THIS article offers a concise introduction to the One Health approach in addressing zoonotic outbreaks. The fundamental principles of One Health focus on zoonoses, which are infectious diseases originating from animals that can spread to humans. A zoonotic outbreak occurs when these diseases begin to spread widely among humans. Examples of such outbreaks include deadly diseases like rabies or rapidly spreading airborne infections such as SARS or bird flu, which significantly impact human health and the economy.
As human interaction with animal populations intensifies due to factors like increased travel, animal husbandry, and habitat destruction, the likelihood of significant zoonotic outbreaks is expected to rise. To mitigate these risks, it’s crucial to understand how zoonotic diseases are transmitted and amplified among wild and domestic animals and between these animal populations. It’s also vital to consider how these diseases can be transmitted between animals and humans, either through direct contact or via vectors like mosquitoes, flies and ticks.
Some zoonotic outbreaks can spread rapidly, as evidenced by the COVID-19 pandemic, which demonstrated how quickly an outbreak can escalate into a global crisis, affecting individuals, societies and the world at large. To fully understand zoonotic outbreaks, it’s essential to examine not just the human aspect but also the animal and environmental sectors, and to coordinate interventions across these areas.
One Health is a holistic approach that connects the health of humans, animals and the environment. To illustrate this, consider the introduction of a new influenza A virus, like H5N1, brought into a country by migratory birds. These birds might contaminate the environment around farms with their droppings or come into direct contact with domestic or farm animals, leading to large outbreaks among poultry. This can then spread to farmers, their families, and others in society. The infected animals might also contaminate the environment, such as at slaughterhouses or live animal markets, leading to further transmission to other animals or humans.
This article aims to provide a foundational understanding of the One Health concept, which will be explored further in subsequent articles to examine how the human and animal health sectors coordinate their efforts using this approach. Coordination across sectors is essential to ensure that all efforts are effective and well-timed. With this example in mind, let’s delve deeper into how zoonotic outbreaks may develop over time. You might already know that One Health identifies four distinct phases in preparing for and responding to zoonotic outbreaks: preparedness, alert, response, and recovery.
The first phase is preparedness, during which there are no signs of an outbreak yet, but risk factors are increasing, and the likelihood of an outbreak is high. This phase involves getting processes and resources ready for the subsequent phases. This includes bringing together everyone needed to monitor, assess, and respond to potential outbreaks and contribute to recovery efforts.
The second phase is the alert phase, triggered when suggestive clinical cases are reported in animals or humans. During this phase, it’s crucial to have systems in place to detect potential outbreaks by collecting and analyzing data continuously. This involves surveillance of communicable diseases and looking for signals of infection spillover from one population to another, which could be due to changes in migration patterns, vector populations, or human behavior. If spillover occurs between wild and domestic animal populations and is followed by sufficient transmission, the outbreak is confirmed, and we move to the third phase: response. The goal in the response phase is to interrupt transmission and control the epidemic, returning the situation to normal.
The fourth and final phase is recovery, which begins after the outbreak is over. This phase involves helping affected populations recover and learning lessons from the outbreak to improve future responses.
—The writer is contributing columnist.
