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Chronic Respiratory Disease.ppt

  1. CHRONIC RESPIRATORY DISEASE (CRD, AIR SACCULITIS, MG INFECTION) Is a slow spreading chronic upper and lower respiratory tract infection of chickens, turkeys (infectious sinusitis) and other birds (4-8 weeks)  Characterized by: • Rales (excessive mucous) • Coughing, gasping (struggle for breath) • Nasal discharge and rhinitis • Conjunctivitis • Air sacculitis
  2. ETIOLOGY Mycoplasma gallisepticum Family: Enterobacteriaceae Characteristics: – Smallest self replicating prokaryote – 300 – 800 nm in size – Lacks rigid cell wall – Highly pleomorphic – Coccoid, coccobacillus and filamentous – G –ve
  3. TRANSMISSION  Between flocks Direct contact, carriers & droplets. Spread is slow between houses and pens suggesting that aerosols are not normally a major route of transmission. Fomites appear to a significant factor in transmission between farms  Within a flock Spread from bird to bird  Vertical transmission is present (35% of eggs infected)
  4. Factors influencing susceptibility  Infection more severe in stress conditions even vaccination stress  Recovered birds remain infected for life; subsequent stress may cause recurrence of disease  More severe in cold weather especially sudden change in weather  Young birds more severely affected than adults  Poor ventilation, overcrowding, damp litter, ammonia production, irritation to respiratory mucous membrane
  5. CLINICAL SIGNS  Nasal discharge, coughing, gasping and sneezing  Thin & weak birds with razor blade breasts  Shaking of head (encephalopathy)  Low feed intake and low FCR  Poor carcass quality (Stunting) and weight gain  Out break occurs between 4 – 8 weeks of age  CRD COMPLEX: Mixed infection with E. coli, ND,IB,ILT,IC cause serious losses
  6. PATHOGENESIS  Organism enters through respiratory tract, conjunctiva or via infected embryo  Localizes in epithelium of respiratory tract  Irritation and damage of tracheal lining, airsacs and lungs  Destruction of cilia  Secondary infection (bacterial & viral infections) CRD complex  Septicaemia
  7. POSTMORTEM LESIONS  Sinus mucosa is coated with turbid mucus  Excessive mucus in trachea  Cheesy material in bronchi  Consolidated spots in lungs  Airsacculitis, Air sacs are often cloudy and contain large amounts of exudate  Perihepatitis, pericarditis and salpingitis  Muscles are pale and flabby
  8. POSTMORTEM LESIONS Early stage Advanced stage CRD COMPLEX • Excess mucous in trachea. • Plugs or pus in trachea. • Perihepatitis and pericarditis (especially with secondary E. coli infection) • Consolidated and solid spots on lungs. • Muscles pale and flabby • Formation of a creamy color (fibrinous) layer over heart and liver. Thickness of layer will indicate the advancement of CRD stage. • Cheesy material in lungs • Catarrhal inflammation of nasal passages, sinuses, trachea and bronchi. • Air sacculitis i.e. inflammation of air sacs • Occassionally arthritis and salpingitis in chickens. • Beaded or Lymph-follicular appearance. • Caseous exudate in air sacs. "Foamy or
  9. DIAGNOSIS  Field Clinical signs and lesions  Isolation and identification of organism  Sampling site:Upper respiratory tract (trachea)  Primary inoculation: • Frey’s medium • 0.1-1 mm smooth colonies with dense elevated centers  Serological identification Serum plate/ Tube agglutination test Haemagglutination inhibition test Antigen capture ELISA  Molecular diagnosis PCR Commercial kits available
  10. DIFFERENTIAL DIAGNOSIS • Newcastle disease • Infectious bronchitis • Infectious laryngotracheitis • Infectious coryza
  11. CONTROL 1. Ideally maintain Mycoplasma-free flock 2. Medications of breeders to eliminate egg transmission. 3. Before purchasing chicks from a hatchery, it should be confirmed that they are free from CRD 4. Blood serum testing of breeder chickens for MG antibodies has become a routine to test flocks for a MG infection 5. Before coming in contact with flocks, workmen should take shower and put on special clothes 6. Strict biosecurity measures should be adopted 7. Egg dipping in antibiotic solutions e g, Tylosin 8. Antibiotic therapy to chicks 9. Disposing of dead birds by incineration, deep burial or by means of special disposal pits.
  12. Severe gasping in chicks originated from infected breeding flocks
  13. Cheesy pus in the thoracic air sacs
  14. Airsacculitis
  15. Airsacculitis
  16. Swelling of the paranasal sinuses in turkeys
  17. Swelling of the paranasal sinuses in turkeys
  18. Acute foamy air sacculitis
  19. Creamy colour (fibrinous) layer formation due to MG associated with secondary bacterial infection
  20. Cloudy appearance of the abdominal air sacs
  21. MYCOPLASMA SYNOVIAE  Chronic subclinical upper respiratory infection  Characterized by swollen joints (hock)  Viscous creamy to grey exudate in synovial membranes, tendon sheaths and joints  Synovitis  Bursitis  Hepatitis  Hepatomegaly  Spleenomegaly