Difference between revisions of "Stephanofilaria stilesi"
Jump to navigation
Jump to search
| (20 intermediate revisions by 4 users not shown) | |||
| Line 1: | Line 1: | ||
| − | + | <big><center>[[Filarioidea|'''BACK TO FILARIOIDEA''']]</center></big> | |
| − | |||
| − | | | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
| − | == | + | ==Stephanofilaira stilesi== |
| + | *Dermall lesions of cattle in USA | ||
| − | + | ===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=== |
| − | These | + | *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=== | ||
| + | # Pelodera strongyloides: | ||
| + | #*Rhabditid parasite, adults 1-1.5mm long, found in follicles | ||
| + | #*uteri contain eggs, not microfilaria. | ||
| + | # Dermatophytosis (Trichophyton verrucosum is most common) | ||
| + | # Mange (Chorioptes bovis) | ||
| + | # Fly bite dermatitis | ||
| + | # Contact dermatitis | ||
| + | # Zn-responsive dermatitis | ||
| + | # 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 | |
| + | * | ||
Revision as of 15:35, 29 November 2007
Stephanofilaira stilesi
- Dermall lesions of cattle in USA
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
- Pelodera strongyloides:
- Rhabditid parasite, adults 1-1.5mm long, found in follicles
- uteri contain eggs, not microfilaria.
- Dermatophytosis (Trichophyton verrucosum is most common)
- Mange (Chorioptes bovis)
- Fly bite dermatitis
- Contact dermatitis
- Zn-responsive dermatitis
- 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