We report the presence of Marek’s disease (MD) virus meq among commercial layer chickens with or without the history of MD outbreak. Feather follicle epithelial (FFE) samples (285) were collected from 50 vaccinated commercial layer flocks of Tamil Nadu in India regardless of MD outbreak and were subjected to polymerase chain reaction (PCR) to amplify MDV specific meq gene. The prevalence of MD was found to be 50 per cent. Among 285 feather follicle samples tested from different age groups, the highest prevalence was noticed at 17 to 40 week age groups (38.03 per cent) followed by 9 to 16 week age groups (33.33 per cent), 41 to 60 week (32.26 per cent) age groups, 61 week and above (32.14 per cent) age groups and 0 to 8 week (23.68 per cent) age groups with overall prevalence of 32.63 per cent. The highest prevalence was noticed in the peak production period which might be attributed to activation of latent virus. It is suggested that the MD prevalence in twice vaccinated layer flocks warrants for stringent control measures in order to check the re-emergence of MD among layer chicken.

Highlights

• Marek’s disease prevalence was detected in the vaccinated commercial layer chicken.
• Feather follicle epithelium samples were used to amplify MDV meq gene by PCR.
• The highest prevalence was recorded in the peak egg production group.