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expert reaction to news from UKHSA that avian influenza was detected in two individuals taking part in asymptomatic testing of poultry workers

The UK Health Security Agency (UKHSA) has detected Influenza A (H5) virus in two poultry workers following the introduction of an asymptomatic testing programme.


Prof Ian Brown, Director of Scientific Services, Animal and Plant Health Agency (APHA), said:

Does this change our understanding of the risk to poultry, poultry workers, general public from avian influenza?

“No the virus is not changing its characteristics to something more risky to humans but continued monitoring important. This event does not alter the risk to poultry from these viruses and farm biosecurity remains the most important defence. 

Does this change our understanding of the virus?

“Deep surveillance programmes of personnel in close contact with infected poultry are insightful to understand what could happen. To date out of the reported detections in humans it is clear that careful investigation and interpretation is required. Detection by PCR alone does not necessarily prove active infection and supports the virus still remains strongly avian in its tropism but programmes such as those being deployed in GB are valuable to gain better understand of the true risk these viruses currently pose to human health. The One health joined up approach being applied in GB sets best international practice for vigilance. 

Will further investigation be able to determine if these are cases of contamination?

“Investigations continue but it is possible they may return inconclusive outcomes but UKHSA should provide comment.  

Any additional comments about avian influenza in the UK and abroad?

“The virus continues to cause significant impacts for poultry production around the world. In addition there are continuing threats to wildlife biodiversity. Investment in good surveillance and research to address key knowledge gaps such as being applied in the UK are vital to inform timely action. Continued awareness and prompt reporting of disease suspicion by keepers of birds is important to mitigate continued threat.  Cooperation at international scale will be necessary for global control of the disease in birds and other species.”


Prof James Wood, Head of Department of Veterinary Medicine, University of Cambridge, said:

“It is known that the clade of H5N1 infecting birds (wild and farmed) in Europe, including the UK, can occasionally infect people but rarely causes disease. It appears that most sampling internationally has been symptomatic, so it is not surprising that asymptomatic sampling has detected infection in 2 highly exposed workers. The finding should lead to greater attention being paid to asymptomatic infection (and sampling) but does not in itself indicate that the risks have changed. It will of course be important to sequence the virus in these two workers, and the birds that they were exposed to, to determine whether there are any mutations that might be of specific concern.

“If the two positive workers are resampled, it may be possible to get an indication if they have developed an immune response to the virus, rather than just being contaminated, but this may not markedly change the interpretation of the findings.

“The scale of the epidemic in wild birds appears to have diminished since before Christmas, although infection is still being detected by APHA and it is still spilling over into domestic poultry, but at a massively reduced rate compared to during the winter. It is hoped that the epidemic in wild birds will disappear over the summer, but what will happen is hard to predict.”



Declared interests

Prof Ian Brown: “I work for APHA acting as a national and international reference centre for avian influenza. I currently lead a GB research consortium addressing gaps in scientific knowledge.”

Prof James Wood: “I receive funding from Defra / BBSRC as part of the FLUMAP consortium looking at aspects of the avian influenza epidemic in the UK; specifically my work examines biosecurity practices on poultry farms.”

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