Difference between revisions of "Actinobacillus pleuropneumoniae"

Revision as of 16:30, 20 February 2011

Contagious Porcine Pleuropneumonia especially of pigs under 6 months
Endemic in UK
12 serotypes causing the same disease
Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
Pathogenesis and pathogenicity:
- Virulent strains possess capsules which are antiphagocytic and immunogenic
- Fimbriae allow the bacteria to attach to cells of the respiratory tract
- Damaged neutrophils in the lungs produce lytic enzymes
- The sustained inflammatory response causes tissue necrosis
- Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
- Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family
- RTX toxins:
  - Several peptide repeats within the molecules
  - Produced by various Gram-negative bacteria
  - Possess four contiguous genes, A, B, C and D
  - A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product
  - ApxI is a strong haemolysin with cytolytic activity
  - ApxII is a weak haemolysin
  - ApxIII is a cytotoxin
  - Different Actinobacillus pleuropneumonia serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III
  - Toxins introduce pores into cell membranes

Causative agent: Actinobacillus pleuropneumoniae
Expolsive outbreaks of pneumonia
Spread by direct contact and aerosol
Lesions
- Largely from toxin produced
- In diphragmatic lobes of the lungs
Haemorrhage with fibrinous pleuritis
Usually localised, sometimes generalised

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+*[[Contagious Porcine Pleuropneumonia]] especially of pigs under 6 months
-Causes: '''''Contagious Porcine Pleuropneumonia'''''
+*Endemic in UK
+*12 serotypes causing the same disease
+*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
+*Pathogenesis and pathogenicity:
+**Virulent strains possess capsules which are antiphagocytic and immunogenic
+**Fimbriae allow the bacteria to attach to cells of the respiratory tract
+**Damaged [[Neutrophils|neutrophils]] in the lungs produce lytic enzymes
+**The sustained inflammatory response causes tissue necrosis
+**Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
+**Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX)  cytolysin family
+**RTX toxins:
+***Several peptide repeats within the molecules
+***Produced by various Gram-negative bacteria
+***Possess four contiguous genes, A, B, C and D
+***A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product
+***ApxI is a strong haemolysin with cytolytic activity
+***ApxII is a weak haemolysin
+***ApxIII is a cytotoxin
+***Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III
+***Toxins introduce pores into cell membranes
-Previously known as: ''Haemophilus pleuropneumonia''
+*Causative agent: ''[[Actinobacillus pleuropneumoniae]]''
-== Introduction ==
+*Expolsive outbreaks of [[Pneumonia Overview#Infectious causes of pneumonia|pneumonia]]
+*Spread by direct contact and aerosol
+*Lesions
+**Largely from toxin produced
+**In diphragmatic lobes of the lungs
+*Haemorrhage with [[Pleuritis|fibrinous pleuritis]]
+*Usually localised, sometimes generalised
-Contagious Porcine Pleuropneumonia is a highly contagious and often fatal respiratory disease, seen in weanlings, growers and finishers ranging from 6 weeks to 6 months. It also causes abortion in sows and will cause milder respiratory signs in pigs of all ages. It is endemic in the UK.
-The presence of ''Actinobacillus'' in the lungs causes a [[Pleuritis|fibrinous pleurisy]] and [[:Category:Pneumonia|pneumonia]].
-It is a disease of acute onset in naive/ susceptible herds and can cause high morbidity and mortality (up to 50%). Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic.
+[[Category:Actinobacillus_species]][[Category:Pig Bacteria]]
+[[Category:To_Do_-_Bacteria]]
-The disease is transmitted by carrier pigs or new pigs brought into the herd and is spread by direct contact or aerosol transmission.
+[[Category:Respiratory_Bacterial_Infections]]
-==Pathogenesis==
-There are 12 serotypes causing the same disease. Different serotypes occur in different regions, with serotypes 3,6 and 8 the most common in the UK.
-Virulent strains possess capsules which are antiphagocytic and immunogenic. Fimbriae allow the bacteria to attach to cells of the respiratory tract. Damaged [[Neutrophils|neutrophils]] in the lungs produce lytic enzymes. The sustained inflammatory response causes tissue necrosis. Lungs become consolidated and necrotic with fibrinous pleurisy at post mortem.
-The bacteria produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family. There are several peptide repeats within the molecules. The toxins are produced by various Gram-negative bacteria. There are four contiguous genes, A, B, C and D. A is the structural gene; B and D are required for secretion; C
-allows post-translational activation of the gene product of A into a functional product.
-*ApxI is a strong haemolysin with cytolytic activity
-*ApxII is a weak haemolysin
-*ApxIII is a cytotoxin
-Different ''Actinobacillus pleuropneumonia'' serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III. Toxins introduce pores into cell membranes.
-== Clinical signs ==
-In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic. There will often be presence of blood-stained froth surrounding nose and mouth. Cyanosis follows later along with a sub-normal rectal temperature; death will then ensue. Pregnant sows will abort.
-In subacute outbreaks, some pigs will be found dead but others in the group may show varying degrees of exercise intolerance and respiratory distress.
-== Diagnosis ==
-Clinical signs especially if in the acute form are suggestive of this diagnosis as [[Swine Influenza|influenza]] rarely causes mortality and does not primarily affect young pigs.
-The post mortem findings will confirm the diagnosis. The lesions are largely caused by the toxins produced. These will include; haemorrhagic consolidation close to the main bronchi or the diaphragmatic lung lobe, which is usually localised. Necrosis and fibrinous pleuritis may also be visible. Lung scarring and pleural adhesions may have developed in recovered animals.
-Samples can be cultured on chocolate agar and diagnosed by immunofluorescent or PCR-based techniques. The bacteria on the [[Tonsils - Anatomy & Physiology#Palatine|palatine tonsil]] may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs.
-== Treatment and Control ==
-Antibiotics should be administered as soon as clinical signs are suggestive of the disease. Water and feed intake is usually very reduced so in-water or in-feed treatments are of little use and treatment should be administered parenterally. Prophylactic antibiotics may be used for in-contact pigs.
-As a control mechanism, killed and polyvalent bacterin [[Vaccines|vaccines]] as well as a subunit vaccine are available. They are given as two injections, two weeks apart to pigs no younger than six weeks of age. The sow can also be vaccinated pre and early pregnancy to allow passive immunity to occur.
-Isolation on farms using all in all out systems will also dramatically reduce signs of infection, although not prevent it. Hygiene should be improved by improving ventilation and avoiding chilling and overcrowding.
-{{Learning
-|literature search = [http://www.cabdirect.org/search.html?q=title%3A%28%22Haemophilus+pleuropneumonia%22%29 ''Haemophilus pleuropneumonia'' publications]
-}}
-== References ==
-Cowart, R.P. and Casteel, S.W. (2001) An Outline of Swine diseases: a handbook Wiley-Blackwell
-Jackson, G.G. and Cockcroft, P.D. (2007) Handbook of Pig Medicine Saunders Elsevier
-Shope Richard E, White David C, Leidy Grace. PORCINE CONTAGIOUS PLEUROPNEUMONIA : II. STUDIES OF THE PATHOGENICITY OF THE ETIOLOGICAL AGENT, HEMOPHILUS PLEUROPNEUMONIAE. J Exp Med. 1964 Feb
-Straw, B.E. and Taylor, D.J. (2006) Disease of Swine Wiley-Blackwell <br>Taylor, D.J. (2006) Pig Diseases (Eighth edition) St Edmunsdbury Press ltd
-{{review}}
-{{OpenPages}}
-[[Category:Actinobacillus_species]] [[Category:Pig_Bacteria]] [[Category:Respiratory_Bacterial_Infections]] [[Category:Respiratory_Diseases_-_Pig]] [[Category:Expert_Review - Farm Animal]]

Difference between revisions of "Actinobacillus pleuropneumoniae"

Revision as of 16:30, 20 February 2011

Navigation menu

Search