Classical Swine Fever - Revision history

Bara at 14:57, 15 October 2013

2013-10-15T14:57:18Z

Bara at 13:33, 10 May 2011

2011-05-10T13:33:03Z

Bara: Text replace - "Category:Expert Review - Farm Animal" to "Category:Brian Aldridge reviewing"

2011-03-02T12:26:12Z

Text replace - "Category:Expert Review - Farm Animal" to "Category:Brian Aldridge reviewing"

Bara: /* References */

2011-02-26T16:15:30Z

References

Bara: Text replace - "[[Haemorrhage - Pathology" to "[[Haemorrhage"

2011-02-14T14:54:58Z

Text replace - "[[Haemorrhage - Pathology" to "[[Haemorrhage"

Bara at 18:33, 17 January 2011

2011-01-17T18:33:01Z

Suzannah.stacey: /* Transmission and Pathogenesis */

2010-10-20T09:55:16Z

Transmission and Pathogenesis

Suzannah.stacey at 09:54, 20 October 2010

2010-10-20T09:54:27Z

Suzannah.stacey at 09:45, 20 October 2010

2010-10-20T09:45:21Z

Suzannah.stacey: /* Laboratory Tests */

2010-10-18T18:05:26Z

Laboratory Tests

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 Wild boar act as a reservoir of CSF infection, and so control must also be aimed at this population. As well as adequate surveillance, this involves utilising knowledge about factors influencing CSF epidemiology such as wild boar behaviour and population dynamics, and the influence of hunting strategies.  Wild boar vaccination schemes are currently being undertaken in parts of Europe using bait containing marker vaccines.
-==Literature Search==
+{{Learning
-[[File:CABI logo.jpg|left|90px]]
+|literature search = [http://www.cabdirect.org/search.html?q=title%3A%28%22Classical+Swine+Fever%22%29+AND+%28title%3A%28transmission%29+OR+title%3A%28pathogenesis%29%29 Classical Swine fever transmission and/or pathogenesis publications]
 [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=%22classical+swine+fever%22&occuring1=title&rowId=2&options2=AND&q2=&occuring2=de&rowId=3&options3=AND&q3=&occuring3=freetext&publishedstart=2000&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all&x=42&y=10 Classical Swine Fever publications since 2000]
 ==Links==
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 [[Category:Pig Viruses]][[Category:Lymphoreticular and Haematopoietic Diseases - Pig]][[Category:Neurological Diseases - Pig]][[Category:Dermatological Diseases - Pig]][[Category:Intestinal Diseases - Pig]][[Category:Respiratory Diseases - Pig]][[Category:Musculoskeletal Diseases - Pig]]
 [[Category:Brian Aldridge reviewing]]

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-{{review}}
+Also known as: '''''CSF — Hog Cholera — Pig Plague — CSFV
 ==Introduction==
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 #Paton, DJ and Greiser-Wilke, I (2003) '''Classical swine fever – an update''', ''Research in Veterinary Science'', 75, 169-178.
 [[Category:Pestiviruses]][[Category:Haemorrhagic Diseases]][[Category:Enteritis,_Viral]][[Category:Enteritis,_Ulcerative]]
 [[Category:Pig Viruses]][[Category:Lymphoreticular and Haematopoietic Diseases - Pig]][[Category:Neurological Diseases - Pig]][[Category:Dermatological Diseases - Pig]][[Category:Intestinal Diseases - Pig]][[Category:Respiratory Diseases - Pig]][[Category:Musculoskeletal Diseases - Pig]]
 [[Category:Brian Aldridge reviewing]]

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 [[Category:Pestiviruses]][[Category:Haemorrhagic Diseases]][[Category:Enteritis,_Viral]][[Category:Enteritis,_Ulcerative]]
 [[Category:Pig Viruses]][[Category:Lymphoreticular and Haematopoietic Diseases - Pig]][[Category:Neurological Diseases - Pig]][[Category:Dermatological Diseases - Pig]][[Category:Intestinal Diseases - Pig]][[Category:Respiratory Diseases - Pig]][[Category:Musculoskeletal Diseases - Pig]]
-[[Category:Expert Review - Farm Animal]]
+[[Category:Brian Aldridge reviewing]]

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 [[Category:Pestiviruses]][[Category:Haemorrhagic Diseases]][[Category:Enteritis,_Viral]][[Category:Enteritis,_Ulcerative]]
 [[Category:Pig Viruses]][[Category:Lymphoreticular and Haematopoietic Diseases - Pig]][[Category:Neurological Diseases - Pig]][[Category:Dermatological Diseases - Pig]][[Category:Intestinal Diseases - Pig]][[Category:Respiratory Diseases - Pig]][[Category:Musculoskeletal Diseases - Pig]]
-[[Category:Expert_Review]]
+[[Category:Expert Review - Farm Animal]]

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 Although the incubation period for classical swine fever is generally less than ten days, in the field it may take up to four weeks for clinical signs to become apparent in a population. Disease severity varies with virulence, immune status and the age of the animal: this means that although acute, chronic and congenital forms of the disease can be appreciated, there is no "classic" disease presentation.
-In the '''acute form''', animals are almost always pyrexic. In piglets the fever may exceed 40<sup>0</sup>C, but in adults temperatures may be no higher than 39.5<sup>0</sup>C. Lethargy, conjunctivitis and lymphomegaly may be seen, as well as respiratory signs and diarrhoea. Neurological signs such as gait abnormalities, incoordination and convulsions are also common. The most telling sign of classical swine fever is haemorrhage of the skin. Haemorrhages arise in the second or third week post-infection on the ear, tail, abdomen and medial aspect of the limbs and persist until death. CSF virus also causes severe leukopenia and immunosuppression, leading to secondary enteric or respiratory infections which may cause confusion by masking or overlapping the more typical signs of CSF. The clinical signs of acute CSF become less specific and diagnosis more difficult as the age of onset increases. Also, acute classical swine fever is clinically indistinguishable from African swine fever and so care must be taken when formulating a diagnosis. Other differential diagnoses for acute CSF are [[Erysipelas - Pig|erysipelas]], [[Porcine Reproductive and Respiratory Syndrome|PRRS]], [[Haemorrhage - Pathology#Purpura|purpura haemorragica]], [[Porcine Circoviruses|PMWS, PDNS]], [[Salmonellosis]] and [[Pasteurellosis - Pigs|Pasteurellosis]]. Classical swine fever should also be considered in any pyrexic enteric or respiratory disease case that is not responsive to antibiotics.
+In the '''acute form''', animals are almost always pyrexic. In piglets the fever may exceed 40<sup>0</sup>C, but in adults temperatures may be no higher than 39.5<sup>0</sup>C. Lethargy, conjunctivitis and lymphomegaly may be seen, as well as respiratory signs and diarrhoea. Neurological signs such as gait abnormalities, incoordination and convulsions are also common. The most telling sign of classical swine fever is haemorrhage of the skin. Haemorrhages arise in the second or third week post-infection on the ear, tail, abdomen and medial aspect of the limbs and persist until death. CSF virus also causes severe leukopenia and immunosuppression, leading to secondary enteric or respiratory infections which may cause confusion by masking or overlapping the more typical signs of CSF. The clinical signs of acute CSF become less specific and diagnosis more difficult as the age of onset increases. Also, acute classical swine fever is clinically indistinguishable from African swine fever and so care must be taken when formulating a diagnosis. Other differential diagnoses for acute CSF are [[Erysipelas - Pig|erysipelas]], [[Porcine Reproductive and Respiratory Syndrome|PRRS]], [[Haemorrhage#Purpura|purpura haemorragica]], [[Porcine Circoviruses|PMWS, PDNS]], [[Salmonellosis]] and [[Pasteurellosis - Pigs|Pasteurellosis]]. Classical swine fever should also be considered in any pyrexic enteric or respiratory disease case that is not responsive to antibiotics.
 The '''chronic form''' of classical swine fever develops when pigs fail to mount an effective immune response to viral infection. Initially, the signs are similar to the acute form of the disease, but symptoms become less specific as the course progresses. For example, pigs may display chronic enteritis, loss of condition, lameness or intermittent pyrexia. In a herd, mortality may be increased or there may be large numbers of runty pigs. Although animals may survive some months after contracting chronic CSF, the disease is always eventually fatal and animals continue to shed virus until death.

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 ==Transmission and Pathogenesis==
-In field cases of CSFV, transmission is mainly oronasal by direct or indirect contact with infected pigs. Infected feed or pork products may also cause spread of disease, and transmission in semen can occur. Once the virus gains entry to the host an incubation period of around 7 days occurs prior to the onset of clinical signs, but this may vary from 4-10 days. Initially, virus infects the epithelial cells of the tonsillar crypts before spreading via the lymphatics to regional lymph nodes. From here, the virus enters the blood stream and then replicates in the spleen, bone marrow and lymph nodes before spreading to other tissues. Replication in the endothelial cells of blood vessels leads to apoptosis, causing superficial and internal haemorrhages. CSFV also induces a [[thrombocytopenia]] which contributes to haemorrhage by impairing primary [[Normal Mechanisms of Haemostatic Control|haemostasis]]. In acute CSF this angiopathy, in association with shock and pyrexia, leads to death. Surviving swine go on to develop a chronic form of the disease where tissue infarction results in joint and enteric lesions.
+In field cases of CSFV, transmission is mainly oronasal by direct or indirect contact with infected pigs. Infected feed or pork products may also cause spread of disease, and transmission in semen can occur. Once the virus gains entry to the host an incubation period of around 7 days occurs prior to the onset of clinical signs, but this may vary from 4-10 days. Initially, virus infects the epithelial cells of the tonsillar crypts before spreading via the lymphatics to regional lymph nodes. From here, the virus enters the blood stream and then replicates in the spleen, bone marrow and lymph nodes before spreading to other tissues. Replication in the endothelial cells of blood vessels leads to apoptosis, causing superficial and internal haemorrhages. CSFV also induces a [[thrombocytopenia]] which contributes to haemorrhage by impairing primary [[Normal_Mechanisms_of_Haemostatic_Control#Introduction|haemostasis]]. In acute CSF this angiopathy, in association with shock and pyrexia, leads to death. Surviving swine go on to develop a chronic form of the disease where tissue infarction results in joint and enteric lesions.
 The outcome of transplacental infection depends largely on the point of gestation and may result in abortions, stillbirths, mummifications, malformations or the birth of weak or persistently viraemic piglets. Although persistently infected piglets may be clinically normal at birth, they grow poorly, excrete virus over long periods and invariably die eventually from full blown CSF.

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 Laboratory testing is required to confirm a diagnosis of classical swine fever. As well as collection of tissues for histopathology, samples of tonsils, spleen, lymph nodes, kidney and distal ileum are taken for virus detection. Virus may be detected by fluorescent antibody detection, ''in situ'' hybridisation, PCR, immunoperoxidase staining or virus isolation. Several of these methods are reviewed by Moennig<sup>1</sup>, and are briefly summarised here.
-The gold standard laboratory test for CSFV is '''virus isolation in cell culture'''. In viraemic animals, virus may be isolated both from buffy coat cells and from suspensions of spleen, lymph node, tonsil, kidney or parotid salivary glands. Samples are incubated on cultures of porcine cells, and since classical swine fever virus is non-cytopathogenic, anti-CSFV antibodies are used to detect virus. Despite good specificity and sensitivity, the virus isolation process takes around three days and is labour intensive and therefore costly. [[Immunofluorescence|'''Fluorescent antibody testing''']] is less sensitive but more rapid than virus isolation, and involves the used of fluoresecently-labelled anti-CSFV antibodies to demonstrate the presence of virus antigen in tissue. A virus antigen capture [[ELISA testing|'''ELISA''']] also established the presence of antigen through the use of specific antibodies, and is useful for screening large numbers of animals.  In the last ten years, it has become possible to detect CSF virus RNA by '''RT-PCR''', usually of the 5' untranslated region. As well as confirming infection, this allows subsequent genetic sequencing and differentiation between isolates.
+The gold standard laboratory test for CSFV is '''virus isolation in cell culture'''. In viraemic animals, virus may be isolated both from buffy coat cells and from suspensions of spleen, lymph node, tonsil, kidney or parotid salivary glands. Samples are incubated on cultures of porcine cells, and since classical swine fever virus is non-cytopathogenic, anti-CSFV antibodies are used to detect virus. Despite good specificity and sensitivity, the virus isolation process takes around three days and is labour intensive and therefore costly. [[Immunofluorescence|'''Fluorescent antibody testing''']] is less sensitive but more rapid than virus isolation, and involves the used of fluoresecently-labelled anti-CSFV antibodies to demonstrate the presence of virus antigen in tissue. A virus antigen capture [[ELISA testing|'''ELISA''']] also establishes the presence of antigen through the use of specific antibodies, and is useful for screening large numbers of animals.  In the last ten years, it has become possible to detect CSF virus RNA by '''RT-PCR''', usually of the 5' untranslated region. As well as confirming infection, this allows subsequent genetic sequencing and differentiation between isolates.
-Although antigen detection methods have largely replaced serology in the diagnosis of acute classical swine fever outbreaks, CSFV '''serology''' is important for disease surveillance, particularly in wild boar. A virus neutralisation test is the most sensitive and specific form of CSFV serology, and involved incubation of test sera with a CSFV to neutralise any anti-CSFV antibodies present. However, the virus neutralisation test takes several days, and so an ELISA test may be used when large numbers of samples must be processed.
+Although antigen detection methods have largely replaced serology in the diagnosis of acute classical swine fever outbreaks, CSFV '''serology''' is important for disease surveillance, particularly in wild boar. A virus neutralisation test is the most sensitive and specific form of CSFV serology, and involves incubation of test sera with a CSFV to neutralise any anti-CSFV antibodies present. The virus neutralisation test takes several days, and so an ELISA test may be used when large numbers of samples must be processed urgently.
 ==Treatment==