Seroprevalence of avian leukosis virus antigen using ELISA technique in commercial exotic-layer chickens in Zaria and its environs

This study examined the prevalence of avian leukosis virus (ALV) in commercial exotic-layer chickens in Zaria, Nigeria, and its environs. A total of 240 sera from eight commercial exotic-layer farms were tested for ALV p27 antigen using the antigen capture enzyme linked immunosorbent assay (ac-ELISA), out of which 44 (18.33%) sera were positive. Of the eight commercial exotic-layer farms sampled, six were seropositive for ALV, while two were seronegative. The six farms seropositive for ALV had seroprevalence of 20.0, 11.4, 14.3, 8.6, 16.7 and 66.7%. All serum samples from exotic commercial layers that tested positive to ALV p27 antigen were lowly positive, except for farm VIII, where 11 of the 20 positive samples were lowly positive with EUs ranging from 11 to 22.6%, and 9 of the positive sera were moderately positive with EUs ranging from 28.7 to 62.8%. The average age of exotic layers from the ALV p27 antigen positive farms was 17.2 (SD=1.3) weeks. At the time of sampling of chickens from the six farms that tested positive to ALV p27 antigen, the farms had lost between 6.25 and 37.5%, and an average of 20.8% (SD=13.2) of the total chickens stocked. The average mortality rate per week for the ALV p27 antigen positive farms was approximately 2.6% (SD=1.7) with farm I having the highest mortality rate of 5%, and farm VIII lowest with a weekly mortality rate of 0.75%. These findings illustrate the potential severity of ALV infection and its economic consequences in this region.