One Health Initiative: Veterinary Medicine's Role in Human and Environmental Health

The One Health Initiative is a globally recognized framework that treats human health, animal health, and environmental health as interdependent systems requiring coordinated scientific and policy responses. This page covers the definition and scope of One Health as it applies to veterinary medicine in the United States, the mechanisms through which veterinary professionals participate, the common scenarios where that participation is most consequential, and the decision boundaries that distinguish veterinary from medical or environmental agency jurisdiction. Understanding this framework clarifies why zoonotic diseases and the public health veterinary role cannot be managed effectively through human medicine alone.

Definition and scope

The One Health concept, formally described by the American Veterinary Medical Association (AVMA) and endorsed by the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO), and the World Organisation for Animal Health (WOAH, formerly OIE), holds that approximately 60 percent of known infectious diseases in humans are zoonotic in origin (CDC One Health). That figure, drawn from CDC epidemiological framing, establishes the quantitative basis for treating veterinary surveillance as a frontline public health function rather than a parallel or subordinate discipline.

In the United States, the Centers for Disease Control and Prevention houses a dedicated One Health Office that coordinates across federal agencies including the U.S. Department of Agriculture (USDA Animal and Plant Health Inspection Service, APHIS), the Food and Drug Administration (FDA), and the Environmental Protection Agency (EPA). Each agency retains distinct statutory authority, but surveillance data, outbreak investigation protocols, and antimicrobial resistance monitoring are designed to flow across agency lines.

Scope boundaries are explicit: One Health does not merge regulatory authority. Veterinary licensure operates under state law, as administered by individual state veterinary medical boards working within frameworks like those described at AVMA and veterinary licensing requirements. Human medical licensure remains under separate state medical board authority. The One Health framework governs information-sharing, joint surveillance, and collaborative research policy — not clinical practice jurisdiction.

How it works

Operationally, One Health functions through four discrete coordination layers:

  1. Surveillance integration — Veterinary diagnostic laboratories submit pathogen data to the National Animal Health Laboratory Network (NAHLN), operated under USDA APHIS. That data feeds into CDC's National Notifiable Disease Surveillance System (NNDSS) when zoonotic pathogens are detected. Veterinary laboratory and diagnostic services form the primary data-entry point for this system.

  2. Outbreak investigation — When a cluster of human illness has a suspected animal reservoir, CDC's Epidemic Intelligence Officers coordinate with USDA APHIS and state veterinary authorities. The 2022 H5N1 highly pathogenic avian influenza (HPAI) outbreak, which by April 2024 had been confirmed in dairy cattle herds across 9 U.S. states (USDA APHIS HPAI Detections), illustrated this coordination: veterinary field teams, federal animal health officials, and human epidemiologists operated under a unified incident command structure.

  3. Antimicrobial resistance (AMR) monitoring — The FDA's National Antimicrobial Resistance Monitoring System (NARMS) tracks resistance patterns across human clinical isolates, retail meat samples, and animal isolates. Veterinary prescribing practices for antibiotics classified as medically important fall under FDA Guidance for Industry 152 and 209, which restrict certain antibiotic uses in food-producing animals without veterinary oversight.

  4. Environmental health linkage — Wildlife surveillance conducted by the U.S. Geological Survey (USGS) National Wildlife Health Center interfaces with both veterinary and public health agencies. Toxicological findings in wildlife populations — such as lead poisoning in raptors or PFAS contamination in fish-eating bird colonies — feed environmental risk assessments that inform both EPA regulatory actions and veterinary clinical alerts.

Common scenarios

The One Health framework is most operationally visible in four categories of scenarios:

Zoonotic disease emergence — Novel or re-emerging pathogens with animal reservoirs, including influenza A variants, monkeypox (mpox), and Salmonella serotypes linked to backyard poultry, trigger joint federal-state investigation protocols. Veterinary practitioners are legally required in most states to report specific zoonotic diseases to state animal health officials; those reports propagate upward to USDA APHIS and potentially to CDC.

Food safety and foodborne illness — Veterinarians working in livestock and farm animal veterinary services are embedded within food production systems that FDA and USDA Food Safety and Inspection Service (FSIS) regulate. Antemortem and postmortem inspection by USDA-accredited veterinarians is a statutory food safety mechanism, not an advisory function.

Antimicrobial stewardship in food animals — Following FDA's Veterinary Feed Directive (VFD) rule (21 CFR Part 558), medically important antibiotics in animal feed require a licensed veterinarian's written authorization. This places veterinary decision-making at the regulatory boundary between agricultural practice and human antibiotic resistance outcomes.

Wildlife and exotic animal interfaces — Exotic and zoo animal veterinary care practitioners frequently interact with USDC Fish and Wildlife Service (FWS) permit requirements and CDC import regulations for specific species. Wildlife-to-domestic-animal-to-human pathogen spillover events, such as the 2003 monkeypox outbreak traced to imported Gambian pouched rats, demonstrate the regulatory and clinical complexity at this interface.

Decision boundaries

One Health creates coordination obligations but does not override existing regulatory jurisdiction. The following distinctions govern practical application:

Veterinary vs. medical jurisdiction — A licensed veterinarian diagnoses and treats animals. When a zoonotic pathogen is suspected in a human patient, the reporting and treatment authority shifts entirely to licensed human healthcare providers and state public health departments. Veterinary findings can inform human clinical investigations but do not authorize human medical recommendations.

Federal vs. state authority — USDA APHIS and FDA hold federal authority over interstate commerce, import/export, and food production. State veterinary boards and state departments of agriculture govern intrastate practice and locally notifiable diseases. These jurisdictions can overlap, as seen in brucellosis control programs that require both state-issued quarantine authority and federal indemnification protocols.

Surveillance vs. clinical care — One Health surveillance obligations (notifiable disease reporting, laboratory submission to NAHLN) are distinct from clinical care decisions. A veterinarian managing a sick animal follows clinical standards of care — described in the context of veterinary preventive care and wellness — regardless of whether a parallel public health investigation is active.

Comparative risk classification — WHO and OIE classify animal pathogens by zoonotic risk tier. Tier 1 agents (e.g., rabies, anthrax, highly pathogenic avian influenza) trigger mandatory federal notification. Lower-tier pathogens may require state-level reporting only. Veterinary practitioners must know their state's specific notifiable disease list, which varies from the federal list maintained by USDA APHIS.

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