GoKawiilPeople who live in close proximity to pig farms are more likely to pick up antibiotic-resistant infections than are those who live farther away.Credit: Thomas Dodge/AgStock/Image Source Limited/Alamy
Livestock farms are producing more than they intend to. As well as raising chickens, cows and pigs, these farms are also unwittingly rearing dangerous microorganisms that are resistant to antibiotics. These microbes pose a threat not just to farmers’ livelihoods, but also to the health of farm workers and people in their wider community.
Public reaction to the use of antibiotics in agriculture has often focused on the welfare of animals and the people who consume their meat. Many health-conscious shoppers now try to avoid meat from animals that have been given antibiotics, even though there is conflicting data about whether this consumption presents a risk to humans. What is becoming clear, however, is that antibiotics endanger the health of people who work on farms.
Nature Outlook: Antimicrobial resistance
Liberal use of antimicrobial drugs on farms — including those that produce fruit rather than meat — can result in pathogens becoming impervious to these essential medications. These drug-resistant organisms can cause infections in farm workers that are difficult to treat and can spread to other people. This situation has raised concerns among workers’ rights groups and scientists studying the rise of antimicrobial resistance (AMR). “The use of antimicrobial drugs, in the quantities used in food animal production, poses a risk to human health,” says Christopher Heaney, an infectious-disease researcher at Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. “Workers are at the front line of that.”
One of the earliest connections between antibiotic use and drug-resistant microbes was made by scientists studying methicillin-resistant Staphylococcus aureus (MRSA) bacteria. MRSA is highly contagious and spreads in hospitals and nursing homes worldwide. It typically infects the skin, causing varying degrees of tissue damage. However, if it reaches the blood, it can have a mortality rate of between 20% and 50%.
The dominant type of livestock-associated MRSA, called CC398, is becoming increasingly prevalent on farms. In Denmark, where surveillance of antimicrobial-resistant microbes in agriculture is particularly good, the proportion of pig farms with MRSA-positive herds jumped from less than 5% in 2008 to 90% in 20181.
CC398 is also increasingly infecting people — including those who do not have direct contact with farm animals. People who live in close proximity to farms are at greatest risk, but others are also affected. An analysis published last year reported that people living between 1.25 kilometres and 6.25 kilometres from pig farms in Denmark picked up infections when the wind blew from farms towards their communities2.
Because the threat posed by AMR in agriculture is invisible, it is often overlooked. Qamar Saeed, a microbiologist at Bahauddin Zakariya University in Multan, Pakistan, contrasts this threat with chemical hazards found in smoke from a fire. “People know there is smoke, and they get uncomfortable around it,” he says. “But antimicrobial resistance, it’s a silent hazard.”
Evidence of the scale of the hazard has nonetheless been mounting over the past couple of decades. One study published in 2007 found that people who worked on intensive poultry farms were 32 times more likely to be infected with an antibiotic-resistant strain of Escherichia coli — a leading cause of urinary tract infections (UTIs) — than were members of the general public3. And a 2022 study found a higher rate of antibiotic-resistant bacteria in sewage waste from poultry farm workers than in sewage from household toilets4.
... continue reading