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==Introduction==

==Introduction==

''A.suis'' is a beta-haemolytic '''Gram-negative bacterium'''.  Strains of ''A.suis'' vary due to differences in their '''lipopolysaccharides (LPS)''', which are known as ''''O' antigens''' and are referred to as '''O1,O2''' and '''O3''' and '''capsules (CPS)''', refered to as''''K' antigen''' with variants described as '''K1, K2''' and '''K3'''. More than 95% of A. suis clinical isolates are cross-reactive with O1/K1 or O2/K3 antiserum and more severe infection were noted with O2/K2 srain <ref name="Slavic et al., 2000">Slavic, D., DeLay, J., Hayes, M.A., MacInnes, J.I.(2000) '''Comparative pathogenicity of different Actinobacillus suis O/K serotypes'''. ''Canadian Journal of Veterinary Research'', 64(2):81-87.</ref>.  This '''opportunistic''' bacteria mainly causes [[Actinobacillosis - Pig| '''actinobacillosis in pigs''']], but has also been linked to diseases in neonatal calfs, waterfowl, alpacas, horses and [[Actinobacillus suis#signalment| various other species]].

''A.suis'' is a beta-haemolytic '''Gram-negative bacterium'''.  It has many strains due to differences in their '''lipopolysaccharides (LPS)''', which are known as ''''O' antigens''' and are referred to as '''O1,O2''' and '''O3''' and '''capsules (CPS)''', refered to as''''K' antigen''' with variants described as '''K1, K2''' and '''K3'''. More than 95% of A. suis clinical isolates are cross-reactive with O1/K1 or O2/K3 antiserum and more severe infection were noted with O2/K2 srain <ref name="Slavic et al., 2000">Slavic, D., DeLay, J., Hayes, M.A., MacInnes, J.I.(2000) '''Comparative pathogenicity of different Actinobacillus suis O/K serotypes'''. ''Canadian Journal of Veterinary Research'', 64(2):81-87.</ref>.  This '''opportunistic''' bacteria mainly causes [[Actinobacillosis - Pig| '''actinobacillosis in pigs''']], but has also been linked to diseases in neonatal calfs, waterfowl, alpacas, horses and [[Actinobacillus suis#signalment| various other species]].

Other haemolytic strains of ''Actinobacillus species'' have been linked to various diseases in horses such as [[Actinobacillus equuli| ''Actinobacillus equuli'']] and [[Actinobacillosis - Cattle|''Actinobacillus ligneresii'']]. The latter species also causes [[Actinobacillosis - Cattle|wooden tongue in cattle]].  

Other haemolytic strains of ''Actinobacillus species'' have been linked to various diseases in horses such as [[Actinobacillus equuli| ''Actinobacillus equuli'']] and [[Actinobacillosis - Cattle|''Actinobacillus ligneresii'']]. The latter species also causes [[Actinobacillosis - Cattle|wooden tongue in cattle]].  

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

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

==Signalment==

==Signalment==

==Epidemiology==

==Epidemiology==

The epidemiology of ''A.Suis'' is poorly understood.  ''A.Suis'' can be found in the tonsils and upper respiratory tract of both healthy and diseased pigs, and isolates are genetically and biochemically similar.  It is believed to be spread via '''aerososl infection''' and '''invasion of the upper respiratory tract'''. It is thought to colonise piglets in the first three weeks of life but not all piglets become clinically affected and some can become carriers.  

The epidemiology of ''A.Suis'' is poorly understood, although it can be found in the tonsils and upper respiratory tract of both healthy and diseased pigs, and isolates are genetically and biochemically similar.  It is believed to be spread via '''aerososl infection''' and '''invasion of the upper respiratory tract'''. It is thought to colonise piglets in the first three weeks of life but not all piglets become clinically affected and some can become carriers.  

    

    

==Diagnosis==

==Diagnosis==

''A.Suis'' is difficult to culture and most of the O1 strains analyzed possess '''pustulan''' (1-6,beta-D-glucan)which is a major component of fungal and lichen cell walls. Therefore, many animals have antibodies to this polysaccharide in the absence of exposure to A. suis.  These antibodies may provide naive pigs with some level of protection against the O1 strains <ref name="MacInnes and Desrosiers, 1999">MacInnes, J.I., Desrosiers, R.(1999)''' Agents of the "suis-ide diseases" of swine: Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis'''. ''Canadian Journal of Veterinary Research'', 63(2):83-89; 52 ref.</ref>, <ref name="Slavic et al., 2000"/>.  For more information see [[Actinobacillosis - Pig| '''actinobacillosis in pigs''']].

''A.Suis'' is difficult to culture and most of the O1 strains analyzed possess '''pustulan''' (1-6,beta-D-glucan)which is a major component of fungal and lichen cell walls. Therefore, many animals have antibodies to this polysaccharide in the absence of exposure to ''A. suis''.  These antibodies may provide naive pigs with some level of protection against the O1 strains <ref name="MacInnes and Desrosiers, 1999">MacInnes, J.I., Desrosiers, R.(1999)''' Agents of the "suis-ide diseases" of swine: Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis'''. ''Canadian Journal of Veterinary Research'', 63(2):83-89; 52 ref.</ref>, <ref name="Slavic et al., 2000"/>.  For more information see [[Actinobacillosis - Pig| '''actinobacillosis in pigs''']].

==Distribution==

==Distribution==