A TEN YEAR PREVALENCE STUDY OF MAREK'S DISEASE AND AVIAN LEUKOSES AT IBADAN, NIGERIA

Fatunmbi 0.0., D. F. Adene: A Ten year Prevalence Study of Marek's Disease and Avian Leukoses at Ibadan, Nigeria. Acta Vet. Brno, 55, 1986: 49-53. Diagnostic studies were undertaken on the prevalence of Marek's disease (MD) and Avian Leukoses (AL) between 1975 and 1984. Over the period, 22 cases of outbreaks of MD and 19 cases of outbreaks of AL were recorded. During this period, there were two noticeable peak incidence for MD in 1977 and 1983/84 while for AL there were three peaks in 1977, 1979 and 1983. It was observed that the lag period, from 1977 to 1983, when MD incidence remained low reflected the effect of the widespread application of MD vaccines in the advanced poultry producing countries which supplied the bulk of the Nigerian poultry. The import­ ance of diagnostic surveillance of MD is discussed. Survey, diagnosis, local vaccination programmes. Marek's disease (MD), a lymphoproliferative neoplasm of domestic fowl caused by a herpes vi­ rus, was a major disease problem and source of great economic losses in poultry until the early 1970's. The discovery of the turkey herpesvirus lyophilised vaccine for MD in 1970, was followed with progress in the control of the disease (Okazaki et al. 1970; Purchase and Schul tz 1978). Although routine MD vaccination has to-day not been adopted in Nigeria, the poultry industry appeared to have benefitted from the spill-over effects of the vaccination standard and practices in the poultry exporting countries. For this reason and because of the pathological relationship between MD and Avian Leucoses (AL) which is another economicaIly important neoplasm of poultry, a diagnostic surveillance for both diseases has been maintained in our Poultry Disease Unit (PDU) at the University of Ibadan. This paper describes the studies on MD and AL from 1975 up to date, and discusses the trend in the incidence as -well as the possible implications of these observations on the epizootiology of MD.