Clinical observations and pathology of the reproductive tract associated with natural infection of an avian influenza (AI) virus in an AI vaccinated layer flock

The report appears a well documented evidence of reproductive tract damage by the AI virus. However, it is unusual that mortality returned to normal figures in about 2 weeks. In our experience, once a layer flock gets AI virus challenge during production, mortality increases and then decreases but never to normal mortality figures. There remains persistent higher mortality throughout the life of the flock. Was any differential diagnosis made for IB variants?

Distinguished Dr. We appreciate your valuable comments. In fact, the behavior of the percentage of mortality in the flock was the one we mentioned in the paper, is a fact that seemed very important given the characteristics of the virus in question. Regarding your question about IB variants we can not assure you if they were present or absent because we could not manipulate samples to perform serological searches or viral isolations due to the nature of the AI virus.

I want to share with you the experience we have had with the IB virus. When IB + IA of low + Mycoplasma is present, these three agents generate a very important synergy that complicate the respiratory pictures. The association Mycoplasma with low pathogenic AI is important, but when IB is involved, the picture becomes very aggressive, especially, cases of caseous plugs are present and the percentage of mortality increases, which does not happen when only Mycoplasma and IA with low pathogenicity. regards

Agreed! synergy increases losses, both in young birds as well as in laying birds. However, we do see caseous plugs in bronchi in field outbreaks in broilers and pullets, not in adult laying birds.

The behavior of bronchitis in young birds (1 to 7 days of age) is a characteristic caseous plug; In the case that I mention is the presence of caseous plug in birds in production, but here the interesting thing is the respiratory complex that occurs in which are involved: Mycoplasma, low pathogenic AI and IB.