Zoonotic Diseases

Primary reference(s)

WHO, FAO and OIE, 2019. Taking a Multisectoral, One Health Approach: a Tripartite Guide to Addressing Zoonotic Diseases in Countries. World Health Organization (WHO), Food and Agriculture Organization of the United Nations (FAO), World Organisation for Animal Health (WOAH). Accessed 26 May 2025.

WHO, 2020. Zoonoses Fact Sheet. World Health Organization (WHO). Accessed 26 May 2025.

Annotations

Key relevant UN convention / multilateral treaty

International Health Regulations (2005), 3rd ed. (WHO, 2016).

Quadripartite Memorandum of Understanding (MoU) signed for a new era of One Health collaboration 2022 (FAO, OiE, UNEP, & WHO, 2022)

Drivers

A zoonosis is an infectious disease that has jumped from a non-human animal to humans. Zoonotic pathogens may be bacterial, viral or parasitic, or may involve unconventional agents and can spread to humans through direct contact or through food, water or the environment. They represent a major public health problem around the world due to our close relationship with animals in agriculture, as companions and in the natural environment. Zoonoses can also cause disruptions in the production and trade of animal products for food and other uses (WHO, 2020).

Zoonoses comprise a large percentage of all newly identified infectious diseases as well as many existing ones. Some diseases, such as HIV, begin as a zoonosis but later mutate into human-only strains. Other zoonoses can cause recurring disease outbreaks, such as Ebola virus disease and salmonellosis. Still others, such as the novel coronavirus that causes COVID-19, have the potential to cause global pandemics (WHO, 2020).

Impacts

Antimicrobial resistance is a complicating factor in the control and prevention of zoonoses. The use of antibiotics in animals raised for food is widespread and increases the potential for drug-resistant strains of zoonotic pathogens capable of spreading quickly in animal and human populations (WHO, 2020). 

Markets selling the meat or by-products of wild animals are particularly high risk due to the large number of new or undocumented pathogens known to exist in some wild animal populations (WHO, 2020).

Multi-hazard context

Zoonoses comprise a large percentage of all newly identified infectious diseases as well as many existing ones. Some diseases, such as HIV, begin as a zoonosis but later mutate into human-only strains. Other zoonoses can cause recurring disease outbreaks, such as Ebola virus disease and salmonellosis. Still others, such as the novel coronavirus that causes COVID-19, have the potential to cause global pandemics (WHO, 2020).

Risk Management

Taking a multisectoral, One Health approach is necessary to address complex health threats at the human-animal-environment interface, such as rabies, zoonotic influenza, anthrax, and Rift Valley fever. Such zoonotic diseases continue to have major impacts on health, livelihoods, and economies, and cannot be effectively addressed by one sector alone (WHO, FAO, WOAH, 2019). 

The World Health Organization (WHO) in partnership with the United Nations Food and Agricultural Organization (FAO) and World Organisation for Animal Health (OIE), leads the development of global norms and standards for zoonotic diseases, as well as technical work on pathogen detection, risk assessment and management (WHO, FAO, OIE, 2019). 

On 17 March 2022. the four international agencies, the Food and Agriculture Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE), the UN Environment Programme (UNEP) and the World Health Organization (WHO), have signed a groundbreaking agreement to strengthen cooperation to sustainably balance and optimize the health of humans, animals, plants and the environment. The new Quadripartite MoU provides a legal and formal framework for the four organizations to tackle the challenges at the human, animal, plant and ecosystem interface using a more integrated and coordinated approach. This framework will also contribute to reinforcing national and regional health systems and services (FAO, OiE, UNEP, WHO, 2022) 

One Health is an integrated, unifying approach to balance and optimize the health of people, animals and ecosystems. It uses the close, interdependent links among these fields to create new surveillance and disease control methods. For example, the way land is used can impact the number of malaria cases. Weather patterns and human-built water controls can affect diseases like dengue. Trade in live, wild animals can increase the likelihood of infectious diseases jumping over to people (called disease spillover). 

Gaps in One Health knowledge, prevention and integrated approaches were seen as key drivers of the pandemic. By addressing the linkages between human, animal and environmental health, One Health is seen as a transformative approach to improved global health. One Health applies to a range of issues, including:   

• antimicrobial resistance (AMR), which happens when germs like bacteria and parasites develop the ability to defeat the drugs designed to kill them and continue growing and spreading; 
• zoonotic diseases, which are infectious diseases that are caused by germs that spread between animals and people, such as Ebola, avian influenza, rabies, etc.;  
• vector-borne diseases, which affect people who get bitten by a vector (mosquitoes, ticks, lice and fleas) and include dengue fever, West Nile virus, Lyme disease and malaria;  
• food safety and foodborne diseases, caused by contamination of food and occur at any stage of the food production, delivery and consumption chain, such as norovirus, salmonella, listeria, etc.; and  
• environmental health, such as water pollution, air pollution and climate change.   

Collaboration across sectors and disciplines through a One Health approach is a vital solution for addressing the complex health challenges facing our society. To prevent, detect and respond to emerging health challenges, all relevant sectors must collaborate in an integrated manner to achieve together what no sector can achieve alone. 

Prevention methods for zoonotic diseases differ for each pathogen; however, several practices are recognised as effective in reducing risk at the community and personal levels including safe animal husbandry, increased hygiene measures and standards for clean drinking water and waste removal. Some zoonoses, such as rabies, are 100% preventable through vaccination and other methods (WHO, 2020). 

As part of the One Health approach, the WHO collaborates with the FA) and the WOAH on the Global Early Warning System for Major Animal Diseases GLEWS). This joint system builds on the added value of combining and coordinating alert mechanisms of the three agencies to assist in early warning, prevention and control of animal disease threats, including zoonoses, through data sharing and risk assessment (WHO, 2020).

Monitoring

The section and the table below offer an overview of monitoring for zoonotic diseases. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.

WHO supports countries to conduct all-hazards strategic risk assessment in the contexts of health emergencies and disasters, which results in the development of a country risk profile. Empowered with the country risk profile, inclusive of a seasonal risk calendar, countries can anticipate potential emergencies before they occur to trigger early alerts and inform early actions (WHO, 2021).

WHO's Early Warning, Alert and Response System (EWARS) has been designed to improve disease outbreak detection in emergency settings, such as in countries in conflict or following a disaster from natural hazards. It is a simple and cost-effective way to rapidly set up a disease surveillance system. EWARS is deployed during an emergency as an adjunct to the national disease surveillance system. WHO works with Ministries of Health and health sector partners to train local health workers to use the system. After the emergency, EWARS should re-integrate back into the national system (WHO, 2023).