First ever UK case of “reverse zoonosis” as human flu found in factory-farmed pig

The Green Britain Foundation has uncovered a groundbreaking health revelation: the human seasonal flu virus (H3N2) has been detected in a UK pig for the first time.

This marks the first recorded case of “reverse zoonosis” in the UK; where a virus is transmitted from humans to animals. The finding was buried within government surveillance data from a Northern Ireland pig farm, detailed on page 17 of the Animal & Plant Health Agency (APHA) Great Britain Pig Disease Surveillance Report (July–Sept 2024).

The affected farm also reported swine flu among its pigs, raising major concerns about viral recombination, when human and animal flu strains mix, creating new variants.

While similar human-to-pig transmissions have been recorded in the United States, this UK case had not been publicly highlighted until GBF’s investigation.

A warning from the Green Britain Foundation

Dale Vince, founder of the Green Britain Foundation, said:

“We’ve seen bird flu in humans and now, buried in a government report, we’ve found evidence of human flu in pigs for the first time.

How long will we wait before these preventable diseases trigger another pandemic? We need to overhaul our relationship with animals and radically rethink our food systems.

These zoonotic diseases are a direct result of how we treat animals — particularly in factory farming systems where animals are kept in overcrowded and stressful conditions that act as breeding grounds for disease.

Reducing meat consumption and transitioning to sustainable farming practices are not just ethical imperatives — they’re essential for protecting public health and safeguarding our planet.”

Expert insight

Veterinary Professor of Animal Welfare and Ethics Andrew Knight reinforced the link between intensive farming and zoonotic risk:

“Intensive pig and poultry farms crowd vast numbers of stressed animals in close proximity, often in conditions of very poor hygiene. If someone wanted to create ideal conditions for rapid transmission of disease, they could hardly do better.

It’s no wonder influenza keeps breaking out within intensively farmed poultry flocks, with evidence of transmission to humans. And now we also have a pig infected by a human.

Influenza has killed more people in history than any other disease outbreak. Intensive pig and poultry farms are ticking timebombs from which the next outbreak may very well arise.

For the sake of human and animal health and welfare, they should be closed.”

Factory farming: a health and climate threat

The Green Britain Foundation is calling for urgent measures to address the multiple risks posed by factory farming, including:

• Phasing out intensive animal agriculture

• Reducing meat consumption

• Transitioning to sustainable, humane farming systems

The Foundation warns that factory farming is not only a breeding ground for zoonotic disease, but also a major contributor to the climate and biodiversity crises.

The case for change

Factory farming represents interconnected risks:

• Public health: Facilitates zoonotic diseases such as swine flu, bird flu, Covid-19 — and now, reverse zoonosis with H3N2.

• Dietary health: Overproduction of cheap meat drives excessive consumption linked to chronic illnesses such as heart disease, cancer and obesity.

• Wildlife loss: Feed crop expansion and land-use change destroy ecosystems critical to biodiversity.

• Climate impact: Industrial livestock farming is a major source of methane, deforestation and carbon emissions.

A call to act on the evidence

This case of human-to-pig flu transmission underscores the urgent need for:

• Expanded surveillance of flu viruses capable of crossing species barriers

• Transparent public reporting of disease outbreaks linked to farming

• A transition away from intensive animal agriculture to safeguard both people and planet

The Green Britain Foundation argues that factory farming is not sustainable, ethical, or safe, and that a shift to plant-based, regenerative, and humane food systems is essential to protect future generations from the next pandemic.