Disease issues: AI mixed with ND in vaccinated layers

Both diseases are economically important infectious diseases in poultry. Sometime, concomitant secondary viral/or bacterial infections significantly alters the pathobiology of both ND and AI in poultry.

As of now, the disease patterns and dynamics of co-infections caused by ND virus (NDV, genotype XIII) and Low Pathogenic AI viruses (LPAI, H9N2) are explicitly elusive.

So, scientists examined the clinicopathological disease conditions to understand the complex disease outcomes by virus-virus interactions in vaccinated flocks.

The findings of clinicopathological and molecular investigations carried on 37 commercial ND vaccinated poultry flocks revealed simultaneous circulation of NDV and AIV in the same flock/bird.

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Further molecular characterisation of hemagglutinin (HA) and neuraminidase (NA) genes confirmed that all the identified AIV’s were of low pathogenicity H9N2 subtype and fusion (F) gene analysis of detected NDVs below to NDV class II, genotype XIII, a virulent type.

The NDV and H9N2 alone of co-infected flocks exhibit clinical signs and lesions similar to that of virulent NDV except the degree of severity, which was higher in H9N2-NDV co-infected flocks.

Additionally, avian pathogenic E.coli and mycoplasma infections were detected in the majority of the ailing/dead birds from the co-infected flocks during progression of clinical disease.

Overall, the scientists say the findings highlight the multi-factorial disease complexity in commercial poultry and suggest the importance of NDV genotype XIII in intensifying the clinical disease in vaccinated birds.

The abstract article is published in the journal VirusDisease