Infectious bursal diseaes


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Infectious bursal diseaes

  2. 2. DEFINITION <ul><li>DEFINITION IBD or Gumboro disease </li></ul><ul><li>is an acute (sudden & severe), highly contagious viral infection of young chicken </li></ul>
  3. 3. Disease is of economic importance for 2 reasons : <ul><li>1- it causes heavy mortality in the chickens of 3 weeks of age </li></ul><ul><li>2- It causes immunosuppression which leads to vaccination failure, E.coli infection, gangrenous dermatitis, & Inclusion body hepatitis </li></ul>
  4. 4. ETIOLOGY : <ul><ul><li>is a member of the Birnaviridae family Virus is single shelled Non enveloped virion </li></ul></ul>
  5. 5. Source Of Infection : <ul><li>Source Of Infection Infected houses remain infected for 122 days. Water, feed & dropping from infected pen remain infected for 52 days. Litter, mites & mealworms are infected up to 8 weeks. </li></ul><ul><li>Mechanical vector such as wild birds, humans & vermion also transmit disease. </li></ul><ul><li>Litter used as manure spread disease in particular area. </li></ul>
  6. 6. ROUTE OF INFECTION <ul><li>Feco oral route Contaminated feed and water. </li></ul><ul><li>Virus found in high concentration in faeces & litter. </li></ul>
  7. 7. Pathogenesis <ul><li>Pathogenesis Infection </li></ul><ul><li>1- through mouth virus present in macrophages </li></ul><ul><li>2- lymphoid cells in caeca Intestine liver blood viraemia virus goes to bursa </li></ul><ul><li>3- different tissues </li></ul>
  8. 8. PATHOGENESIS <ul><li>Field viruses exhibit different degrees of pathogenicity. White Leghorn exhibit the most sever reaction and has the highest mortality. Less in meat type Period of greatest susceptibility is between 3 to 6 weeks in broilers & 7-12 weeks in layer chicks. Susceptible chicken younger than 3 weeks do not exhibit clinical sign but have sub clinical infection that are economical important because the result can be sever Immunosuppression of the chicken. </li></ul>
  9. 9. Clinical Forms : <ul><li>I. Clinical IBD Birds above 3 weeks of age Temporary Immunosuppression High Mortality </li></ul><ul><li>II. Sub Clinical IBD Birds below 3 weeks of age Permanent Immunosuppression No mortality due to IBD </li></ul>
  10. 10. MORTALITY PATTERN : <ul><li>In broiler Mortality between 3-6 weeks. 2- 5% mortality rarely goes beyond 10%. Peak on 2nd and 3rd day. No mortality on 5th day. </li></ul><ul><li>In layer Mortality between 7-12 weeks of age. 30- 70 % mortality Mortality runs from 7 to 14 days. Two peak. AT 3rd and 4th day AT 7th and 8th day. </li></ul><ul><li>In unvaccinated flock 90% mortality. In cage layer high mortality. </li></ul>
  11. 11. Clinical signs/ symptoms : <ul><li>Depression. </li></ul><ul><li>Inappetance. </li></ul><ul><li>Unsteady gait. </li></ul><ul><li>Huddling under equipment. </li></ul><ul><li>Vent pecking. </li></ul><ul><li>Diarrhoea with urates in mucus </li></ul>
  12. 12. Post-mortem lesions: <ul><li>Bursa of Fabricius - enlarged and haemorrhagic </li></ul>
  13. 13. Post-mortem lesions: <ul><li>Haemorrhages in skeletal muscle (especially on thighs). </li></ul>
  14. 14. Post-mortem lesions <ul><li>Dehydration. </li></ul><ul><li>Swollen kidneys with urates. </li></ul>
  15. 15. Post-mortem lesions <ul><li>Haemorrhagic in the proventriculus -gizzard junction </li></ul>
  16. 16. Diagnosis : <ul><li>Diagnosis History Symptoms Postmortem findings Differential diagnosis from Coccidiosis, Ranikhet, Vitamin A deficiency, fatty liver , Kidney syndrome & hemorrhagic syndrome of muscles. </li></ul><ul><li>Confirmatory diagnosis </li></ul><ul><li>a) ELISA </li></ul><ul><li>b) Isolation & identification of the causal agent. </li></ul>
  17. 17. Treatment : <ul><li>Treatment No specific treatment. Supportive treatment is given to reduce dehydration & improve immunity like electrolytes, Vitamin E, & selenium. </li></ul>
  18. 18. Vaccines : <ul><li>Vaccines Two types of IBD vaccines- </li></ul><ul><li>1) IBD live vaccine </li></ul><ul><li>there are 4 types </li></ul><ul><li>i) Mild vaccine </li></ul><ul><li>ii) Standard intermediate vaccine </li></ul><ul><li>iii) Intermediate plus vaccine </li></ul><ul><li>iv) Hot vaccine </li></ul><ul><li>2) IBD killed vaccine </li></ul>
  19. 19. Vaccination Schedule : <ul><li>Commercial broilers- </li></ul><ul><li>13 day Intermediate plus in drinking water. </li></ul><ul><li>Commercial layers- </li></ul><ul><li>14 & 28 day Standard intermediate plus in drinking water & on 21 day Intermediate plus in drinking water. </li></ul><ul><li>For breeder hen- </li></ul><ul><li>Traditionally at prelay stage & midlay stage IBD inactivated vaccine is given to get high antibody titer. </li></ul>
  20. 20. Resistance : <ul><li>Resistance Birds with maternal antibody are resistant due to high antibody titer. </li></ul><ul><li>When antibody titer drops birds become susceptible. </li></ul><ul><li>Very virulent strain can break the antibody barrier at young age. </li></ul><ul><li>Older birds in which bursa is reduced in size & disappears are more resistant. </li></ul>
  21. 21. Immunity : <ul><li>1) Immunity Active immunity </li></ul><ul><li>a) Natural infection </li></ul><ul><li>b) Vaccination with either live or killed vaccines. </li></ul><ul><li>2) Passive immunity </li></ul><ul><li>a) Antibody transmitted through yolk of the egg. </li></ul><ul><li>b) Passive immunity protects chicks against early infection. </li></ul><ul><li>c) Half life of maternal antibody is between 3 & 5 days thus, if the antibody titer of the progeny is known, the time when chicks will become susceptible can be said </li></ul>
  22. 22. Control : <ul><li>Control Thorough cleaning & disinfection of the houses between the flocks & the practice “all in, all out” management. </li></ul><ul><li>It delays infection & also provide time for vaccines to produce immunity. </li></ul><ul><li>Hygienic & sanitary precautions. Formaldehyde & Iodophores are found to be effective disinfectants. </li></ul><ul><li>Removal of vectors like mealworms & rats. </li></ul><ul><li>Proper vaccination of birds & flocks. </li></ul>