Vaccines for Marek's disease

Based on comment of burning feathers to reduce spread of MDV may be of any help but in addition the chicken "dander "(chicken dust) epidermal scales frm skin material and feather follicles showed to be a very important factor in the spread/transmission of MDV . The MDV is very stable over long period of time in chicken dander.

Re question of broiler vaccination : in US basically all broilers are vaccinated for MD not only to prevent immunosuppresion but to control Marek's disease condemnation at the processing plant .At all broiler processing plants official USDA inspectors are inspecting birds for condemnation including those caused by MD .(like skin lesions due to MDV)Any bird with MD lesions has to be discarded.

@Senthikumar , yes you are right for the vaccince storage , The Nitrogen level should be above not only for the Bivalent but also for other types of the Marek's disease vaccince etc , other wise it will be useless to do spoiled vaccinations for any types of birds .
The time limit is important not only for the applying the vaccince but also when the vaccince ampule is taken from the Liquid Nitrogen Cannister and while for its prepartions .
Thanks

Thank you for your all comments. I am always opened for the new issues or ideas regarding vaccination against MD. During the last week I isolated a few field strains from broiler chickens vaccinated against Marek's disease with HVT based vaccine. 

HVT in Poland seems to be not enought protection against the disease.
BTW if you would be interested in this subject please take a part in the scheduled conference.
Please check out the link
http://www.avianherpes2012.de/
Hope to see you there.
Greg

Where can I get Marek vaccines?

Double dose or re-vaccination after 6 hours in day old of broiler parents chicks of Marek's vaccine. Which is better? Please give suggestion about this. Is there any problem or side effect using double dose of MD response at day old?

Most of the time it is the missed shots that cause problems. double dose does not prevent slips. 2nd vaccination ensures. Generally, the pfu available in Marek's vaccine are more than prescribed. most important is the brooder house. it the house had earlier incidence and not properly cleaned and rested, the chicks are exposed to field virus which reaches the receptors of the cell surface faster than the vaccine virus.
Bivalent vaccines and dispense stored in liquid nitrogen are more vulnerable for break in cold chain. check the ampoules for break in cold chain. generally, the companies keep the ampoules upside down. if vaccine is found at the narrow end, one should suspect break in cold chain.

Double dose in the same moment or revaccinate the flock after 6 hours, will not give any benefit, but try to give the right dose in the first shoot, more is a little better than less.

Can I see a video of Marek's vaccination done properly?

Very interesting topic.

From our experience here below the main causes of vaccine failure and each one of them is a topic to discuss:

1. Vaccination storage/ handling/ transportation/administration
2. Time of thawing more than 90 sec.
3. Vaccine preparation or handling.
4. Time of vaccine consumption more than 1 hour.
5. Contamination in the vaccination equipment.
6. Poor vaccine administration ex. Non-vaccinated chicks,
7. Shaking the vaccine with the diluent vigorously… etc
8. Age of challenge – in endemic countries first two days of life.
9. Very virulent viruses/ new viruses

I'd witnessed a situation whereby birds started dying when there reached week 10. Me and my team couldn't fathom the real cause of this sudden death. Many tentative and confirmatory tests were carried out, but all gave no particular causal of this death. But with this I read on Dr. Talapanen's wall, could the death of these birds be as result of Marek's prophylaxis failure? Please I need enlightenment

Following are the possible causes of failure of Marek's Disease (MD) Vaccine:-

INCOMPATIBLE VACCINE - Qualitatively i.e. not containing correct type of MD strain. Quantitative i.e. not containing enough PFU. Because MD control is becoming more and more complicated, therefore now higher number of vaccine virus ( 2000- 6000 PFU) needed. Initially in early seventies, only few hundreds of HVT freeze dried vaccine alone was controlling the disease but now even combination of 2 or 3 strains of MD viruses in thousands, some time unable to control the disease.

APPLICATION OF VACCINE - Cell associated vaccines are very delicate and need extra precautions to handle and apply in the hatchery. Some of the writers has already given the details. Maximum number of PFU i.e. more than 3000 from ampule of vaccine should be injected in the day old chicks to get required results.

TRANSPORTATION STRESS - Long distance transportation of chicks is causing stress and reducing the PFU of vaccine virus, therefore extra dose of vaccine usd at day old in hatchery could be helpful to get better protection.
When chick vehicles are passing from highly MD endemic area, contaminated air & dust can infect the chicks inside the vehicle. Mostly it is not possible to avoid this issue but try to select less poultry populated areas for transportation of chicks.

STRICT BIOSECURITY MEASURES OF REARING POULTRY HOUSES - This is the essential part of MD control. Presence of MD field virus in feather follicles,dust etc. of poorly cleaned & disinfected house can infect newly arrived chicks, before the production of immunity in first 2 weeks of age. This become one of the major cause of MD even in very well vaccinated chicks.
Prevention of early exposure is the most important factor to avoid vaccine failure.
Improved hygiene is the cost effective way of reducing the excessive losses of MD in vaccinated flocks.
Dr. M. Akram, Consultant Microbiologist, Micro Lab Karachi.