- Mixing vaccinated birds with non-vaccinated birds will put those individuals who have not received the vaccine at risk, since the vaccine does not prevent infection or shedding of the virulent virus in birds, it only prevents clinical signs of disease.
- Breed – Leghorns and light egg-type breeds are more vulnerable to disease than heavier breeds. Silkies, Sebrights, and Polish breeds are highly susceptible to Marek’s disease.
- Brooding chicks under 6 months of age in the same environment as adult flock members
- Co-infection with immunodepressive pathogens such as chicken anemia virus
- Chickens with poor immune systems
Red the Rooster with Marek’s
- Gastrointestinal obstruction
- Lead poisoning
- Lymphoid leukosis
- Newcastle disease
- Pendulous crop
- Renal tumors
- One leg stretched forward and the other back
- Paralysis of the legs, wings, or neck
- Delayed crop emptying
- Partial on complete blindness
- Irregular-shaped or unequally sized pupils
- Change in eye color (to gray)
- Enlarged feather follicles
- Reddened legs
- Loss in appetite
- Weight loss
- Clinical signs
- Physical exam
- Complete Blood Count (CBC) and Biochemistry – monitored for changes in health status.
- Histopathological exam of affected organs, including peripheral nerves.
- Reduce stress
- Vaccinate chicks – Administer MDV vaccine to chicks shortly after they hatch. It is given subcutaneously (under the skin) at the back of the neck. Chicks require 7 to 14 days in order to become immunized against MDV.
- Newly hatched chicks should not be put in the same environment as older flock members until they are at least 6 months old.
Ocular (eye) form: Lymphoid infiltration into eyes; causes change in iris color, pupil shape or size, partial or total blindness. Rare, occurs usually in older birds; mortality up to 25%.
Cutaneous (skin) form: Lymphoid infiltration into skin; causes enlarged feather follicles, often scattered or clustered together, especially on the legs. Occurs commonly; 0% morality rate.
- Yang, Fan et al.. Antiviral effect of baicalin on Marek’s disease virus in CEF cells BMC veterinary research vol. 16,1 (2020)
- Shi, Meng-Ya et al.. The Emergence of a vv + MDV Can Break through the Protections Provided by the Current Vaccines Viruses vol. 12,9 (2020)
- Bailey, Richard I., et al.. Pathogen transmission from vaccinated hosts can cause dose-dependent reduction in virulence PLoS biology 18.3 (2020) Bertzbach, Luca D., et al. Latest Insights into Marek’s Disease Virus Pathogenesis and Tumorigenesis Cancers 12.3 (2020)
- Yu, Zhenghao, et al.. Natural co-infection with two virulent wild strains of Marek’s disease virus in a commercial layer flock Veterinary Microbiology 240 (2020)
- R Hauck et al. Two Cases of Marek’s Disease in Backyard Turkeys Avian diseases (2020)