Campylobacter: a silent risk in our farm animals, wildlife and the wider environment

Farm safety is not just about visible hazards, it also includes biological safety, managing unseen risks from microorganisms like Campylobacter.

As early as the 1960s, health care providers were discussing how human health is closely linked to the health of animals and the environment. This is when veterinarian Calvin Schwabe coined the term ‘One Health’. Today, One Health is an accepted concept that takes a holistic view of our living space, including people, animals, plants, and the environment, and the connections between them.

The work we carry out in the APHA National Reference Laboratory (NRL) for the bacterium Campylobacter aligns with this ethos. We focus on surveillance and research of this microorganism in animals, their products, and the environment, linking this to the risks these organisms pose to human health.

These risks highlight why everyday actions on farms play a crucial role in protecting both human and animal health.

A common but less recognised risk

Campylobacter is a bacterium that can live in birds and mammals. When present in animals, it can contaminate food and the environment, creating a public health risk. If people consume contaminated food or water, they may develop the disease campylobacteriosis, which typically causes diarrhoea, cramps and fever.

Although most infections resolve within a week, some cases can lead to serious complications such as sepsis, reactive arthritis, or irritable bowel syndrome. The disease is widespread globally, with an estimated 600,000 cases annually in the United Kingdom (UK), costing the UK economy around £700 million each year.

This demonstrates how an invisible biological hazard can have significant impacts on individuals, workplaces, and society.

False colour scanning electron micrograph of Campylobacter jejuni A zoonotic threat in a connected world

Campylobacteriosis is a zoonotic disease, meaning it can spread naturally between animals and people. The World Health Organisation notes that most emerging infectious diseases in humans are zoonotic. This makes it essential for APHA to monitor such risks as part of its mission to protect animal and plant health for the benefit of people, the economy, and the environment.

Unlike in humans, Campylobacter often lives harmlessly in animals. However, in livestock such as cattle and sheep, it can sometimes cause infertility, stillbirths, and reduced productivity, showing its importance for both animal welfare and farm economics.

These examples illustrate why farm safety includes biological safety and shows the impact of APHA’s science: protecting animal health, supporting food system resilience, and improving the UK’s ability to anticipate and manage emerging biological threats.

Simple actions that protect us all

Reducing the spread of zoonotic and veterinary diseases, including Campylobacter, is supported by simple, practical actions:

Do not bring risk onto farms. Avoid bringing meat or animal products from outside the UK Do not feed or interact with farm animals unless permitted Maintain hygiene. Clean clothing, footwear, equipment and vehicles before and after visiting farms Report disease early. Early detection helps prevent wider spread Detecting Campylobacter: science behind the scenes

An essential quality driving the One-Health importance of Campylobacter is its distribution across our living space, readily persisting in poultry, livestock, wildlife and freshwater environments.

As a microbiologist, I have always been intrigued by the paradox of how Campylobacter is so successful in nature despite being fragile. Oxygen in the atmosphere is toxic to it, and it has limited energy sources, yet it thrives across many environments.

In our laboratories, we use specialist techniques to grow and detect Campylobacter from samples such as animal swabs, intestinal contents, and environmental material. Identifying Campylobacter among many other microorganisms is challenging, and we must determine which of the 30+ species are present, as only some are significant for public or animal health.

About 20 years ago, early in my scientific career, I remember identifying a Campylobacter insulaenigrae from a seal sample - an unusual and interesting find to me, although not strongly linked to disease risk. More commonly, we encounter Campylobacter jejuni, the primary cause of illness in people.

People can be exposed to C. jejuni via many routes, with foodborne exposure a major element. Poor handling and preparation of raw meats, in particular chicken, are identified as a risk for illness, illustrating how risks can be transferred from farm to fork.

In the veterinary context C. jejuni, along with another species C. fetus can cause disease in cattle and sheep.

From laboratory insights to farm safety

At APHA, we undertake research and surveillance describing the incidence of Campylobacter within our food-producing animals. Our evidence can inform the areas of greatest risk and identify if new threats are emerging, for example Campylobacter, that are resistant to important antibiotics that may be used in veterinary and in medical treatments. This can mean studies on our farms, abattoirs and further afield, using cutting edge contemporary technologies. As Campylobacter team lead, Dr Sam Connelly, explains:

"Our work can detect threats but also provide evidence to support mitigations. We do this using several methods, and we are like detectives piecing together scientific evidence. We can inspect colonies of Campylobacter on a plate to give some primary indication of our target. Next, we use the MALDI-TOFa device which uses lasers pointed to generate a unique fingerprint used to identify any Campylobacter of interest.

One of the areas of expertise I have been able to bring into the team is a wealth of knowledge in sequencing technologies."

Genome sequencing allows us to examine the bacterium’s genetic blueprint, helping us identify traits such as antimicrobial resistance or enhanced survival.

While this work happens in specialist laboratories, the insights directly inform how risks are managed on farms and across the food chain. This includes improving hygiene practices, refining biosecurity protocols, and supporting safer farming methods.

Images showing Campylobacter on petri dishes with ertapenem antibiotic strips. An antibiotic-sensitive strain is shown in the left image, and a strain with reduced sensitivity is shown in the right image. Areas of growth are a hazy red on the plate. The large upside-down teardrop indicates an area of cell-killing.

Surveillance data becomes even more valuable when combined with insights from public health and food safety partners. Half of human infections are linked to food, but the remainder come from environmental exposure.

A notable example occurred during a cycling race in Belgium, where competitors rode over roads contaminated with livestock waste. Many cyclists subsequently developed campylobacteriosis. This real-world example highlights how easily biological risks can spread into shared environments, reinforcing why good hygiene and awareness are essential parts of farm safety.

At APHA, we are also investigating the role of wildlife, with an enthusiastic PhD student learning how Campylobacter in wild birds is linked to our farm animals, the environment, and the public, further strengthening the One Health approach.

A shared responsibility

So, in my 20 years of working on Campylobacter, I have learned a lot and enjoy working with a wide range of colleagues new and old. APHA, the wider scientific community and stakeholders have also learned much in this time. However, the threat from Campylobacter as a zoonotic and veterinary pathogen is resilient and evolving, with new species, new diseases and antimicrobial resistance emerging in this time.

APHA continues to evolve in response, adopting new technologies, training new scientists, and working closely with partners across government, industry, and academia.

Campylobacter reminds us that not all farm risks are visible. By combining science research, surveillance, and simple everyday actions, we can reduce the threat posed by these bacteria.

Farm safety includes biological safety, and everyone has a role to play in managing these risks.

The current Campylobacter team: Janie Pereira (front left), Jaime Riccomini Closa (front right), Megan Canon (middle left), Megan Horney (middle right), Claire Sawyers (back left), and Sam Connelly (Team lead, back right).

https://aphascience.blog.gov.uk/2026/07/06/campylobacter-a-silent-risk-in-our-farm-animals/

seen at 14:43, 6 July in APHA Science Blog.