Approaches to Control Avian Lymphoid Leukosis

In the past, the eradication of lymphoid leukosis (LL), the most common pathological manifestation of avian leukosis virus (ALV) infections in chickens, could only be pursued by elimination of all diseased birds from a given flock. This approach was only successful if the initial incidence of ALV infection was low. Waters and Prickett (1) obtained an ALV-free flock (line 15I) at the Regional Poultry Research Laboratory, East Lansing, Michigan, by careful selection and isolation of families having low incidence of the disease. There are a few earlier reports on leukosis control, but at that time the etiology of the Avian Leukosis complex was not clarified, and it is unclear whether the described investigation referred to LL or classical Marek’s disease (2).