Veterinary Diagnostics: The First Line of Defence Against Human Infectious Diseases

Imagine a farmer noticing a few sick chickens. At first, it seems unremarkable. But within days, other animals fall ill. The disease slips past fences – carried by birds, traded animals or even contaminated equipment. Soon, the same pathogen reaches people. What began in a single barn, forest or market ripples across borders and disrupts entire economies. Could this have been stopped earlier? Very likely. A simple diagnostic test, available at the farm gate or veterinary clinic, could have flagged the disease before it spread. With early detection, quarantine measures could have contained the outbreak, protecting lives, livelihoods and billions in economic losses. That is the power of veterinary diagnostics. These tools are the world’s most effective early warning system, detecting diseases in animals before they spread to humans or across borders [1]. Yet, in many countries, diagnostics remain overlooked, underfunded or out of reach. Investing in them could safeguard not only human lives but also protect animals and the environment.

The value of veterinary diagnostics is demonstrated in multiple areas of global health. Rabies, for example, continues to cause more than 59,000 human deaths each year, predominantly in children. While the disease is fully preventable through vaccination, effective control depends on the early identification of infected animals, such as dogs or wildlife, and limiting its spread relies on targeted vaccination programmes [2]. Similarly, the transmission of avian influenza (H5N1) from birds to cattle underscores the importance of active surveillance and polymerase chain reaction (PCR)-based testing, without which detection would occur too late to prevent large-scale consequences [3]. Foodborne diseases such as salmonellosis and campylobacteriosis, which cause millions of cases of illnesses and over 100,000 deaths annually, also illustrate the role of veterinary diagnostics in protecting public health [4]. Proper livestock testing prevents contaminated animal products from entering the food chain.

Antimicrobial resistance (AMR) presents another dimension to the challenge. Evidence from Egypt, Nigeria and South Africa shows the widespread use of antibiotics in poultry and fish, often without prior diagnostic confirmation, leading to the emergence of resistant bacterial strains [5]. Expanding access to bacterial culture and sensitivity testing would help veterinarians cut down on antibiotic use and slow AMR. This concern has also been recognised at the highest political level. In the 2024 United Nations Political Declaration on Antimicrobial Resistance, Member States committed to ‘invest in animal health systems to support equitable access to essential veterinary services, improve animal health and appropriate management practices to prevent infections, and promote the timely supply of quality and affordable essential veterinary medicines, vaccines and diagnostics, and improve veterinary oversight of antimicrobial use in animals at national level’ [6]. This global commitment highlights the urgent need to prioritise veterinary diagnostics as a critical tool for guiding responsible antimicrobial use and slowing the rise of resistance.

These examples show that veterinary diagnostics are not just technical tools but lifesaving solutions that guide smarter decisions in treatment, vaccination and disease control on a global level. Ranging from serological, microbiological and molecular assays, veterinary diagnostic tools help detect and characterise disease-causing agents [7]. Such tools provide veterinarians with evidence to detect diseases at an early stage and select the most appropriate treatment options, thereby avoiding unnecessary antibiotic use [8]. They also play a role in preventing disease transmission across species, determining the need for vaccination and responding effectively to outbreaks, limiting economic losses. Moreover, diagnostic tools can help nations prepare for deliberate biological threats such as bioterrorism [9]. In the absence of accurate diagnosis, measures such as vaccination and surveillance systems risk being misdirected. For example, the use of the wrong vaccine strain during a foot and mouth disease outbreak not only wastes resources but can exacerbate the spread of infection [10].

The Access Gaps that Leave us Vulnerable

Even where diagnostic tools are available, access to them remains uneven worldwide. In many countries, high-quality veterinary diagnostics are out of reach, leaving animals, humans and environmental health systems vulnerable. Multiple factors contribute to this gap. The high cost of diagnostic kits is a significant barrier, compounded by shortages of trained personnel to collect samples and conduct tests. Weak regulatory oversight and inadequate quality control further reduce confidence in the results. In addition, the absence of harmonised international standards prevents mutual recognition of diagnostic outcomes across borders, creating a further obstacle to coordinated global disease control.

Regulatory frameworks for diagnostic kits also vary widely. While some countries have established strict approval processes, others lack formal systems altogether. This inconsistency forces manufacturers to navigate confusing rules, including multiple approval pathways and repeated testing across different markets. Such fragmentation slows innovation and limits access, particularly in developing countries [11].

Harmonisation refers to the creation of shared rules governing the development, testing and approval of diagnostic tools. It ensures that diagnostic kits meet international standards and can be relied upon across borders. Achieving this objective, however, is far from straightforward. Efforts to harmonise veterinary diagnostics are hindered by differences in national legal systems and technical capacities, the absence of agreed validation protocols, limited data-sharing, as well as mutual recognition and uneven levels of support from national authorities. Despite these challenges, the potential benefits are substantial: reduced costs, better access and faster responses to disease outbreaks.

Bridging the Diagnostic Divide

To tackle these challenges, the World Organisation for Animal Health (WOAH) has taken several important steps. It has developed international standards for veterinary diagnostics through its Manual of Diagnostic Tests and Vaccines for Terrestrial Animals and its Manual of Diagnostic Tests for Aquatic Animals [12]. In addition, it maintains a register of WOAH-Approved Diagnostic Kits: a public list of validated, high-performing test kits that is currently undergoing revision and is expected to be fully updated by 2027 [13]. WOAH has also supported its Members in strengthening veterinary laboratories and surveillance systems, while at the same time promoting the harmonisation of diagnostic regulations across regions [11].

Complementing these efforts, WOAH partnered with Diagnostics for Animals (D4A) in 2024 to improve global access to quality veterinary diagnostics [14]. As part of this initiative, D4A is building the world’s first global database of veterinary diagnostic regulations, which currently includes information from 121 countries. This interactive mapping tool consolidates data on regulatory authorities, product categories, legal requirements and harmonisation efforts, thereby supporting manufacturers in compliance and strengthening the effectiveness of global disease control [15]. In Europe, the Committee for Standardization (CEN/TC 469) is collaborating with 34 countries to harmonise methodologies for tests such as the enzyme-linked immunosorbent assays (ELISA) and PCR, as well as data exchange [16]. Together, these initiatives aim to bring consistency and reliability to veterinary diagnostics and international trade, ensuring that when a disease emerges in one country, others can act rapidly and with confidence in the diagnostic tools available.

The health of animals, humans and the environment depends on the decisions we make today. Investing in veterinary diagnostics is not just a technical step, but the foundation of effective disease control. Both governments and the private sector have a role in strengthening this foundation, placing veterinary diagnostics at the heart of animal health. Key actions include funding and equipping veterinary diagnostic labs, making use of WOAH Reference Laboratories, adopting WOAH standards on test validation, and investing in research and development for affordable, field-adapted tools. Ensuring access to diagnostics in rural areas is particularly critical, as it allows outbreak responses and vaccination campaigns to be guided by reliable evidence rather than assumptions.

By placing veterinary diagnostics at the centre of One Health action plans, governments can safeguard public health, protect food systems, mitigate the spread of AMR, and enhance preparedness for biological threats. With greater investment in veterinary diagnostics, we can protect livelihoods, strengthen health systems and build a resilient future. The necessary tools already exist; with broader access, they could be decisive in preventing outbreaks from spreading out of control.

Main image: ©ChatGPT

References

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