Epidemiology of Marek’s Disease in Commercial Layer Flocks

A cross sectional study was carried out to assess the epidemiological measures of disease occurrence and casual association of Marek’s disease (MD) in 12 different commercial layer flocks. Twenty representative blood and feather tip samples were collected from 12 different MD outbreak flocks. All the samples from each flock were pooled together and subjected to PCR using serotype 1 specific primer (BamH1/BamH2) for confirmation of MD. An epidemiological measures of casual association between MD and identified risk factors such as presence of aflatoxin in feed (> 0.02 ppm), inadequate down time (<12 weeks) and vaccination status were assessed by relative risk and odd’s ratio. Marek’s disease virus (MDV) was detected in feather follicle of nine flocks and four flocks in buffy coat of clinically affected birds by PCR. The morbidity and mortality rates were ranged from 2.01 to 9.15 and 1.03 to 7.6%, respectively. The aflatoxin level in the feed (> 0.02 ppm), type of vaccine and administration of booster dose had positive influence on occurrence of MD compared with inadequate down time.