Chapter X Strategies in the diagnosis of AI

United Kingdom

As set out in Annex IV to Directive 2005/94/EC, decisions to apply measures in specific areas or contact holdings and the severity of those measures may vary greatly with the magnitude of the risk. Similarly, the required diagnostic confirmation of disease is likely to be balanced against the prevailing situation, the magnitude of the hazard and the degree of risk. Veterinary authorities need to make decisions on diagnostic evidence that balance the rapid control and eradication of disease against the potential impact of misdiagnosis. Such judgements have to be made against the background of many factors at the time, but certain situations can be predicted.

Disease situation	Potential problem	Diagnostic criteria
For these full sampling should be carried out and samples stored for later evaluation.
Non specific signs, no official suspicion	Isolated holding	Carry out rapid detection based on M gene RT-PCR. Differential diagnosis as required
Primary suspected outbreak	Isolated holding	Carry out full diagnostic testing, virus isolation and characterisation
Primary suspected outbreak	Holding in densely populated poultry area	Carry out full diagnostic testing, virus isolation and characterisation, but concentrate on rapid detection and characterisation methods especially those based on RT-PCR and sequencing^f1.
Second and subsequent suspected outbreaks	Isolated holdings, epidemiologically linked to primary suspected outbreak	Concentrate on rapid detection and characterisation methods especially those based on RT-PCR and sequencing.
Second and subsequent suspected outbreaks	Holdings in densely populated poultry area or with many epidemiological links	Rely on rapid detection methods that give the earliest evidence of the presence of any AI virus.
Multiple suspected outbreaks or disease spreading rapidly including surveillance	Spread will become uncontrollable without rapid intervention	Rely on rapid detection methods that give the earliest evidence of the presence of any AI virus or rely on clinical signs.

Annotations

Footnotes

f1: For these full sampling should be carried out and samples stored for later evaluation.