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Stephanofilaria stilesi (view source)

Revision as of 10:00, 30 July 2010

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{{Taxobox
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|name              =''Stephanofilaria spp.
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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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==Stephanofilaira stilesi==
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=Stephanofilaira stilesi=
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*[[Stephanofilariasis|Dermall lesions]] of cattle in USA
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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          =
 +
|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 e.g [[Haematobia irritans]]
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'''Definitive hosts''':  Cattle.
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==Identification==
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These small nematodes are between 3-6mm in lenth. 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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Horn flies feed on lesions found on the host skin, and ingest microfilariae, which later develop into L3.  The definitive host is infected when the fly leaves the L3 on the host.
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===Lifecycle===
   
*The infective larvae develop in the horn fly - Haematobia irritans
 
*The infective larvae develop in the horn fly - Haematobia irritans
 
**Flies ingest microfilaria as they feed on cutaneous lesions.   
 
**Flies ingest microfilaria as they feed on cutaneous lesions.   
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===Gross pathology===
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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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===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]]
 
[[Category:To_Do_-_Max]]
 
[[Category:To_Do_-_Max]]
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