The COVID-19 pandemic is the most recent infectious disease outbreak to emerge at the human-animal-environment interface, but it is not the first time an unknown or new virus has developed from close contact between humans and wildlife. The severe acute respiratory syndrome (SARS) pandemic in 2002-2003, for example, was traced to human interaction with civets that had been infected by bats.1 The Centers for Disease Control and Prevention estimates that 75% of new or emerging infectious diseases originate from animals.2

Although the precise origin of SARS-CoV-2 has not yet been determined, it was first identified in December 2019 in Wuhan, China, and linked to a seafood and live animal market.3 This wet market sells wild animals such as live poultry, pigs, and exotic animals, creating a hot spot for zoonotic transmission. The genetic profile of the SARS-CoV-2 coronavirus closely matches a coronavirus isolated from bats, the probable natural host.4 A spillover event likely occurred when the bat coronavirus mutated and jumped to an intermediate animal host before mutating again and transmitting to humans. The suspected intermediate animal host is the pangolin, an endangered, exotic animal that is trafficked illegally.5 It will be critical to obtain evidence to definitively determine the natural and intermediate hosts of SARS-CoV-2, as well as the risk factors that allowed the virus to jump to humans.

Understanding the risk factors and origins of infectious disease outbreaks helps us pinpoint how, why, and where they occur to prevent future outbreaks. Determining which animals are moving into new geographical areas and which wildlife are consumed and sold is also important. The scientific community is getting better at detecting viruses; however, only a small number of the world's viruses are known. Once there is evidence about the profiles of viruses, particularly those circulating in animals that are at a high risk to jump to humans, vaccines and test kits for the first emerging cases can be more rapidly produced.

Humans are creating conditions for threats such as SARS-CoV-2 to develop and thrive. Anthropogenic changes, including globalization, climate change, population growth, destruction of habitats, and interaction with and trade of wildlife, are significant drivers for infectious disease outbreaks and present a hidden cost of economic development.6 For example, the destruction of forests for agriculture brings humans in closer contact with certain animals. More people are moving into cities, which provide new homes for wildlife with increased access to food compared with life in the wild. Pandemics have been dominated by zoonotic pathogens, and their emergence correlates strongly with human density and biodiversity.7

Novel coronaviruses such as SARS-CoV-2 will continue to emerge due to our increased interaction with certain host species. Although COVID-19 highlights increased human-animal interaction and the destruction of our environment as major drivers for new pandemics, we continue to separate human health from ecosystem and animal health.

One Health is a multisectoral, interdisciplinary, and collaborative approach to attain optimal health for animals, the environment, and humans.8 There is a pressing need for increased communication and collaboration between professionals such as doctors, veterinarians, and social scientists, and this is where building capacity in One Health would be beneficial across disciplines. The best available evidence from different fields needs to be collected and shared, which is a framework that One Health provides. Increased funding from governments and foundations must be prioritized to support interdisciplinary professional development and research. The One Health approach also considers the cultural components of pandemics. For example, wildlife trade for traditional medicine and food is common in many cultures. It is important to incorporate anthropologists and social scientists when designing and implementing policies for wildlife trade and consumption in order for these policies to be effective and sustainable.

There has been some movement operationalizing One Health globally with international organizations including the Food and Agriculture Organization, the World Organisation for Animal Health, and the World Health Organization. These organizations signed an agreement in 2008 to share the coordination of activities that investigate and address health risks at the human-animal-environment interface, and developed a strategic framework that contributed to the management of the 2008 H5N1 influenza virus pandemic.9

In response to emerging infectious disease threats such as the Rift Valley fever, the Centers for Disease Control in Kenya and the Kenyan government established a One Health program that demonstrated increased surveillance in animals and improved investigations of outbreaks.10 Case studies conducted in Nigeria, Uganda, and Tanzania on using a One Health approach to health policy demonstrated successful control of neglected tropical and infectious diseases; however, challenges of sustainability and operationalization remain.11

Responses to pandemics continue to be tackled as isolated events and not as a reflection of a larger problem. Exacerbated by the changing environment, the increase in novel pathogens suspected to have emerged from wildlife, such as SARS-CoV-2, is a symptom of a deteriorating world. A paradigm shift is needed in how we think about and act on health. One Health provides a framework for us, and it is time to widely promote and adopt its message of connectivity.12

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