ONE HEALTH - Action Track 2

Reducing the risks from emerging and re-emerging zoonotic epidemics and pandemics

ONE HEALTH: A Comprehensive Approach for Addressing Health Threats at the Human-Animal-Environment Interface

One Health

Action Track 2, titled “Reducing the risks from emerging and re-emerging zoonotic epidemics and pandemics,” is an integral component of the efforts by PAHO, Member States, and international partners to enhance surveillance, preparedness, and response to pathogens with epidemic and pandemic potential. As most of these pathogens have an animal reservoir and vector, these efforts must be conducted at the human-animal-environmental interface.

The Region of the Americas is at great risk for the emergence and reemergence of zoonotic pathogens. The ecologically diverse Amazon basin and Darien Gap harbor a myriad of potentially emerging pathogens, with animals as possible reservoirs and vectors. The spillover risk to human populations is ever-increasing because of factors such as the encroachment of human settlements in sylvatic areas, unplanned urbanization, and the potential impact of climate change and more frequent extreme weather events. For instance, epizootic spread of the yellow fever virus reached during 2016–2019 the southeast coast of Brazil for the first time, causing spillover human infections in densely populated areas. The investigation of a hemorrhagic fever cluster in Bolivia in 2019 eventually revealed the reservoir of the etiological pathogen (Chapare virus) in an autochthonous rodent species, with which rural workers come in contact. Avian influenza A(H5N1) virus has been spreading since 2014 in the Americas in wild birds as well as farm and domestic poultry. As of January 2024, spillover infections have been reported in wildlife mammals in six countries (e.g., red foxes and skunks in North America, and fur seals in South America), and three human cases have been identified between April 2022 and March 2023 in the United States, Ecuador, and Chile, respectively.

Along the human-animal-environmental interface, PAHO works together with Member States and international partners to develop and implement preparedness and response plans, epidemiologic/virologic/genomic surveillance systems, laboratory diagnostic and reference services and their networking, biosafety and biosecurity, and capacities on clinical management and infection prevention and control. In addition, PAHO forecasts and characterizes infection and disease risks, including in potential animal and wildlife reservoirs, and develops evidence-based strategies to predict, prevent, detect, and respond to zoonotic hazards. All these actions are also achieved through expert networks to leverage international expertise and to foster regional knowledge-sharing and collaboration, as well as by providing secretariat support to regional and global initiatives.


Best practices

Courses on the PAHO Virtual Campus


Course on respiratory protection in health-care settings, 2024 (upcoming)

Guidelines, Norms, Relevant Publications and Support Documents Related to Action Track 2