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New page: {{unfinished}} {{toplink |linkpage =Viruses |linktext =VIRUSES |sublink1=Poxviridae |subtext1=POXVIRUSES |pagetype =Bugs }} <br> Also known as '''Contagious Pustular Dermatitis''', '''Co...
{{unfinished}}
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Poxviridae
|subtext1=POXVIRUSES
|pagetype =Bugs
}}
<br>
Also known as '''Contagious Pustular Dermatitis''', '''Contagious Ecthyma''' and '''Scabby Mouth''', Orf is the most common viral '''zoonosis''' in the UK.
====Morphology====
*The virus is a large, enveloped, highly epitheliotropic, DNA virus which is ovoid in shape and measures 220‑300 x 140‑170 nm
*There are over 100 polypeptides in the virion
*The core proteins include a transcriptase and several other enzymes
*The virus is immunologically related to those causing bovine papular stomatitis, pseudocowpox, sealpox, deer PPV, red squirrel PPV and camel PPV
*There is extensive cross‑neutralization and cross‑protection between viruses belonging to the same genus, but not between those of different genera
*The virus is resistant to desiccation
====Hosts====
*Acute debilitating but rarely fatal skin disease of sheep, goats and incidentally of ruminants and humans
====Pathogenesis====
*Trauma, then lesions on skin without wool
*Lesions on udder and throat
*Lesions coalesce to form scabbed masses
*Particular concern for '''lambs''', who stop feeding due to mouth lesions
*For more, see [[Viral skin infections - Pathology#Contagious ecthyma|here]]
*In man, papules and pustules develop on hands within 10 days, enlarge and then regress after several weeks
====Epidemiology====
*Morbidity may reach 90%, but mortality rarely exceeds 1%, unless secondary infection or myiasis occurs
*The course of the disease without complications is 2‑6 weeks, and it takes about 10 weeks to run a course through a naive flock, but often lingers indefinitely in the flock because it can reinfect the same animal many times and is resistant to desiccation
====Differentials====
*Sheep pox: A more severe disease
**Characterized by elevated papules distributed diffusely over the skin surface
**Inclusion bodies are often seen, but there is no down‑growth of epidermis
**High mortality
*Ulcerative dermatosis:
**Characterized by ulcers and crusts on the skin of the face, feet and genitalia
**The lesions are not elevated because there is no epithelial hyperplasia
*[[Bluetongue Virus]]:
**There is a lower morbidity but a high mortality
**The disease is usually seen in adult animals
**This is a severe systemic disease which is a differential only for the rare, systemic form of CE
*Mycotic dermatitis:
**The scabs are smaller and thinner and lighter and usually yellowish in color, with crusts not firmly attached
*Foot and mouth disease: When lesions occur in the mouth
====Control====
*Attenuated virus can be applied by scarification to axillar, causing scabs to fall off in 30 days
*Annual '''vaccination''' of ewes at least 8 weeks before lambing (all in contact should be done simultaneously)
*In an outbreak, all lambs can be vaccinated
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Poxviridae
|subtext1=POXVIRUSES
|pagetype =Bugs
}}
<br>
Also known as '''Contagious Pustular Dermatitis''', '''Contagious Ecthyma''' and '''Scabby Mouth''', Orf is the most common viral '''zoonosis''' in the UK.
====Morphology====
*The virus is a large, enveloped, highly epitheliotropic, DNA virus which is ovoid in shape and measures 220‑300 x 140‑170 nm
*There are over 100 polypeptides in the virion
*The core proteins include a transcriptase and several other enzymes
*The virus is immunologically related to those causing bovine papular stomatitis, pseudocowpox, sealpox, deer PPV, red squirrel PPV and camel PPV
*There is extensive cross‑neutralization and cross‑protection between viruses belonging to the same genus, but not between those of different genera
*The virus is resistant to desiccation
====Hosts====
*Acute debilitating but rarely fatal skin disease of sheep, goats and incidentally of ruminants and humans
====Pathogenesis====
*Trauma, then lesions on skin without wool
*Lesions on udder and throat
*Lesions coalesce to form scabbed masses
*Particular concern for '''lambs''', who stop feeding due to mouth lesions
*For more, see [[Viral skin infections - Pathology#Contagious ecthyma|here]]
*In man, papules and pustules develop on hands within 10 days, enlarge and then regress after several weeks
====Epidemiology====
*Morbidity may reach 90%, but mortality rarely exceeds 1%, unless secondary infection or myiasis occurs
*The course of the disease without complications is 2‑6 weeks, and it takes about 10 weeks to run a course through a naive flock, but often lingers indefinitely in the flock because it can reinfect the same animal many times and is resistant to desiccation
====Differentials====
*Sheep pox: A more severe disease
**Characterized by elevated papules distributed diffusely over the skin surface
**Inclusion bodies are often seen, but there is no down‑growth of epidermis
**High mortality
*Ulcerative dermatosis:
**Characterized by ulcers and crusts on the skin of the face, feet and genitalia
**The lesions are not elevated because there is no epithelial hyperplasia
*[[Bluetongue Virus]]:
**There is a lower morbidity but a high mortality
**The disease is usually seen in adult animals
**This is a severe systemic disease which is a differential only for the rare, systemic form of CE
*Mycotic dermatitis:
**The scabs are smaller and thinner and lighter and usually yellowish in color, with crusts not firmly attached
*Foot and mouth disease: When lesions occur in the mouth
====Control====
*Attenuated virus can be applied by scarification to axillar, causing scabs to fall off in 30 days
*Annual '''vaccination''' of ewes at least 8 weeks before lambing (all in contact should be done simultaneously)
*In an outbreak, all lambs can be vaccinated