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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 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. It causes Actinobacillosis in [[Actinobacillosis - Pig| pigs]], [[Actinobacillus equuli| horses]],[[Actinobacillosis - Cattle| cattle]] and can infect [[Actinobacillus suis#signalment| various other species. |
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| − | 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>.
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| | ''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''. |
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| | ==Signalment== | | ==Signalment== |
| − | ''A.Suis'' can be found worldwide in both healthy and diseased animals which are genetically and biochemically similar. It is believed to be spread via aerososl infection and invasion of the upper respiratory tract. Wild hosts include anatidae (ducks, geese and swans) and [http://en.wikipedia.org/wiki/ Coypu] but A.suis can also affect domestic species including dogs, cats, [[Actinobacillus equuli| horses]], [[Actinobacillosis - Cattle| cattle]], sheep, goats, alpacas and zebu. | + | ''A.Suis'' can be found worldwide in both healthy and diseased animals which are genetically and biochemically similar. It is believed to be spread via aerososl infection and invasion of the upper respiratory tract. Wild hosts include anatidae (ducks, geese and swans) and [http://en.wikipedia.org/wiki/ Coypu] but A.suis can also affect domestic species including pigs, [[Actinobacillus equuli| horses]], [[Actinobacillosis - Cattle| cattle]], sheep, goats, alpacas, zebu, dogs, and cats. |
| − | 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.
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| − | ==Clinical Signs==
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| − | 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.
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| − | 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.
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| − | ==Diagnosis==
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| − | [[File:Actinobacillus suis.jpg|thumb|200px|right| Actinobacillus suis. Gram stain]]
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| − | Diagnosis can be difficult as its clinical signs are similar to other pathogens, such as ''Streptococcus suis'' and ''Haemophilus parasuis'', both being able to induce a septicaemic infection with sudden death. Infection can be confirmed by the isolation of ''A. suis'', from culturing infected tissue. On post-mortem serous or fibrinous exudates can be found in the thorax and pericardium and ecchymotic haemorrhages can be seen in kidneys, lungs, liver, spleen and other organisms.
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| − | '''Differential diagnosis''': [[Actinobacillus pleuropneumoniae| ''A. pleuropneumoniae'']], [[Erysipelas - Pig|''Erysipelas'']], [[Glasser's Disease| ''Glasser’s disease'']], [[Streptococcus suis| ''Streptococcus suis'']], and [[Mulberry Heart Disease| ''Mulberry heart disease'']].
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| − | ==Treatment==
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| − | ''A.suis'' has good sensitivity to ceftioufur, gentamicin and trimethoprim/sulfadiazine, and moderate sensitivity to ampicillin, neomycin, sulfadimethoxine and tiamulin. Culture and sensitivity is recommended.
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| − | ==Control==
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| − | Routine biosecurity and disinfection should be followed and maintained. At present there is no commercial vaccine for ''A. suis'' <ref>Radostitis, O.M., Gay, C.C., Hinchcliff, K.W., and Constable, P.D. (2007). '''Veterinary Medicine: A textbook of the diseases of cattle, horses, sheep, pigs and goats (10th Edition)'''. '''''Saunders''''', 1052-1053.</ref> but there is evidence that autogenous vaccines in a herd could help stabilize antibody levels in the whole population <ref>Lapointe, L., D'Allaire, S., Lacouture, S., Gottschalk, M. (2001). '''Serologic profile of a cohort of pigs and antibody response to an autogenous vaccine for Actinobacillus suis'''. '''''Veterinary Research''''', 32(2):175-183; 18 ref.</ref>.
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| − | ==References==
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| − | <references/>
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