Retrospective Studies of Marek’s Disease Diagnosed in Some Towns in Nigeria, 2000 - 2009

Studies on the prevalence of Marekʹs disease (MD) from veterinary clinics across Nigeria between 2000 and 2009 were investigated based on available poultry disease records. Of the 1,970 poultry viral diseases recorded, 1,193 (60.6%) were diagnosed for Marek’s disease. The mean age of birds diagnosed with MD included were, 319 broilers (7.8 weeks), 77 cockerels (15.0 weeks), 952 pullets (12.9 weeks), and 602 layers (29.9 weeks). The prevalence of MD was significantly higher (p < 0.05) among poultry aged 18 weeks and above (85.5%) compared to those aged 9 – 17 weeks (71.4%) and 5 - 8 weeks (25.3%), but least among 1-4 weeks (14.7%). Layers and pullets had higher prevalence of MD 86.7% and 62.1% respectively. The risk factors for MD using odds ratio association on age, type, region of the country, showed statistically significant associations; poultry aged 18 weeks and above were 34.3 times more likely at risk of having Marek’s disease compared to chicks aged 1 – 5 weeks. Compared to broiler, layer had the highest odds ratio of coming down with Marek’s disease (OR 31.3), followed by pullets (OR 7.9) and turkeys (OR 3.2). The probabilities of birds coming down with MD were significantly higher in the southern (OR 7.8) compared to northern part of Nigeria and slightly higher during the rainy season (OR 1.4) compared to dry season. The probability decreased in 2006 and 2007 (OR 0.7) but increased in 2008 and 2009 (OR 1.5 and 2.0 respectively). The importance of diagnostic surveillance of MD was discussed.