyloides: 
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#*Rhabditid parasite, adults 1-1.5mm long, found in follicles
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#*uteri contain eggs, not microfilaria.
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# Dermatophytosis (Trichophyton verrucosum is most common)
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# Mange (Chorioptes bovis)
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# Fly bite dermatitis
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# Contact dermatitis
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# Zn-responsive dermatitis
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# Other subcutaneous filarid parasites: 
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#*Parafilaria bovicola (adult worms 30-70mm long, found coiled in nodules in subcutaneous and intramuscular connective tissues; not seen in US)
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#*Onchocerca gutterosa (adult worms 60mm long, found in nuchal ligament and subcutaneous connective tissues).
  
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==Stephanofilaria assamensis==
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*'Humpsore'
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*''Bos indicus'' in India
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*
 
[[Category:Filarioidea]]
 
[[Category:Filarioidea]]
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[[Category:To_Do_-_Max]]

Revision as of 16:38, 29 July 2010


 This article is still under construction.



Stephanofilaira stilesi

Lifecycle

  • The infective larvae develop in the horn fly - Haematobia irritans
    • Flies ingest microfilaria as they feed on cutaneous lesions.
    • Microfilaria develop into L3 larvae in the hornfly over 18-21 days.
    • Infective L3 larva are deposited into the skin when the fly bites again, where they grow into adult worms.


Gross pathology

  • Lesions begin as small circular patches on the ventral midline with serous exudate.
  • These enlarge and coalesce producing lesions 25cm or more in diameter.
  • Hemorrhage develops along the periphery while the older, central areas develop scabs or dry crusts.
  • Healing lesions are alopecic, lichenified plaques.
  • Lesions may also occur on the flank, udder, teats, face and neck.


Histopathology

  • Adult parasites occur within cystic diverticula of hair follicles or free within the adjacent dermis.
    • Parasites may have lateral cords and lateral cuticular projections.
    • The thick intestine is distinctive.
    • Microfilariae within uteri is the key feature.
      • Microfilariae also occur free within the dermis, in dermal lymphatics, or in the surface exudate.
  • There is little dermal reaction to adults in cystic hair follicles, but their presence within the dermis elicits eosinophilic and mononuclear inflammation.

Differential diagnosis

  1. Pelodera strongyloides:
    • Rhabditid parasite, adults 1-1.5mm long, found in follicles
    • uteri contain eggs, not microfilaria.
  2. Dermatophytosis (Trichophyton verrucosum is most common)
  3. Mange (Chorioptes bovis)
  4. Fly bite dermatitis
  5. Contact dermatitis
  6. Zn-responsive dermatitis
  7. Other subcutaneous filarid parasites:
    • Parafilaria bovicola (adult worms 30-70mm long, found coiled in nodules in subcutaneous and intramuscular connective tissues; not seen in US)
    • Onchocerca gutterosa (adult worms 60mm long, found in nuchal ligament and subcutaneous connective tissues).

Stephanofilaria assamensis

  • 'Humpsore'
  • Bos indicus in India
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