Poultry disease #1

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dmandrus
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307592
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Poultry disease #1
Updated:
2015-09-09 21:53:52
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Poultry disease
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Poultry disease #1
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  1. Mereks disease is seen in what species mostly? What other species are susceptible?
    • Chickens
    • Quail, turkey, pheasents
  2. What causes mereks disease
    Herpesvirus
  3. What age group of chickens is mereks common in?
    2-7 months but anything over 3 weeks
  4. What are the 3 serotypes of mereks disease and which one is most important
    • Gallid herpesvirus 2 - oncogenic and virulent
    • Gallid herpesvirus 3
    • meleagrid herpesvirus 1
  5. How is mereks transfered
    Virus replicates in the epithelial cells of the feather follicle. INfected chcikens shed virus indefinietly
  6. Does mereks transfer vertically
    No
  7. What are the 2 main signs of mereks disease
    • Paralysis
    • Neoplasms
  8. 2 forms of mereks?
    • Classical form - ataxia, flaccid paralysis, neoplasms
    • acute form - death within 24-72hr following onset of paralytic signs
  9. 3 gross pathological changes seen in the nerves of mereks affected birds?
    • Loss of cross striations
    • gray or yellow discoloration
    • nerve tract enlargement
  10. Where do mereks birds typically develope neoplasia
    • Visceral organs
    • ovary, lungs, heart, kidney, liver, intestins, iris
  11. 4 pathological lesions seen on necropsy of mereks birds
    • 3 nerve lesions
    • Visceral tumors
    • enlargment of feather follicles
    • discoloration of the iris
  12. What do we see on the skin of mereks birds?
    Enlarged feather follicles
  13. What do we see on histopathology of mereks birds?
    • Pleomorphic lymphocytes
    • mainly t cells but some b cells
  14. 4 points to getting a mereks diagnoses
    • History
    • age of birds
    • location of neoplastic lesion
    • histopathology
  15. What serotypes do we vaccinate against mereks with?
    2 and 3
  16. 3 ways to control mereks?
    • Vaccination
    • genetic resistance
    • biosecurity
  17. 2 WAYS TO VACCINATE FOR MEREKS?
    • Sub Q
    • In ovo vaccination
  18. HAs the virus changed over time?
    Yes the lesions and clinical presentations have greatly changed
  19. What is the mortality of a flock that is vaccinated and gets mareks
    • Layers <5%
    • Broilers 0.1-0.5%
  20. Do non oncogenic strains of mereks protect against the oncogenic?
    Quite well
  21. What kind of virus is avian leukosis/sarcoma virus
    Retrovirus
  22. When do we see leukosis virus?
    Semimature/mature chickens
  23. Leukosis virus shows what pattern of neoplastic emergence?
    Persistantly low mortality with neoplasia in the bursa, liver, and other visceral organs
  24. Differentiate the kind of cancer that we see with mereks and with leukosis virus
    Mereks is always a lymphocytic line of neoplasia and leukosis can be lymphoid, erythroid, or myeloid
  25. What are 3 lines of leukosis virus
    • Lymphoid
    • Erythroid
    • Myeloid
  26. Mortality with leukosis?
    1-2% but could be up to 20%
  27. Leukosis virus does not occur prior to?
    14 bweeks of age
  28. How is leukosis virus transmitted primarily?
    Vertically for the most part. Only exogenous virus is important in maintain the infection not endogenous
  29. Why is endogenous virus not important to infection
    avirulent and genetically defective
  30. See marked pages in handout #1 for important diagrams
  31. Horizontal transmission of leukosis only occurs when?
    WHen birds are very young
  32. Are all birds with virus and carrying virus ab+?
    No many are negative
  33. 3 major clinical signs of leukosis?
    • Enlargment of abdomen
    • Enlarged and lumpy bursa of fabricius
    • Depressed egg production
  34. How can you control avian leukosis?
    Eradication
  35. As soon as mass neoplasisa is not of leukosis origin it is cause by?
    Leukosis virus
  36. 2 hints microscopically that it is leukosis virus?
    • Uniformly lymphoblastic
    • B cells have surface IgM markers
    • Where as T cells in mereks lack IgM markers
  37. 3 parts of leukosis diagnosis
    • Age of affected chickens
    • Pattern of mortality
    • Bursal lesions
  38. 2 forms of erythroblastosis with avian leukosis
    • Proliferative form -liver, spleen etc enlargement
    • Anemic form
  39. What do we see with myeloblastosis leukosis
    Liver is greatly enlatrged
  40. Who is more susceptible to myeloid leukosis?
    Meat type birds
  41. What subgroup of leukosis causes myeloid leukosis (myelocytic myeloid leukosis)?
    ALV - J
  42. What are the clinical signs of myelocytomatosis
    Skeletal myelocytomas
  43. Leukosis comes from where on the production chain
  44. Top of pyramid
  45. How does leukosis cause osteopetrosis
    Virus interferes with growth and differentiation fo osteoblasts, sweeling the diaphyses of nlong bones
  46. Do birds develop active immunity against ALV?
    Yes as long as they are older. If infected at a young age they will likely be permanently viremic. if older they will likely become tolerant to infection
  47. The birds body uses what type of immunity to protect against ALV?
    Cell mediated immunity.
  48. Is the a ALV vaccine?
    NO
  49. What is the only way to control ALV?
    Why do you have to test multiple ways to know if an animal is postive
    • Eradication
    • Due to endogenous virus that does not produce disease, and antibodies cannot be trusted
  50. 4 parts to ALV eradication
    • Negative egg albumin or vaginal swab test
    • Hatching of chicks in isloation in small groups
    • Avoid manual vent sxing and vaccination with common needle
    • Cleaning and disinfection of incubators brooding houses and all equipment
  51. If you see endemic fibrosarcomas you know you have a what infection?
    ALV

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