Difference between revisions of "Poxviruses"
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==Parapoxviruses== | ==Parapoxviruses== | ||
| + | ===Contagious ecthyma=== | ||
| + | *AKA contagious pustular dermatitis, Orf, etc | ||
| + | |||
| + | ===General information=== | ||
| + | *CE is an acute debilitating but rarely fatal skin disease of sheep, goats and incidentally of ruminants and humans. | ||
| + | *The disease is generally mild. | ||
| + | *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. | ||
| + | *PPV's generally exhibit a highly restricted host range but in all cases can also infect man. | ||
| + | |||
| + | ===Aetiological agent=== | ||
| + | *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. | ||
| + | |||
| + | ===Pathology=== | ||
| + | [[Image:f00358.jpg]] | ||
| + | |||
| + | ===Differential diagnosis=== | ||
| + | * Sheep pox: A more severe disease, it is characterized by elevated papules distributed diffusely over the skin surface. Inclusion bodies are often seen, but there is no down‑growth of epidermis. There is a 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. | ||
| + | * Blue‑tongue: 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. The crusts are not firmly attached. | ||
| + | * Foot and mouth disease: When lesions occur in the mouth. | ||
| + | |||
==Avipoxviruses== | ==Avipoxviruses== | ||
Revision as of 13:15, 1 August 2007
Introduction
Orthopoxviruses
Parapoxviruses
Contagious ecthyma
- AKA contagious pustular dermatitis, Orf, etc
General information
- CE is an acute debilitating but rarely fatal skin disease of sheep, goats and incidentally of ruminants and humans.
- The disease is generally mild.
- 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.
- PPV's generally exhibit a highly restricted host range but in all cases can also infect man.
Aetiological agent
- 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.
Pathology
Differential diagnosis
- Sheep pox: A more severe disease, it is characterized by elevated papules distributed diffusely over the skin surface. Inclusion bodies are often seen, but there is no down‑growth of epidermis. There is a 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.
- Blue‑tongue: 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. The crusts are not firmly attached.
- Foot and mouth disease: When lesions occur in the mouth.