Plan for the worst this winter with Avian Influenza, producers were advised earlier this month.

Current viral activity suggested a likely threat again this winter, said Gordon Hickman, Head of Exotic Disease Control at Defra Animal and Plant Health Agency (APHA), at a special session on avian influenza at Poultry Network Live in early September.

See also: Dutch begin field trials of avian influenza vaccine

In total, there were 201 infected premises in the current outbreak year just ending, compared with 150 last year.

“We think it’s unprecedented in terms of scale,” said Mr Hickman.

The vast majority (132) were in large commercial premises, with 44 in backyard flocks. 

Wild bird incursions

However, backyard flocks were classed as “sentinels” and not “really” involved in spreading disease.

“Virtually all outbreaks are assessed to be individual incursions from wild birds into those sheds”. This made the biosecurity measures really important, stressed Mr Hickman.

This was in contrast to the picture found in continental Europe, particularly France, where spread from farm to farm was considered the main factor. 

The infection pressure had been unprecedented from wild birds in the current 2022-23 infection season, he said. 

New season

The virus had already over-summered twice during the current epidemic, and the new season would begin on 1st October.

The virus was now persisting in the environment all year round by shifting from migratory birds such as geese to resident seabirds, especially black-headed gulls. 

These may have transferred the infection to ‘gull gangs’ which were typically seen on landfill sites, following cultivators, or sitting on factory roofs and poultry sheds.

Although the most recent wild bird findings had all been in coastal areas, they were still thought to be the current year’s outbreak rather than the “next one starting early”.

Next winter

“What’s going to happen next year? I genuinely don’t know. We can’t model this, because we can’t tell how many wild birds will get it. It may not even be the same virus that comes back next year.”

“We are preparing ourselves for something that looks a bit like last year, in terms of the pattern of events,” he said.

However, the numbers could possibly be lower numbers because of cross-protection in wild bird species, and because “you guys have all upped your game.”

“We are cautiously hopeful it won’t be as bad as last year.”

Vaccination

There was no immediate prospect of vaccination, continued Mr Hickman.

“We are not convinced there is any vaccine technology available to the UK that meets all of our needs.”

“Vaccination is not a silver bullet. It will only work in combination with other measures, in particular biosecurity and outbreak control.

“We need to be able to differentiate vaccinated and non-vaccinated birds in order to carry out surveillance and reassure trading partners we haven’t got undisclosed disease.”

Surveillance

So even if a vaccine was introduced, the cost of the necessary surveillance could be around £1,500 a shed on top of the vaccine cost, he said.

“In most cases, that’s not going to be cost-effective.”

Dr Mike Clarke, president of the British Veterinary Poultry Association, said that vaccination may be required to control HPAI in the UK, but “should not be undertaken lightly”.

It would only happen if certain conditions were met:

  • There would have to be the political will, both in the UK and globally;
  • The net financial benefit to the industry was greater than the status quo;
  • And if the market was large enough to justify the commercial development of a vaccine.

It wouldn’t happen if post-vaccination testing (surveillance) was too onerous or expensive, or if the compromise to trade was too great, he warned.

Julian Sparrey of Livetec Systems said the most critical area for biosecurity was the 20m cordon closest to buildings. 

Biosecurity

Maintaining biosecurity at the farm gate is generally less cost-effective.

“Think about where your best investment in biosecurity should be.”

All the measures taken should be easy to comply with for staff and visitors, compared with not complying. 

Research has shown that where footwear was changed, for example, this was more likely to be complied with for longer visits in the biosecure area than for briefer ones.