What could the latest US bird flu findings mean for our food industry?

The threat of bird flu has largely been avoided in the UK over the past year.

Unlike in 2022/23, when the disease threatened to bring the poultry and egg supply chains griding to a halt, the past 12 months have largely passed with minimal incident.

In fact, just six cases of highly pathogenic avian influenza (HPAI) have been confirmed in the UK since last October, with Defra declaring “zonal freedom” from HPAI in Great Britain on 29 March of this year. Northern Ireland declared itself free on 31 March 2023.

While the current risk of bird flu is “low”, according to Defra – given avian flu’s potential to devastate bird (and more to the point commercial poultry) populations – many in the sector have been quick to express caution since the dark days of late 2022 and early 2023.

And given the news this week that the disease is also taking a troubling turn towards other animal species and even humans, that caution looks well placed.

Concern over the spread of bird flu from wild birds into cows first reared its head in the US on 25 March, after the US Department of Agriculture, the Food and Drug Administration and the Centers for Disease Control and Prevention jointly announced the H5N1 strain of HPAI had been identified in US dairy cattle for the first time.

Is bird flu infectious to others? 

By late April, the USDA had ordered the dairy industry to test milk-producing cows for infections from bird flu. This followed, on 23 April, confirmation that samples of pasteurised milk sold in American supermarkets had tested positive for traces of the virus.

H5N1 has now been confirmed in cattle on more than 100 farms in 12 states, while four people – known to have worked with infected animals – are also known to have contracted the virus, though health officials said symptoms were mild and the virus had not been transmitted on to others.

But despite the seemingly low risk attached to these transmissions, a report published this week warns that the threat of the virus mutating and becoming more virulent is now a clear danger.

The study, published in medical journal Nature, revealed that mice which drank milk from a cow from New Mexico that was infected with bird flu then became infected themselves. They also passed on the virus to their pups via their own milk, the study found.

This meant that bird flu could now be spread via the mammary glands of mammals and be passed on through their milk, reported The Times on Monday. This represented a new disease-spreading vector that had not been investigated while the virus was thought to be contained to birds – which do not possess mammary glands.

The study’s findings were “of concern” , Dr Ruth Harvey, deputy director of the Worldwide Influenza Centre at the Francis Crick Institute, told The Times.

Is there a H5N1 bird flu vaccine? 

“It suggests a possible increase in the potential of this virus to infect other mammals, including humans, although more research is needed to confirm how this would happen in practice,” she added.

Meanwhile, Dr Ed Hutchinson from the Medical Research Council and University of Glasgow Centre for Virus Research was even more alarmed, telling Sky News “this new H5N1 influenza virus would be even harder to control, and even more dangerous to humans, if it gained the ability for effective respiratory spread”.

Hutchinson was keen to stress that the disease could not yet transmit in this way, but the findings “reinforce the need for urgent and determined action to closely monitor this outbreak and to try and bring it under control as soon as possible”.

Covid vaccine maker Moderna is already working on a H5N1 vaccine, having been awarded $176m in funding by the US government a few weeks ago, while the EU has already secured 40 million doses of a different jab made by Australia-based manufacturer CSL Seqirus in preparation for an upturn in the disease’s spread on the continent.

UK drugmaker GSK and German biotech CureVac were also jointly developing their own avian flu vaccine in early trials, reported the Financial Times last month.

The risk of this disease spreading further than the US dairy herd may well be low at the moment, but after the damage wrought by earlier outbreaks of bird flu across the food sector, not to mention the experience of the Covid pandemic, a safety-first approach to tackling any future threat looks to be a very prudent move.