Changes

''A.suis'' is a beta-haemolytic Gram-negative bacterium.  Strains of ''A.Suis'' vary due to differences in their lipopolysaccharides (LPS), which is known as the 'O' antigen and is referred to as O1,O2 and O3 and capsules (CPS), called 'K' antigen with variants described as K1, K2 and K3.  

''A.suis'' is a beta-haemolytic Gram-negative bacterium.  Strains of ''A.Suis'' vary due to differences in their lipopolysaccharides (LPS), which is known as the 'O' antigen and is referred to as O1,O2 and O3 and capsules (CPS), called 'K' antigen with variants described as K1, K2 and K3.  

In piglets aged 1 to 8 weeks old the organism causes acute and rapidly fatal septicaemia, and localized infections such as endocarditis, polyarthritis, and respiratory distress may also been seen with additional neurological signs. Adult pigs can suffer pneumonia like symptoms, see [[Actinobacillus suis| clinical signs]] for more details. Although ''A.suis'' mainly affects pigs it has also been linked to septicaemia, acute haemorrhagic pulmonary infarction and necrotizing pneumonia in horses, airsaculitis in waterfowl, neonatal calf pneumonia and localised infections and polyarthritis in alpacas.  It is not considered a zoonosis but there has been a report of human infection after a pig bite <ref>Escande, F., Bailly, A., Bone, S., Lemozy, J. (1996)'''Actinobacillus suis infection after a pig bite'''. '''''Lancet''''' (British edition), 348(9031):888; 5 ref</ref>.

In piglets aged 1 to 8 weeks old the organism causes acute and rapidly fatal septicaemia, and localized infections such as endocarditis, polyarthritis, and respiratory distress may also been seen with additional neurological signs. Adult pigs can suffer pneumonia like symptoms, see [[Actinobacillus suis#Clinical Signs| clinical signs]] for more details. Although ''A.suis'' mainly affects pigs it has also been linked to septicaemia, acute haemorrhagic pulmonary infarction and necrotizing pneumonia in horses, airsaculitis in waterfowl, neonatal calf pneumonia and localised infections and polyarthritis in alpacas.  It is not considered a zoonosis but there has been a report of human infection after a pig bite <ref>Escande, F., Bailly, A., Bone, S., Lemozy, J. (1996)'''Actinobacillus suis infection after a pig bite'''. '''''Lancet''''' (British edition), 348(9031):888; 5 ref</ref>.

''A.suis'' have genes that encode toxins similar to apxI and apxII of ''A. pleuropneumoniae'', but are less virulent as they produce less Apx toxins than [[Actinobacillus pleuropneumoniae| ''A. pleuropneumoniae'']].  Once an animal is infected with ''A.suis'' it can provide partial cross protection against ''A. pleuropneumoniae''.  

''A.suis'' have genes that encode toxins similar to apxI and apxII of ''A. pleuropneumoniae'', but are less virulent as they produce less Apx toxins than [[Actinobacillus pleuropneumoniae| ''A. pleuropneumoniae'']].  Once an animal is infected with ''A.suis'' it can provide partial cross protection against ''A. pleuropneumoniae''.  

==Signalment==

==Signalment==

High health status herds with lower immune challenges are more at risk then conventional herds.  Piglets from high health status herds can suddenly die without any premonitory signs. Excessive temperature fluctuation, high humidity, mixing of pigs of different ages and overcrowding may also have an important role in the development of disease.

High health status herds with lower immune challenges are more at risk then conventional herds.  Piglets from high health status herds can suddenly die without any premonitory signs. Excessive temperature fluctuation, high humidity, mixing of pigs of different ages and overcrowding may also have an important role in the development of disease.

==Clinical Signs==

==Clinical Signs==

Clinical signs vary from fever, lethargy, depression, erysipelas-like lesions, abscesses, haemorrhage, vomiting/regurgitation and lameness and multiple joint swelling.  More serious cases progress to pneumonia (clinical signs similar to [[Actinobacillus pleuropneumoniae#Clinical Signs| ''A. pleuropneumoniae'']]) and sudden death.  Cardiorespiratory signs include tachycardia, heart murmurs, purulent or serous occulonasal discharges, sneezing, coughing, abnormal lung sounds, dyspnoea, changes in heart rate and open mouthed breathing.  Aural purulent mucoid discharge and increased amounts of wax are present along with a foul odour.  Pigs can become deaf and are often found rubbing and scratching their ears. Affected animals are in a lot of pain and discomfort and which manifests as dysphagia lymphadenopathy , anorexia, and unthriftiness.  Pregnant sows can suffer from agalactia, mastitis, abortions, still births or weak piglets.

Clinical signs vary from fever, lethargy, depression, erysipelas-like lesions, abscesses, haemorrhage, vomiting/regurgitation and lameness and multiple joint swelling.  More serious cases progress to pneumonia (clinical signs similar to [[Actinobacillus pleuropneumoniae#Clinical Signs| ''A. pleuropneumoniae'']]) and sudden death.  Cardiorespiratory signs include tachycardia, heart murmurs, purulent or serous occulonasal discharges, sneezing, coughing, abnormal lung sounds, dyspnoea, changes in heart rate and open mouthed breathing.  Aural purulent mucoid discharge and increased amounts of wax are present along with a foul odour.  Pigs can become deaf and are often found rubbing and scratching their ears. Affected animals are in a lot of pain and discomfort and suffer from dysphagia, lymphadenopathy, anorexia, and unthriftiness.  In sows it can cause agalactia, mastitis, abortions, still births or weak piglets.

Neurological signs include head tilt, circling, temors, nystagmus, strabismus, decreased or absent menace response, ptosis, miosis or meiosis, photophobia, headshaking, opisthotonus, facial paralysis, paraparesis and ataxia.

Neurological signs include head tilt, circling, temors, nystagmus, strabismus, decreased or absent menace response, ptosis, miosis or meiosis, photophobia, headshaking, opisthotonus, facial paralysis, paraparesis and ataxia.

==Diagnosis==

==Diagnosis==