An adenovirus infection of poultry in Pakistan

A previously unknown disease which has spread among broiler poultry farms in Pakistan, attacks well-growing chicks at 3-5 weeks of age, with 30 to 60% mortality. At necropsy, the most prominent lesion is hydropericardium. Lungs are congested and oedematous, and liver and kidneys are pale and swollen. Histologically, there was necrosis and severe vascular changes in the heart as well as congestion, oedema and inflammatory cell infiltration in the lungs. Focal necrosis and mononuclear cell infiltration were present in the liver and many hepatocytes contained large, basophilic, intranuclear inclusions. The disease was reproduced in 15-day-old broiler chicks by subcutaneous inoculation of liver homogenate. The liver homogenate also caused stunted growth and haemorrhages when inoculated into embryonating eggs. Virus particles with icosahedral symmetry were seen by electron microscopy in purified liver extract. The disease is believed to be caused by a hitherto unreported adenovirus. However, the role of some other potentiating factor cannot be ruled out at this stage.