Difference between revisions of "Contagious Porcine Pleuropneumonia"

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== Synonyms ==
#redirect[[Actinobacillus pleuropneumoniae]]
[[Actinobacillus pleuropneumoniae]]
== Clinical signs ==
and epidemiology:
Acute disease in susceptible herds with high morbidity and mortality (up to 50%)
In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic
Blood-stained froth surrounding nose and mouth
Pregnant sows abort
Causes [[Respiratory Bacterial Infections - Pathology#Actinobacillus_pleuropneumoniae|pneumonia]] in pigs
Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic
Lung scarring and pleural adhesions in many recovered animals
Solid immunity develops in recovered animals to all serotypes
The disease is spread between herds by carrier pigs
**Haemorrhagic consolidation close to the main bronchi and fibrinous pleuritis may be suggestive
**Specimens are cultured on chocolate agar and blood agar in 5-10% carbon dioxide for 2-3 days
**Small colonies surrounded by clear haemolysis
**No growth on MacConkey agar
**Positive CAMP reaction with ''[[Staphylococcus aureus]]''
**Most strains are NAD-dependent (grow on Heated Blood agar)
**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
**Antibiotics depending on the strain of bacteria
**Prophylactic antibiotics for in-contact pigs
**Killed and polyvalent bacterin vaccines as well as a subunit vaccine are available
**Improve ventilation, avoid chilling and overcrowding
*Caused by [[Haemophilus pleuropneumonia|''Haemophilus (Actinobacillus) pleuropneumonia'']]
*Seen mainly between 6wks-6mths of age but will affect any age
*Highly pathogenic strains are capable of initiating disease on their own with high mortality in young pigs
*A fibrinonecrotic [[Bronchitis#Infectious_causes_of_bronchitis_or_bronchiolitis|broncho]][[Pneumonia Overview#Infectious_causes_of_pneumonia|pneumonia]] with [[Pleuritis|pleurisy]]
*Foci of haemorrhagic consolidation or necrosis, mainly around major bronchi, tend to sequestrate
*Tending to spread throughout all lung lobes: therefore a cranioventral distribution may not be particularly evident
*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|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 Overview#Infectious causes of pneumonia|pneumonia]]
*Spread by direct contact and aerosol
**Largely from toxin produced
**In diphragmatic lobes of the lungs
*Haemorrhage with [[Pleuritis|fibrinous pleuritis]]
*Usually localised, sometimes generalised
[[Category:Actinobacillus_species]][[Category:Pig Bacteria]]
[[Category:Respiratory_Diseases_-_Pig]] [[Category:To_Do_-_Kate]]

Latest revision as of 18:49, 14 March 2011