A century-old alternative to antibiotics goes modern — here’s why it matters
published on
01/21/2026
Bacterial infections are already the second leading cause of mortality worldwide. For over a century, phages have been used to kill bacterial strains. However, this treatment has been largely sidelined since the discovery and widespread adoption of antibiotics. In 2025, France approved phage-based veterinary treatments, bringing them for the first time under a formal regulatory framework. As antimicrobial resistance (AMR) continues to limit the effectiveness of antibiotics, phages are being reconsidered as promising alternatives.
Bacteriophages, or phages, were first observed by Frederick Twort in 1915. Two years later, French microbiologist Félix d’Hérelle made the same discovery independently. He named them ‘bacteria eaters’ in Greek and became captivated by their potential. D’Hérelle dedicated his career to phage therapy, successfully treating dysentery patients even before fully understanding how they worked.
Today, we know that phages are viruses that infect bacteria, each capable of killing one or only a few bacterial strains, without harming human or animal cells. They work by injecting their DNA into bacteria, reprogramming the cell to produce new phages until the cell bursts, and releasing new phages to continue the cycle.
So why was this promising therapy abandoned? When penicillin was discovered, it eventually became the preferred treatment and was easy to manufacture in large quantities. Phage therapy was discarded because scientists lacked the technology to scale it.
The challenge of antimicrobial resistance
The misuse, overuse, and improper disposal of antimicrobials have driven the global rise of AMR. The World Health Organization (WHO) reports that one in six lab-confirmed bacterial infections no longer responds to traditional drugs, with antibiotic resistance globally worsening by 5-15% annually. Already, 3,500 people die each day as a direct result of the AMR crisis.
However, AMR is not a problem confined to human health. It impacts animal health by reducing the effectiveness of treatments for infections. The economic stakes are enormous with land animals contributing 25% of agricultural GDP in low-and-middle income countries and nearly 50% in high-income countries with an estimated 20% of production already lost to disease.
With the high costs to develop new antibiotics, the world is urgently looking for new alternatives to combat AMR.
Technology has finally caught up. Entire genomes can now be sequenced quickly and affordably. Artificial Intelligence (AI) helps make sense of these massive datasets to better our understanding of how phages and bacteria interact.
The result? Taking the guesswork out of phage therapy and the ability to quickly design and update medicines at the pace needed to stay ahead of bacterial resistance.
Bacteria and phages are in constant co-evolution, meaning there will always be effective phages which can be used for medicines. Techniques such as directed evolution can also be used to increase a phage’s effectiveness against its bacterial target. This means phages can even be effective against superbugs. Studies have even demonstrated that rotating between antibiotics and phages can create synergies and be an extremely effective treatment for superbugs. When bacteria adapt to resist antibiotics, they often become more susceptible to phages and vice versa.
Used in animals, phage therapy offers highly targeted bacterial elimination without disruption to the animals’ microbiome thanks to their inherent specificity – one phage is effective against one or a few bacterial strains.
France approves world’s first phage platform for animal health
In a groundbreaking regulatory milestone, the French Agency for Veterinary Medicinal Products has granted the country’s first authorisation to market personalised phage-based veterinary drugs. This decision represents a major turning point in how bacterial infections are fought, marking the transition from experimental therapy to a viable commercial treatment.
This regulation recognises phage therapy as a platform technology. This indicates that a medicine’s formulation may be continually updated through the platform so that treatments can stay ahead of bacterial resistance unlike static, chemical drugs.
What this means in practice: Veterinarians can now access legally approved phage treatments that are tailored to the exact bacterial infections they’re treating, expanding their arsenal of tools for animal health. This regulatory precedent arrives at a critical moment. The first company to receive this approval has begun field deployment, and the resulting real-world evidence will be crucial for regulators worldwide evaluating phage therapy for animal health. This could pave the way for broader adoption across Europe and globally.
Good news for humans, animals and the environment
Antimicrobial residues and resistant bacteria enter the environment through multiple pathways, including human wastewater, hospital effluent, and agricultural runoff. They can disrupt ecosystems and spread resistance genes across microbial communities in soil and water. These residues can also accumulate through the food chain with known and unknown One Health effects
Phages, as biological entities ubiquitous in the environment and the human microbiota, pose no such concern. They ignore all other cells, and once their targeted bacteria is no longer available to serve as hosts, they are cleared naturally from the body by the immune system. When used in animal medicines, no withholding period is required.
The case for broader adoption is compelling across stakeholder groups:
| Veterinarians | Farmers | Food industry | Consumers |
| Gain new treatment options for antibiotic-resistant infections | Maintain productivity while preserving beneficial microbes and reducing economic losses |
Access effective alternatives for antibiotic-free production systems |
Reduce exposure to antibiotic-resistant bacteria through the food chain |
Global Implications and Future Outlook
By offering precise, adaptable, and environmentally safe treatments, phages could become a critical tool in protecting human and animal health worldwide.
France’s regulatory breakthrough establishes a precedent that other countries can reference when developing their own phage therapy approval pathways. The first large-scale field deployments will generate real-world evidence that regulatory agencies worldwide can evaluate. As more countries observe this model and review emerging data, further approvals are expected in the coming years.
After a century in the shadows, phage therapy is re-emerging in scientific discussions. The question is no longer whether phages can work, but how quickly this solution can be adopted to and support global health.
The Animal Echo aims to promote individual and collective understanding of animal health and welfare. We bring you insights and opinions from experts across the world. The opinions expressed in The Animal Echo are those of the author (s) and may not necessarily reflect WOAH’s official position.
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