Leaky vaccines help prevent transmission of Marek’s disease

Imperfect vaccines – ones that manage disease symptoms but fail to prevent infection and spread – can protect chickens against the painful symptoms of Marek’s disease, finds a new study from the Roslin Institute at the University of Edinburgh and the U.S. Department of Agriculture’s Avian Disease and Oncology Laboratory (ADOL).

Doughman Headshot3 Headshot
(David Tadevosian)
(David Tadevosian)

Imperfect vaccines – ones that manage disease symptoms but fail to prevent infection and spread – can protect chickens against the painful symptoms of Marek’s disease, finds a new study from the Roslin Institute at the University of Edinburgh and the U.S. Department of Agriculture’s Avian Disease and Oncology Laboratory (ADOL).

Unvaccinated chickens in the same flock as vaccinated birds also benefited.

“Normally, we expect that vaccination just protects the vaccinated animal, but we found that vaccination also protects the animals that become infected and come in contact with vaccinated animals,” Andrea Doeschl-Wilson, Personal Chair in Animal Disease Genetics and Modeling at the Roslin Institute, explained.

Marek’s disease

Marek’s disease is a highly contagious viral disease that can cause tumors to develop in various parts of the body, eye cancer, wing and leg paralysis and eventually death. It is spread through bird feed, bedding material, bird droppings, feathers and dead skin. The disease costs the poultry industry an estimated $1 billion each year.

Leaky vaccines are the most commonly used treatment for Marek’s disease. These therapeutics protect chickens against the virus, researchers believed they did little to prevent infection or stop the spread to flock mates.

The study

The researchers gave a leaky vaccine containing a related live virus to a group of chickens and then infected them with Marek’s disease. The control group received a sham vaccine.

The birds were placed into flocks with unvaccinated chickens. More than 97% of the birds became infected. However, the unvaccinated chickens that were in contact with vaccinated birds were less likely to develop to develop the painful symptoms associated with the virus and more likely to survive.

“Quite often, you can’t vaccinate the entire population. This study implies that it’s okay if only a proportion of animals are vaccinated because even the non-vaccinated ones are protected,” Doeschl-Wilson said.

Like what you just read? Sign up now for free to receive the Poultry Future Newsletter

Page 1 of 178
Next Page