Sheeppox
Sheeppox virus | |
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Bacilli of malignant edema and in cornea of pox in sheep | |
Virus classification | |
(unranked): | Virus |
Realm: | Varidnaviria |
Kingdom: | Bamfordvirae |
Phylum: | Nucleocytoviricota |
Class: | Pokkesviricetes |
Order: | Chitovirales |
Family: | Poxviridae |
Genus: | Capripoxvirus |
Species: | Sheeppox virus
|
Synonyms[1] | |
Sheep pox virus |
Sheeppox (or sheep pox, known as variola ovina in
Goatpox is a similar disease of goats, caused by a virus antigenically distinct from sheeppox virus.
Virology
Structure
Sheeppox virus is approximately 150 kbp and shares 96% and 97% nucleotide identity with goatpox virus and lumpy skin disease virus, respectively.[3] This virus has a linear, dsDNA genome and is thus a part of group I according to the Baltimore Classification System. The virus has a complex coat and capsid symmetry.[citation needed]
Host
The hosts for sheeppox virus are all breeds of wild and domesticated sheep. However, those animals native to the region where SPV is endemic, are far less susceptible. Young, lactating, and older animals are more susceptible to this viral infection though no viral preference has been found. This virus is endemic to Africa, Asia, India, and the Middle East.[4]
Replication
The virus enters the host cell via
The intermediate phase, approximately 100 minutes post infection, stimulates genomic replication as the intermediate genes are expressed. 140 minutes to 48 hours post infection is considered the late phase which is when all structural proteins are produced. Virion assembly begins in the cytoplasm with the formation of an immature spherical particle. Once maturation occurs, it is considered an intracellular mature virion. These are brick-shaped particles that can then be released from the cell either by budding or cell lysis.[5]
Transmission
Sheeppox virus is an aerosol and can also be transmitted via contact with an infected animal. The
Symptoms and diagnosis
Symptoms
Symptoms can range from mild to severe depending on things such as age, breed, and immunity of the host. The virulence of the virus is also a contributing factor. The incubation period of the virus is 4–12 days.
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Lesions around lips (orf is on lips)
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Starting lesions (reddening) in axilla
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Crusty lesions in axilla
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Crusty lesions on tail
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Crusty lesions on tail (lamb)
Early symptoms include increased temperature and
The acute phase is characterized as 24 hours after papule appearance. In this phase the sheep may develop rhinitis, conjunctivitis, and swollen lymph nodes, up to eight times the normal size. Blepharitis can result from papules on the eyelids, mucosa becomes necrotic, and ulcers on the mucous membranes may create discharge. Due to lymph node swelling and developing lung lesions, breathing can become loud and labored.[citation needed]
The acute phase has passed when the papules become
There have only been two reported cases of zoonotic transmission which result in a mild localized reaction limited to the skin.[8]
Diagnosis
Differential
Can include[4]
- Contagious pustular dermatitis(scabby mouth)
- Blue tongue
- Mycotic dermatitis
- Sheep scab
- Mange
- Photosensitisation
Laboratory
Samples can include[7]
- Full skin thickness biopsies
- Vesicular fluid if available
- Scabs
- Lymph node aspirates
- Lung and skin lesions
Techniques that can be used include
- Polymerase Chain Reaction (PCR)
- Agar gel immunodiffusion test (AGID)
- Enzyme-linked immunosorbent assay (ELISA)
- Transmission electron microscopy
- Virus isolation in cell culture
History
In the 20th century, sheeppox virus was eradicated from continental Europe, but since then, there have been sporadic outbreaks, which are most likely due to imported animals. The countries with the highest number of cases are Ethiopia (223), Somalia (170), and Algeria (44). This resulted in a 16.3% case fatality rate out of the 9932 cases involved. From 2010 to 2011 there was a 46% decrease in the number of outbreaks with no specific explanation for this decrease. There has been no seasonal variability identified.[8]
Outbreaks
A relatively recent
Most recently, in early September 2017, there have been 2 outbreaks of sheeppox virus in Greece. This current location had 3 previous outbreaks in January 2017 with the origin of infection unknown. Real time PCR results tested positive for SPV and the infected were removed from the population either through death, destruction, or slaughter. Measures that were taken in response to these outbreaks were proper disposal of the carcasses, movement control within the country, and quarantine.[9]
Prevention
There is no treatment for sheeppox virus, thus efforts are directed towards prevention.
Vaccines
The most effective control over the disease has been the
Sanitation
Cleaning of farms and equipment is important in helping to prevent the spread of SPV. Infected animals may be quarantined and new animals should be isolated from the infected herds while transmission is still possible. If necessary, slaughtering or euthanasia of the herd can help prevent further disease transmission. Crucial is the proper disposal of the animals, either by burning or burying them.[4][7]
References
- ^ 1ICTV 5thReportFrancki, R. I. B., Fauquet, C. M., Knudson, D. L. & Brown, F. (eds)(1991). Classification and nomenclature of viruses. Fifthreport of the International Committee on Taxonomy of Viruses. Archives of Virology Supplementum 2, 452 pp. https://ictv.global/ictv/proposals/ICTV%205th%20Report.pdf
- ^ ISBN 978-0-7020-0718-7.
- ^ PMID 12021338.
- ^ a b c d e "A100 - SHEEP POX AND GOAT POX". lrd.spc.int. Retrieved 2017-11-03.
- ^ "Capripoxvirus". viralzone.expasy.org. Retrieved 2017-11-03.
- ^ a b "Sheeppox and Goatpox - Integumentary System - Merck Veterinary Manual". Merck Veterinary Manual. Retrieved 2017-11-03.
- ^ a b c d "Search: OIE - World Organisation for Animal Health". www.oie.int. Retrieved 2017-11-03.
- ^ a b c d "sheep and goat pox". www.cabi.org. Retrieved 2017-11-03.
- ^ a b "ProMED-mail". www.promedmail.org. Retrieved 2017-11-03.