Lymphoid Leukosis
Lymphoid leukosis is a common disease caused by avian sarcoma
virus characterized by marked enlargement of liver and nodular growth on
bursa. Generally occurs after 14 weeks of age, however highest incidences are
during sexual maturity in laying hens and breeders.
It is transmitted both vertically through egg and also horizontally from bird to bird by direct contact.
Though vertical transmission is minimal majority becomes infected by contact with vertically infected chicks.
Vertical transmission from hens through egg albumen as shedding of virus happens by albumen secreting glands.
Immunosuppression caused by IBD increases the rate of shedding of virus.
Resistance increases with age.
Females are most susceptible than males.
Symptoms are non specific with pale shrivelled or cyanotic comb.
Liver Lesions: Liver is greatly enlarged and the pattern of involvement is
usually diffuse or miliary but can occasionally be nodular. That is, may
reveal grossly visible tumours. Tumours are soft, smooth, and glistening.
