Difference between revisions of "Orf"

Revision as of 17:45, 30 October 2008

Also known as Contagious Pustular Dermatitis, Contagious Ecthyma and Scabby Mouth, Orf is the most common viral zoonosis in the UK.

Contagious ecthyma (Courtesy of Bristol BioMed Image Archive)

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 and in mouth
Lesions coalesce to form scabbed masses
Particular concern for lambs, who stop feeding due to mouth lesions
For more, see 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

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+{{unfinished}}
-Also know as: '''''Contagious Pustular Dermatitis — CPD — Contagious Ecthyma — Scabby Mouth'''''
-== Introduction ==
+{{toplink
-[[Image: Contagious ecthyma.jpg|200px|thumb|right|<small><center>Contagious ecthyma (Courtesy of Bristol BioMed Image Archive)</center></small>]]
+|linkpage =Viruses
-Orf is the most common viral '''zoonosis''' in the UK. It causes an acute debilitating but rarely fatal skin disease of sheep, goats and incidentally of ruminants and humans. It is a Parapox virus of the family [[Poxviridae]] and infects by entering a skin lesion in places such as the udder, mouth and throat. These lesions then coalesce to form scabbed masses. It is of particular concern in lambs as mouth lesions prevent them from suckling due to pain. If the sheep has lesions on her udder she is also unlikely to want to let her lambs suckle.
+|linktext =VIRUSES
+|sublink1=Poxviridae
-The virus is a large, enveloped, highly epitheliotropic, DNA virus which is ovoid in shape and measures 220‑300 x 140‑170 nm and 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|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.
+|subtext1=POXVIRUSES
+|pagetype =Bugs
-Morbidity in a flock may reach 90% but mortality is incredibly rare, reaching 1% maximum, unless secondary myiasis (blowfly strike) 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.
-== Clinical Signs ==
-Failure to gain weight in lambs, plus the presence of scabby lesions on the mouth. Similar lesions on the mouth and udder of ewes and a reluctance to eat in these animals. In man, papules and pustules develop on hands within 10 days, enlarge and then regress after several weeks.
-== Diagnosis ==
-The virus can be identified by direct electron microscopy of samples from fresh lesions.
-Differential diagnoses include [[Sheep Pox]], which is a more severe disease characterized by elevated papules distributed diffusely over the skin surface and high mortality rates are seen. Ulcerative dermatosis is another differential and is also characterized by ulcers and crusts on the skin of the face, feet and genitalia, however the lesions are not elevated because there is no epithelial hyperplasia. [[Bluetongue Virus]] is another differential. There is lower morbidity but a high mortality and the disease is usually seen in adult animals. Mycotic dermatitis is a differential although the scabs are smaller and thinner and lighter and usually yellowish in color, with crusts not firmly attached. [[Foot and Mouth Disease|Foot and mouth disease]] can be a differential when lesions occur in the mouth.
-== Control ==
-Attenuated virus can be applied by scarification to axillar or tail base, 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) is required. In an outbreak, all lambs can be vaccinated .
-{{Learning
-|Vetstream = [https://www.vetstream.com/canis/search?s=Orf Orf]
-|flashcards = [[Sheep Medicine Q&A 05]]
 }}
+<br>
-== References ==
+Also known as '''Contagious Pustular Dermatitis''', '''Contagious Ecthyma''' and '''Scabby Mouth''', Orf is the most common viral '''zoonosis''' in the UK.
+[[Image: Contagious ecthyma.jpg|200px|thumb|right|<small><center>Contagious ecthyma (Courtesy of Bristol BioMed Image Archive)</center></small>]]
-Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary''' (2nd Edition) ''Elsevier Science''
-Bridger, J and Russell, P (2007) '''Virology Study Guide''', ''Royal Veterinary College''
+====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
-Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) '''Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats and horses''' ''Elsevier Health Sciences''
+====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 and in [[Cavity & Gingiva - Pathology#Orf|mouth]]
+*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
-{{review}}
+====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
-{{OpenPages}}
+====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
-[[Category:Poxviridae]] [[Category:Sheep_Viruses]] [[Category:Goat_Viruses]] [[Category:Zoonoses]] [[Category:Oral_Cavity_-_Proliferative_Pathology]] [[Category:Expert_Review - Farm Animal]] [[Category:Oral_Diseases_-_Sheep]] [[Category:Dermatological_Diseases_-_Sheep]] [[Category:Oral_Diseases_-_Goat]] [[Category:Dermatological_Diseases_-_Goat]]
+====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