الفهرس 
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Abstract
In this study the prevalence and characterization of avipoxviruses circulating in Sharkia governorate were investigated. Furthermore, the role of the currently used vaccine in their prevention in domestic birds was elucidated.
For this purpose 136 bird flocks from different species (75 pigeon, 35 chicken and 26 turkey), ages (from 7-60 days in pigeons, 40-120 days in chickens and 40-90 days in turkeys) were examined for the presence of APV infection.
One hundred and thirty positive samples from total 136 samples, which succeeded to induce visible pocks on CAMs with different morphological characters and different degrees of membrane thickening. The isolated viruses yielded two distinctive types of lesions on the CAMs, the classical shape of small to large, distinguishing white to yellow pocks and the other one is abundant white to yellow substantial thickening of the CAMs of different sizes.
The results of age and incidents of APV confirmed clinical cases showed that APV infections were more frequently abundant in pigeons at ≤30 days of age (81.4%) and less frequently in pigeons at ≤60 days of age (18.6%). In chicken and turkey species, APV infection was not detected at ≤ 30 days of age and virtually all the cases were isolated during the period from 30 (97%) to 90 (100%) days of age. Only one case was detected from chickens at 120 days of age. There was a seasonal peak in hot summer months between July and October in the different studied species during the period of surveillance.
The isolation results were confirmed via the presence of intracytoplasmic inclusion bodies in both skin lesions and infected CAMs.