troubleshooting a marek’s disease outbreakcanadianpoultrymagazine.com/cms_pdfs/marek...chart 1....
TRANSCRIPT
![Page 1: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/1.jpg)
Troubleshooting a Marek’s Disease Outbreak
Enrique Montiel, DVM, MSc., ACPVMerial Avian Global Enterprise
Gainesville, GA©2005 Merial Limited. All rights reserved
![Page 2: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/2.jpg)
Marek’s Disease
•Marek’s Disease was first reported in 1917 by Dr. Jozsef Marek in Budapest, Hungary
•Three serotypes described
•Causes malignant tumorsin the chicken’s skin and internal organs
![Page 3: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/3.jpg)
Marek’s Disease
• The field virus tissue tropism and severity of the lesions may vary
• Causes mortality & condemnations atthe processing plant
• Causes immunosuppression
![Page 4: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/4.jpg)
Marek’s Disease Virus Serotypes
Low Pathogenicitystrains- CVI988 (Rispens)- Clone C- CR-6
HVTSB1
301B
Oncogenic strains- GA- MD11- MD5- TK - RB1B- etc.
Serotype 3Serotype 2Serotype 1
![Page 5: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/5.jpg)
• The virus replicates to the fully infectious form in the feather follicles
• The route of infection is the respiratory system by inhaling infectious viral particles
• Tumors (lesions) occur due to the malignant transformation of the lymphocytes
Marek’s Disease
![Page 6: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/6.jpg)
Marek’s Disease
• The first wave of virus infection targets the bursa and thymus
• The infection may produce immunosuppression in a transient or permanent form
• The disease may show various clinical signs
![Page 7: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/7.jpg)
Marek’s Disease•Very virulent strains (vvMDV+) have been reported in a number of countries around the world and have affected broilers, breeders and commercial layers
•Great economic impact
•Marek’s can be prevented by implementing a vaccination program
![Page 8: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/8.jpg)
Clinical Signs
![Page 9: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/9.jpg)
Marek’s Disease in Broiler Breeders
![Page 10: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/10.jpg)
Marek’s Disease in Broiler BreedersParalysis & depressionParalysis & depression
![Page 11: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/11.jpg)
ParalysisParalysis
Marek’s Disease in Broiler Breeders
![Page 12: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/12.jpg)
ParalysisParalysis
Marek’s Disease in Broiler Breeders
![Page 13: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/13.jpg)
Leg tumors ( Alabama red leg)Leg tumors ( Alabama red leg)
Marek’s Disease in Broiler Breeders
![Page 14: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/14.jpg)
SkinTumorsSkinTumors
Marek’s Disease in Broiler Breeders
![Page 15: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/15.jpg)
Spleen TumorsSpleen Tumors
Marek’s Disease in Broiler Breeders
![Page 16: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/16.jpg)
Intestinal TumorsIntestinal Tumors
Marek’s Disease in Broiler Breeders
![Page 17: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/17.jpg)
Marek’s Disease in Broilers
![Page 18: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/18.jpg)
Leg tumors ( Alabama red leg)Leg tumors ( Alabama red leg)
Marek’s Disease in Broilers
![Page 19: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/19.jpg)
Leg tumorsLeg tumors
Marek’s Disease in Broilers
![Page 20: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/20.jpg)
Skin TumorsSkin Tumors
Marek’s Disease in Broilers
![Page 21: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/21.jpg)
Liver TumorsLiver Tumors
Marek’s Disease in Broilers
![Page 22: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/22.jpg)
Liver Tumors with necrotic centersLiver Tumors with necrotic centers
Marek’s Disease in Broilers
![Page 23: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/23.jpg)
Control BursaControl Bursa MDV-Infected bursaMDV-Infected bursa
Marek’s Disease in Broilers
![Page 24: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/24.jpg)
Marek’s Disease in Commercial Layers
![Page 25: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/25.jpg)
Liver Tumors in LayersLiver Tumors in Layers
Marek’s Disease in Commercial Layers
![Page 26: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/26.jpg)
Marek’s DiseaseThe only known methods of preventing Marek’s Disease are:
•Vaccination•Good flock management•Cleaning, disinfection and biosecurity
![Page 27: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/27.jpg)
Marek’s Vaccination FailureMD outbreaks may appear in vaccinated flocks because:
•High field challenge by very virulent Marek’s disease virus strains (vvMDV or vvMDV+) •Interval vaccination – Challenge•Presence of immunosuppressive agents•Inadequate vaccination programs•Poor vaccine preparation and administration
![Page 28: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/28.jpg)
•High Field challenge by Very Virulent Marek’s Disease Virus (vvMDV or vvMDV+) Strains
- If the field challenge is too high, it can overcome the vaccine immunity and produce an outbreak even in older birds
- Previous reports indicate the incidence of Marek’s outbreak in layers and broiler breeders over 40 weeks of age
Marek’s Vaccination Failure
![Page 29: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/29.jpg)
•The Presence of other immunosuppressive agents may interfere with the development of protection against Marek’s disease
•Infectious Bursal Disease Virus (IBDV)•Chicken Anemia Virus (CIAV)•Avian Leukosis subtype J•Mycotoxins
Marek’s Vaccination Failure
![Page 30: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/30.jpg)
•Interval Vaccination – Challenge
•Good cleaning and disinfection should delay the exposure of baby chicks to field challenge
•This delay of the exposure will allow the proper development of vaccine-provided protection
•Day old chicks should be placed in an environment as clean as possible
Marek’s Vaccination Failure
![Page 31: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/31.jpg)
Interval
Vaccination-Challenge
![Page 32: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/32.jpg)
Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge With
MDV T.K. (Respiratory Route Using a Shedder System) at One Day of Age or When 5 Days Old
010203040
CVI988-A CVI988-A +HVT
CVI988-A +HVT+SB1
HVT+SB1
Vaccines
Perc
ent A
ffect
ed
1 Day Old5 days of age
Montiel, 1995Montiel, 1995
![Page 33: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/33.jpg)
Marek’s Vaccination Failure
•Inadequate Vaccination Programs
•Vaccination programs must be designed according to the type of bird and field challenge
•Re-vaccination may be considered under high challenge conditions
![Page 34: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/34.jpg)
Most commonly Used MD Vaccination Programs
Rispens & Combinations
HVT+SB1
HVT
Broilers
HVT+SB1
HVT+Rispens+SB1
HVT+Rispens
Layers
HVT+SB1
Rispens
HVT+Rispens
BroilerBreeders
3
2
1
Program
![Page 35: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/35.jpg)
• The best program in meat-type birds is the HVT+Rispens combination
• More recent publications suggest that the best program for commercial layers is the HVT+Rispens+SB1 combination
Commonly Used MD Vaccination Programs
![Page 36: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/36.jpg)
70 80 90 100
Vac
cine
s
Rispens 2+HVTRispens 1+HVTRispens+HVT+SB1
Percent Protection in Commercial Female Broilers Challenged with the MDV TK Isolate* by intra-abdominal injection 5 days post vaccination
*Challenge dose: 1:100 dilution of TK seedstockPercent ProtectionPercent ProtectionPercent Protection
![Page 37: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/37.jpg)
Marek’s Vaccination Failure
•Vaccine preparation and administration
•Must follow the manufacturer’s instructions
•Improper vaccine preparation and administration techniques may seriously compromise the vaccine titer.
![Page 38: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/38.jpg)
Marek’s Vaccination Failure
•Improvement in vaccine preparation and administration has contributed to the decrease in the incidence of Marek’s disease in a number of operations around the world
![Page 39: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/39.jpg)
Preparation for
Vaccine Mixing
![Page 40: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/40.jpg)
Mix vaccine in a clean, low-traffic area.
![Page 41: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/41.jpg)
Frozen Vaccine Storage
![Page 42: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/42.jpg)
Keep Frozen Vaccines Properly Identified.
![Page 43: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/43.jpg)
Liquid Nitrogen Safety
ProtectiveClothing Required
![Page 44: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/44.jpg)
Routinely monitor the level of liquid nitrogen in the tank.
![Page 45: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/45.jpg)
Vaccine Handling
![Page 46: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/46.jpg)
Check Frozen Vaccines Ampules
• Marek’s vaccines ampules may be stored inverted in the liquid nitrogen tank. When checking ampules, make sure you follow the quality assurance indicator before thawing.
![Page 47: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/47.jpg)
Quality Assurance Indicator
(Product in the frozen state)
Acceptable Acceptable Unacceptable
![Page 48: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/48.jpg)
Store Diluent at Room Temperature
![Page 49: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/49.jpg)
Examine Each Bag for Contamination.
![Page 50: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/50.jpg)
Examine Each Bag for Contamination.
Good diluentGood diluent ContaminatedContaminated
![Page 51: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/51.jpg)
Fill thaw-bath with distilled
water.
Do not add bleach or sanitizer.
![Page 52: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/52.jpg)
Most Hatcheries keep thaw-bath at 80 °F
(27 ° C).
Thaw no more than what is needed for
immediate use.
Ampules may be
thawed in water
At 27-37 °C
(80- 98.6 F)
Ampules may be
thawed in water
At 27-37 °C
(80- 98.6 F)
![Page 53: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/53.jpg)
Preparation Checklist• Mixing Room
• clean, low traffic
• Liquid Nitrogen • safety considerations, adequate levels of liquid
nitrogen, no Newcastle contamination
• Diluent• room temperature, no contamination
• Thaw-bath• Fresh distilled water, 80 – 96 °F
![Page 54: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/54.jpg)
Mixing the Vaccine
![Page 55: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/55.jpg)
Always mix the vaccine following the instructions on the vaccine
insert
![Page 56: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/56.jpg)
Clean and Prepare the Working Area
![Page 57: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/57.jpg)
Wash hands thoroughly before mixing.
Use hand sanitizers
![Page 58: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/58.jpg)
Adding Antibiotics
• Vaccines are not licensed for combination with these products.
• Some antibiotics can significantly reduce the Marek’s vaccine titer
![Page 59: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/59.jpg)
Calculating the Number of Ampules Needed
![Page 60: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/60.jpg)
Determining the Number of Ampules Needed
0.05 ml/egg
1200 ml bag ÷ 0.05 ml per chick = 24,000 eggs per bag
1 ampule = 2000 doses (check ampule)
At full dose, you would need 12 ampules (24,000 ÷ 2000) of the 2000 dose vaccine or 6
ampules of the 4000 dose vaccine
![Page 61: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/61.jpg)
Thaw ampules by gently
swirling the ampules in the
thaw-bath.
![Page 62: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/62.jpg)
Never Leave Ampules Unattended
![Page 63: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/63.jpg)
Once an ampule has thawed, never refreeze the ampule
Ampules that have been thawed and re-frozen can lose up to 97% of its PFU.
![Page 64: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/64.jpg)
Use paper towels to dry hands and ampules.
Cloth towels can become contaminated.
![Page 65: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/65.jpg)
Merial’s Ampule Breaker
![Page 66: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/66.jpg)
Steps in Vaccine Mixing
1*1*22 33
44 5555 66
1* dye added 5 minutes prior vaccine mixing
![Page 67: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/67.jpg)
1. Disinfect the port of diluent bag2. Take some diluent in a sterile syringe3. Extract vaccine from ampule with the
diluent-filled syringe4. Gently inject the vaccine into the
diluent bag5. Take some diluent into the syringe
again and rinse the ampule6. Mix the bag gently to distribute the
vaccine evenly
Steps in Vaccine Mixing
![Page 68: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/68.jpg)
By rinsing the ampules & ampule tips, additional virus
can be recovered.
![Page 69: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/69.jpg)
Marek's Vaccine Titer Percent Difference in rinsed ampoules compared with a non-rinsed
control
-6% ---+12.8
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
None Ampule only Ampule +cap
Tit
er
![Page 70: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/70.jpg)
Complete Process From Point A to Point B as Soon
as Possible
Point A
Take vaccine out of liquid nitrogen tank
Point B
Inject the vaccine in the diluent bag
![Page 71: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/71.jpg)
Mix the bag gently to distribute the vaccine evenly.
![Page 72: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/72.jpg)
The prepared vaccine should be
used within 1 to 2 hours from
the time of preparation.
![Page 73: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/73.jpg)
Place the bag on ice for
transport to the in ovo machine
![Page 74: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/74.jpg)
An ice pack should be used to keep the vaccine cool.
![Page 75: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/75.jpg)
Proper disposal of biohazard material is
critical.
![Page 76: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/76.jpg)
An alternate mixer should be trained and allowed to mix the vaccine at least
once a week.
![Page 77: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/77.jpg)
Vaccine Mixing Checklist
• Hands washed, mixing area cleaned
• Dye or antibiotic added more than 5 minutes before vaccine
• Number of ampules per bag calculated properly
• Vaccine thawed properly
• Hands and ampules dried before opening the ampule
• Vaccine carefully added to bag
• Ampules and tips rinsed
• Bag gently squeezed to evenly mix the vaccine
• Alternate mixer evaluated
![Page 78: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/78.jpg)
Vaccine Administration
![Page 79: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/79.jpg)
Subcutaneous vaccination at one day of ageSubcutaneous vaccination at one day of age
![Page 80: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/80.jpg)
Subcutaneous vaccination at one day of ageSubcutaneous vaccination at one day of age
![Page 81: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/81.jpg)
Inspecting Subcutaneous Vaccination
• Conduct routine random checking of vaccinated chicks
• The minimum level of accuracy (properly vaccinated chicks) must be at least 97%
• If less than 97% accurate, the procedures need to be reviewed to detect where the problem is and implement correctives
![Page 82: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/82.jpg)
In ovo Injection
![Page 83: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/83.jpg)
Proper Procedures forin ovo Vaccination
![Page 84: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/84.jpg)
Proper maintenance and QC is critical for in ovo vaccination.
Always adhere to scheduled maintenance of your vaccination equipment.
Proper equipment sterilization and cleaning is critical.
Properly maintained equipment will always be more dependable
Quality Control Manual
![Page 85: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/85.jpg)
Prepare fresh sanitizing solutions daily.
![Page 86: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/86.jpg)
Loading the Eggs
![Page 87: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/87.jpg)
Run The Check Plate After Each Buggy to Make Sure There
Are No Plugged Needles
![Page 88: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/88.jpg)
Check Eggs For Contamination
![Page 89: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/89.jpg)
Summary
• Vaccination, in conjunction with the following initiatives, will greatly reduce the incidence of Marek's disease in the field:
– Good farm cleaning and disinfection – Proper reception practices– Adequate downtime between flocks– Accurate vaccination program
![Page 90: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/90.jpg)
Summary (cntd.)
– Vaccination programs tailored to the type of bird and field situation
– Good vaccine preparation and administration practices
![Page 91: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/91.jpg)
ReferencesBatra, P., A.K. Pruthi and J.R. Sadana. 1991. Effect of aflatoxin B1 on the efficacy
of turkey herpesvirus vaccine against Marek's disease. Avian Pathol. 51(1):115-119.
Calnek BW, Harris RW, Buscaglia C, Schat KA, Lucio B. 1998. Relationship between the immunosuppressive potential and the pathotype of Marek's disease virus isolates. Avian Dis. 1998 Jan-Mar;42(1):124-32.
Calnek, B.W. 1985b. Pathogenesis of Marek's Disease. A review. In B.W. Calnekand J.L. Spencer (eds). Proc. Int. Symp. Marek's Dis. pp. 374-390. Am. Assoc. Avian Pathol. Kennett Square, PA.
Calnek, B.W. 1985a. Genetic Resistance. In L.N. Payne (ed) Marek's Disease, pp 293-328. Martinus Nijhoff. Boston.
Cloud S.S., H. Lillehoj and J.K. Rosenberger. 1992. Immune Disfunction Following Infection with Chicken Anemia Agent and Infectious Bursal Disease Virus I. Kinetic Alterations of Avian Lymphocyte Subpopulations. Vet. Immunol. Immunopatho. 34:337-352. 1992.
Ficken, M.D., M.P. Nasisse, G.D. Boggan, J.S. Guy, D.P. Wages, R.L. Witter, J.K. Rosenberger and R.M. Nordgren. 1991. Marek's Disease Virus Isolates With Unusual Tropism and Virulence for Ocular Tissues: Clinical Findings, Challenge Studies and Pathological Features. Avian Pathol. 20:461-474.
![Page 92: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/92.jpg)
ReferencesGimeno IM, Witter RL, Hunt HD, Reddy SM, Reed WM.2004. Biocharacteristics
shared by highly protective vaccines against Marek's disease. Avian Pathol. 2004 Feb;33(1):59-68
Gimeno IM, Witter RL, Reed WM. 1999. Four distinct neurologic syndromes in Marek's disease: effect of viral strain and pathotype. Avian Dis. 1999 Oct-Dec;43(4):721-37
Montiel, E. 1995. Master Thesis, Depart. of Animal Science & Agric. Biochem., University of Delaware, Newark, DE 19717-1303.
Montiel, E.R., J.K. Rosenberger and S.S. Cloud. 1994. The efficacy of available andexperimental vaccines for inducing protection against challenge with a potativevariant Marek's disease virus. Proc. 66th Northeastern Conf. on Avian Dis. pp. 34.
Otaki, Y., T. Nunoya, M. Tajima, A. Kato, Y. Nomura. 1988. Depression of vaccinalimmunity to Marek's disease by infection with chicken anemia agent. AvianPathol. 17:333-347.
Payne, L.N. 1972. Pathogenesis of Marek's disease - a review. In P.M. Biggs, G de Thé, and L.N. Payne (eds). Oncogenesis and Herpesviruses, pp. 21-37. IARC, Lyons, France.
Rosenberger J.K., S.S. Cloud, D. Anderson, E. Montiel and Y. Velasquez. 1993. Marek's Disease in Delmarva Broilers. Proc. 28th Natl. Meet. on Poultry Healthand Condemn. Ocean City Maryland pp. 70.
![Page 93: Troubleshooting a Marek’s Disease Outbreakcanadianpoultrymagazine.com/cms_pdfs/Marek...Chart 1. Percent Total Affected (Lesions Plus Mortality) 2 Through 8 Weeks After Challenge](https://reader031.vdocuments.net/reader031/viewer/2022030415/5aa14bd17f8b9ada698b6c96/html5/thumbnails/93.jpg)
ReferencesWitter, R.L. 1987. New serotype 2 and attenuated serotype 1 Marek's disease
vaccine viruses: comparative efficacy. Avian Dis. 31:752-765.Witter, R.L. 1992. Safety and comparative efficacy of the CV1988/Rispens vaccine
strain. Proc. XIX World's Poult. Congress. Amsterdam, the Netherlands, p 315-319.
Witter, R.L. 1993. Evolution of Virulence Among Marek's Disease Virus Strains: Implications for Control. Proc. 65th Northeastern Conf.on Avian Dis. pp 6.
Witter RL, Gimeno IM, Reed WM, Bacon LD. 1999. An acute form of transient paralysis induced by highly virulent strains of Marek's disease virus. Avian Dis. 1999 Oct-Dec;43(4):704-20.