troubleshooting a marek’s disease outbreakcanadianpoultrymagazine.com/cms_pdfs/marek...chart 1....
TRANSCRIPT
Troubleshooting a Marek’s Disease Outbreak
Enrique Montiel, DVM, MSc., ACPVMerial Avian Global Enterprise
Gainesville, GA©2005 Merial Limited. All rights reserved
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
Marek’s Disease
• The field virus tissue tropism and severity of the lesions may vary
• Causes mortality & condemnations atthe processing plant
• Causes immunosuppression
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
• 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
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
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
Clinical Signs
Marek’s Disease in Broiler Breeders
Marek’s Disease in Broiler BreedersParalysis & depressionParalysis & depression
ParalysisParalysis
Marek’s Disease in Broiler Breeders
ParalysisParalysis
Marek’s Disease in Broiler Breeders
Leg tumors ( Alabama red leg)Leg tumors ( Alabama red leg)
Marek’s Disease in Broiler Breeders
SkinTumorsSkinTumors
Marek’s Disease in Broiler Breeders
Spleen TumorsSpleen Tumors
Marek’s Disease in Broiler Breeders
Intestinal TumorsIntestinal Tumors
Marek’s Disease in Broiler Breeders
Marek’s Disease in Broilers
Leg tumors ( Alabama red leg)Leg tumors ( Alabama red leg)
Marek’s Disease in Broilers
Leg tumorsLeg tumors
Marek’s Disease in Broilers
Skin TumorsSkin Tumors
Marek’s Disease in Broilers
Liver TumorsLiver Tumors
Marek’s Disease in Broilers
Liver Tumors with necrotic centersLiver Tumors with necrotic centers
Marek’s Disease in Broilers
Control BursaControl Bursa MDV-Infected bursaMDV-Infected bursa
Marek’s Disease in Broilers
Marek’s Disease in Commercial Layers
Liver Tumors in LayersLiver Tumors in Layers
Marek’s Disease in Commercial Layers
Marek’s DiseaseThe only known methods of preventing Marek’s Disease are:
•Vaccination•Good flock management•Cleaning, disinfection and biosecurity
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
•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
•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
•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
Interval
Vaccination-Challenge
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
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
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
• 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
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
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.
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
Preparation for
Vaccine Mixing
Mix vaccine in a clean, low-traffic area.
Frozen Vaccine Storage
Keep Frozen Vaccines Properly Identified.
Liquid Nitrogen Safety
ProtectiveClothing Required
Routinely monitor the level of liquid nitrogen in the tank.
Vaccine Handling
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.
Quality Assurance Indicator
(Product in the frozen state)
Acceptable Acceptable Unacceptable
Store Diluent at Room Temperature
Examine Each Bag for Contamination.
Examine Each Bag for Contamination.
Good diluentGood diluent ContaminatedContaminated
Fill thaw-bath with distilled
water.
Do not add bleach or sanitizer.
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)
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
Mixing the Vaccine
Always mix the vaccine following the instructions on the vaccine
insert
Clean and Prepare the Working Area
Wash hands thoroughly before mixing.
Use hand sanitizers
Adding Antibiotics
• Vaccines are not licensed for combination with these products.
• Some antibiotics can significantly reduce the Marek’s vaccine titer
Calculating the Number of Ampules Needed
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
Thaw ampules by gently
swirling the ampules in the
thaw-bath.
Never Leave Ampules Unattended
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.
Use paper towels to dry hands and ampules.
Cloth towels can become contaminated.
Merial’s Ampule Breaker
Steps in Vaccine Mixing
1*1*22 33
44 5555 66
1* dye added 5 minutes prior vaccine mixing
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
By rinsing the ampules & ampule tips, additional virus
can be recovered.
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
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
Mix the bag gently to distribute the vaccine evenly.
The prepared vaccine should be
used within 1 to 2 hours from
the time of preparation.
Place the bag on ice for
transport to the in ovo machine
An ice pack should be used to keep the vaccine cool.
Proper disposal of biohazard material is
critical.
An alternate mixer should be trained and allowed to mix the vaccine at least
once a week.
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
Vaccine Administration
Subcutaneous vaccination at one day of ageSubcutaneous vaccination at one day of age
Subcutaneous vaccination at one day of ageSubcutaneous vaccination at one day of age
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
In ovo Injection
Proper Procedures forin ovo Vaccination
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
Prepare fresh sanitizing solutions daily.
Loading the Eggs
Run The Check Plate After Each Buggy to Make Sure There
Are No Plugged Needles
Check Eggs For Contamination
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
Summary (cntd.)
– Vaccination programs tailored to the type of bird and field situation
– Good vaccine preparation and administration practices
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.
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.
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.