It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Leaky Vaccines Enhance Spread of Deadlier Chicken Viruses
The Marek’s vaccine is “imperfect” or “leaky.”
That is, it protects chickens from developing disease, but doesn’t stop them from becoming infected or from spreading the virus.
Inadvertently, this made it easier for the most virulent strains to survive.
Within ten years, it [Marek's] started evolving into more virulent strains, which now trigger more severe cancers and afflict chickens at earlier ages.
This chicken vaccine makes its virus more dangerous
In fact, rather than stop fowl from spreading the virus, the vaccine allows the disease to spread faster and longer than it normally would, a new study finds. The scientists now believe that this vaccine has helped this chicken virus become uniquely virulent.
originally posted by: IAMTAT
What the article say?
Researchers from the US Department of Agriculture’s Avian Disease and Oncology Laboratory (ADOL) and the Roslin Institute, Scotland, tested the impact of vaccination on Marek’s disease transmission. One group of birds received a leaky vaccine – this contained a related live virus originating from turkeys, which causes an immune response but no symptoms. A second group was given a sham vaccine, which contained no biological material. Both groups were then infected with Marek’s disease virus.
Groups of infected birds were placed with sets of unvaccinated chickens and more than 97% of the birds became infected. However, unvaccinated chickens that had contact with vaccinated birds were less likely to develop full-blown Marek’s disease and there were also fewer deaths. This was found to be because vaccinated birds transmitted fewer copies of Marek’s disease virus.
originally posted by: nonspecific
It got rather interesting a few years later.
a reply to: IAMTAT
I know that vaccinated chickens are very contagious and will easily infect and most likely kill unvaccinated chickens though.