Abstract
Objective: Since 100 years ago, the avian leukosis virus (ALV) was discovered but has remained a threat to poultry production globally, inducing neoplastic diseases of different pathotypes, immu¬nosuppression, growth retardation, and a drop in egg production, thereby resulting in great eco¬nomic losses for both commercial and local poultry farmers. This study investigates the status of the ALV in commercial poultry farms in Kaduna State, Nigeria.
Materials and Methods: Two hundred and fifty sera samples were collected across five local governments in Kaduna State, Nigeria, between January 2017 and May 2018: Chikun, Lere, Kaduna North, Kaduna South, and Sabon Gari and were screened for ALV using the enzyme-linked immu¬nosorbent assay.
Results: A total prevalence of 78.9% (CI: 73.4–83.53) was recorded. The highest prevalence of 82% (CI: 69.53–90.85) was recorded in a commercial poultry farm in Sabon-gari; 80% (CI: 67.24– 89.37), 78% (CI: 64.99–87.85), 78% (CI: 64.99–87.85), and 76% (CI: 62.77–86.3) were recorded for Kaduna North, Lere, Kaduna South, and Chikun commercial poultry farms. For layers, cockerels, and broilers, the detection rate was 86.5% (CI: 79.99–91.58), 75.0% (CI: 24.23–98.75), and 69.6% (CI: 60.66–77.62). At the age level, the highest rate was recorded in older birds, with 86.7% (CI: 74.32–94.41), while 77.1% (CI: 70.7–82.44) was recorded for the young birds, with no significant difference (p > 0.05) between the two age groups.
Conclusion: The study indicated that ALV is prevalent in commercial poultry farms in Kaduna State, Nigeria. It was recommended that further studies be conducted on the molecular charac¬terization of the virus. Adequate preventive and control measures must be implemented because the economic impact of ALV on the poultry industry is enormous.

Key words: Avian leukosis virus; commercial poultry; ELISA