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| − | ==Stephanofilaira stilesi== | + | {{OpenPagesTop}} |
| − | *Dermall lesions of cattle in USA
| + | {{Taxobox |
| | + | |name =''Stephanofilaira stilesi |
| | + | |kingdom = |
| | + | |phylum = |
| | + | |class = [[Nematodes|Nematoda]] |
| | + | |sub-class = |
| | + | |order = |
| | + | |super-family = [[Filarioidea]] |
| | + | |family = |
| | + | |sub-family = |
| | + | |genus = |
| | + | |species = |
| | + | }} |
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| − | ===Lifecycle=== | + | ==Hosts== |
| − | *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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| | + | '''Intermediate hosts''': The horn fly, ''[[Haematobia irritans]]'' |
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| − | ===Gross pathology===
| + | '''Definitive hosts''': Cattle |
| − | *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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| | + | ==Identification== |
| | + | 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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| − | ===Histopathology=== | + | ==Lifecycle== |
| − | *Adult parasites occur within cystic diverticula of hair follicles or free within the adjacent dermis.
| + | 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. |
| − | **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===
| + | Causes [[Stephanofilariasis]]. |
| − | # Pelodera strongyloides: Rhabditid parasite, adults 1-1.5mm long, found in follicles; 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== | + | {{Learning |
| − | *'Humpsore'
| + | |literature search = [http://www.cabdirect.org/search.html?q=title:(%22Stephanofilaria+stilesi%22) ''Stephanofilaria stilesi'' publications] |
| − | *''Bos indicus'' in India
| + | }} |
| − | *
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| | + | {{OpenPages}} |
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| | + | [[Category:Filarioidea]] |