ZOONOSES

ONE WORLD, ONE HEALTH: PREVENT ZOONOSES

August 5, 2024

ONE WORLD, ONE HEALTH: PREVENT ZOONOSES

Swagat Patnaik^1*

^{2ND PROFESSIONAL YUEAR STUDENT.INSTITUTE OF VETERINARY SCIENCE & ANIMAL HUSBANDRY,SOA DU}

^1*Siksha ‘O’ Anusandhan, Bhubaneshwar-751003

Introduction :-

In an increasingly interconnected world, the health of humans, animals, and the environment are deeply intertwined. This interconnectedness is encapsulated in the concept of “One Health,” which recognizes that the health of people is connected to the health of animals and our shared environment. One of the most pressing issues that highlight the necessity of this approach is the prevention of zoonoses—diseases that are transmitted from animals to humans.Zoonotic diseases have been responsible for some of the most significant public health crises in recent history. The COVID-19 pandemic, which has claimed millions of lives and disrupted global economies, is a stark reminder of the devastating impact of zoonotic diseases. Other notable zoonotic diseases, such as Ebola, avian influenza, and rabies, have similarly demonstrated the urgent need for comprehensive strategies to prevent and manage these infections.The One Health approach offers a holistic and collaborative framework to address the complex challenges posed by zoonoses. By fostering interdisciplinary collaboration among veterinarians, physicians, ecologists, and other experts, One Health aims to enhance our ability to predict, prevent, and respond to zoonotic threats. This article explores the concept of One Health in the context of zoonosis prevention, highlighting the importance of integrated efforts to safeguard global health.As we delve deeper into the subject, we will examine the various aspects of zoonotic diseases, the principles of the One Health approach, and practical measures to prevent zoonoses. Through case studies and analysis of current challenges and opportunities, we will illustrate the critical need for a unified global response to zoonotic threats. By understanding and implementing the One Health principles, we can build a more resilient world, better prepared to prevent and mitigate the impact of zoonotic diseases.

Understanding Zoonoses:-

Definition and Example :-Zoonoses are diseases that are naturally transmitted between animals and humans. These diseases can be caused by a range of pathogens including bacteria, viruses, parasites, and fungi. Common examples of zoonotic diseases include rabies, caused by the rabies virus; salmonellosis, caused by Salmonella bacteria; and Lyme disease, caused by the bacterium Borrelia burgdorferi.

Historical Perspective:-Zoonotic diseases have been part of human history for millennia. The Black Death, which killed an estimated 25 million people in the 14th century, was caused by the bacterium Yersinia pestis, which is transmitted by fleas that infest rodents. More recently, the 2009 H1N1 influenza pandemic, commonly known as swine flu, originated from a reassortment of bird, swine, and human flu viruses.

Impact on Human Health:-The impact of zoonotic diseases on human health is profound. Zoonoses can lead to significant morbidity and mortality, strain healthcare systems, and disrupt economies. The COVID-19 pandemic is a stark example of how a zoonotic disease can cause widespread devastation. In addition to the direct health impacts, zoonotic diseases can also have social and economic consequences, including loss of livelihoods, disruption of trade, and increased healthcare costs.

Background:-

One Health System emerged when Rudolf Virchow (1821-1902) placed veterinary medicine in the field of human health in the 19th century and claimed that there was no distinction between the two. This was followed by the global rise of the One Health Strategy and the revolution of the early 2000s; since then, collaborative efforts have continued to expand .The commitment to providing a good link between all ecosystem types goes back to when a conference was held in Manhattan (New York, USA) in 2004 with the participation of experts from many disciplines from around the world to discuss the problems

caused by the spread of human diseases, livestock and wildlife.Then, in 2008, four international organizations, including the Food and Agriculture Organization of the United Nations (FAO), the World Health Organization (OIE), the World Health Organization (WHO), and UNICEF, together with the World Bank and the United Nations Influenza System Coordinator, produced a policy report entitled “One World, One Health: Safety for Safety. system Interface” The World Veterinary Medical Association (WVA) and World Medical Association (WMA) World Health Conference in May 2015 is one of the most important for expanding the United Health platform, proposing a collaborative partnership between veterinarians and doctors to improve animal and human health. Since then, the concept of United Health has gained recognition and its initiatives have grown faster than the platform

ETIOLOGY OF ZOONOSES :-

The aetiology of zoonoses refers to the various microorganisms that can cause these infectious diseases. Zoonotic diseases can be caused by different types of pathogens, including bacteria, viruses, parasites, and fungi. Here’s an overview of the aetiology of zoonoses:

Bacterial Zoonoses:

Salmonella: Salmonella species, such as Salmonella enterica, can cause foodborne zoonotic infections. Contaminated food products, especially poultry, eggs, and unpasteurized dairy products, are common sources of infection.

Brucella: Brucella species, including Brucella abortus and Brucella melitensis, can cause brucellosis, a bacterial infection primarily transmitted through contact with infected animals or their products (e.g., raw milk, unpasteurized cheese).

Escherichia coli (E. coli): Certain strains of E. coli, such as Shiga toxin-producing E. coli (STEC), can cause severe foodborne illnesses. Contaminated meat, dairy products, and fresh produce are common sources of infection.

Viral Zoonoses:

Influenza: Influenza viruses, including avian influenza viruses (e.g., H5N1, H7N9) and swine influenza viruses, can be transmitted from animals to humans. Direct contact with infected animals or their secretions/excretions is the primary route of transmission.

Rabies: Rabies is caused by lyssa viruses, which are primarily transmitted through the bite or scratch of an infected animal, most commonly dogs, bats, and wildlife.

Hendra and Nipah Viruses: These viruses, belonging to the Paramyxoviridae family, are associated with severe respiratory and neurological diseases. Fruit bats (also known as flying foxes) are considered natural reservoirs, and transmission to humans can occur through contact with contaminated fluids or tissues of infected animals.

Parasitic Zoonoses:

Toxoplasmosis: Toxoplasma gondii, a protozoan parasite, can cause toxoplasmosis. Infection can occur through the ingestion of undercooked meat containing tissue cysts or exposure to cat faeces.

Leishmaniasis: Leishmania parasites, transmitted through the bite of infected sandflies, can cause various forms of leishmaniasis in humans and animals.

Taeniasis/Cysticercosis: Taenia solium, a tapeworm, can cause taeniasis (intestinal infection) in humans. The larval form, cysticercosis, can develop in various tissues, including the brain and muscles, when humans ingest eggs through contaminated food or water

TRANSMISSION OF ZOONOTIC DISEASES: –

Zoonotic diseases can be transmitted through various routes, depending on the type of pathogen and the specific disease. Here are the primary modes of transmission for different types of zoonotic diseases:

Direct Contact:

Rabies: Transmitted through the bite or scratch of an infected animal, usually a mammal-like dog, bat, or raccoon.

Brucellosis: Contracted through direct contact with infected animals, their bodily fluids (e.g., blood, milk, urine), or tissues and commonly associated with livestock such as cattle, goats, and sheep.

Vector-Borne Transmission:

Lyme disease: Transmitted through the bite of infected black-legged ticks carrying the bacterium Borrelia burgdorferi.

Malaria: Transmitted through the bite of infected female Anopheles mosquitoes carrying the Plasmodium parasite.

West Nile fever: Spread through the bite of infected mosquitoes, primarily Culex species, carrying the West Nile virus.

Foodborne Transmission:

Salmonellosis: Acquired through consuming contaminated food products, particularly raw or undercooked eggs, poultry, meat, or dairy.

Campylobacteriosis: Usually associated with consuming undercooked poultry, unpasteurized milk, or contaminated water.

coli infections: Ingesting contaminated food or water, especially undercooked ground beef, raw vegetables, or unpasteurized dairy products.

Waterborne Transmission:

Leptospirosis: Contracted by coming into contact with water, soil, or food contaminated with the urine of infected animals, especially rodents.

Cryptosporidiosis: Caused by ingesting water or food contaminated with the Cryptosporidium parasite, often found in recreational water sources or livestock faeces.

Airborne Transmission:

Tuberculosis (TB): Can be transmitted through inhalation of respiratory droplets containing the bacteria Mycobacterium tuberculosis, usually from infected humans but also from animals like cattle.

Avian Influenza: Primarily spread through inhalation of respiratory droplets or direct contact with infected birds, particularly poultry.

It is important to note that these are just a few examples, and there are numerous other zoonotic diseases with unique modes of transmission. Additionally, some zoonotic diseases can have multiple transmission routes, further highlighting the complexity of these diseases and the need for comprehensive prevention and control measures.

PATHOGENESIS OF ZOONOTIC DISEASES: –

Zoonoses are diseases that can be transmitted from animals to humans. The pathogenesis, or the process by which these diseases develop and spread within the human body, can vary depending on the specific zoonotic agent involved. However, there are some general patterns and mechanisms that are commonly seen in the pathogenesis of zoonotic diseases. Here’s an overview of the pathogenesis of zoonoses:

Transmission: Zoonotic diseases are typically transmitted to humans through direct or indirect contact with infected animals or their products. Direct transmission can occur through bites, scratches, or close contact with bodily fluids or tissues of infected animals. Indirect transmission can occur through exposure to contaminated environments, such as consuming contaminated food or water, or through the bites of arthropod vectors like mosquitoes or ticks.

Entry and colonization: Once the zoonotic agent enters the human body, it needs to establish a foothold and start replicating. This often involves the pathogen overcoming various barriers, such as the skin, respiratory tract, gastrointestinal tract, or mucous membranes. Different zoonotic agents have evolved different strategies to breach these barriers and colonize specific tissues or organs.

Replication and dissemination: Zoonotic pathogens then replicate within the human host, often leading to localized or systemic infection. The pathogen may target specific cells or tissues, depending on its tropism. During replication, the pathogen may produce toxins or induce an inflammatory response, which can contribute to the development of symptoms.

Immune response: The human immune system recognizes the presence of the zoonotic pathogen and mounts a response to control and eliminate the infection. The immune response can involve both innate and adaptive mechanisms, including the activation of various immune cells, production of antibodies, and release of cytokines. The outcome of the immune response can vary, ranging from complete clearance of the pathogen to chronic infection.

Pathological effects: Zoonotic diseases can cause a wide range of pathological effects in humans. These effects can be direct, resulting from the action of the pathogen itself, or indirect, resulting from the immune response mounted against the pathogen. Examples of direct effects include tissue damage caused by viral replication or the production of bacterial toxins. Indirect effects can include inflammation, immunopathology, or autoimmune responses triggered by the immune system’s reaction to the infection.

Transmission to others: Zoonotic diseases can be contagious and spread from person to person, leading to outbreaks or epidemics. Transmission between humans can occur through various routes, including direct contact, respiratory droplets, or contaminated objects. Some zoonotic diseases, such as influenza or COVID-19, are highly transmissible among humans, while others have limited human-to-human transmission

HOW ZOONOSES AFFECT HUMAN HEALTH AND SOCIETY: –

Zoonoses, which are diseases transmitted from animals to humans, can have significant harmful effects on the human world. Here are some ways in which zoonoses can negatively impact human health and society:

Public Health Impact: Zoonotic diseases can cause widespread illness and potentially lead to public health emergencies. Outbreaks and pandemics caused by zoonoses can result in high numbers of infections, hospitalizations, and deaths, leading to significant social and economic burdens.

Mortality and Morbidity: Zoonoses can cause severe illness and have high mortality rates. Diseases like rabies, Ebola, and highly pathogenic avian influenza (e.g., H5N1) have been associated with high fatality rates, leading to loss of human lives and devastating impacts on affected communities.

Economic Losses: Zoonotic diseases can have substantial economic consequences. Outbreaks can disrupt trade and commerce, impact tourism, and lead to loss of productivity due to illness, hospitalization, and death. Costs associated with disease surveillance, treatment, control measures, and public health interventions can be substantial.

Impact on Livelihoods: Zoonotic diseases can directly affect people’s livelihoods, especially those involved in agriculture, livestock farming, and wildlife-related industries. Outbreaks can result in trade restrictions, loss of livestock, reduced productivity, and loss of income for farmers and other stakeholders in the food production chain.

Social Disruption: Zoonotic disease outbreaks can cause fear, panic, and social disruption. Public health measures such as quarantine, travel restrictions, and social distancing can impact daily life, disrupt social activities, and strain social and community relationships.

Environmental Consequences: Zoonotic diseases often have environmental factors associated with their emergence and transmission. Factors such as deforestation, habitat destruction, and climate change can contribute to the spillover of pathogens from animals to humans. Addressing zoonoses requires considering the impact of human activities on ecosystems and the environment.

Antimicrobial Resistance: Some zoonotic diseases are treated with antimicrobial drugs. However, misuse and overuse of antibiotics in both human and animal health can contribute to the development of antimicrobial resistance. This can lead to treatment failures and make infections more difficult to manage, posing a threat to public health.

Addressing zoonotic diseases requires a comprehensive and interdisciplinary approach that includes surveillance, prevention, control measures, and global cooperation. The One Health approach, which recognizes the interconnection between human, animal, and environmental health, is crucial in combating zoonoses and minimizing their harmful effects on the human world. By investing in research, strengthening healthcare systems, improving hygiene practices, promoting responsible antimicrobial use, and implementing effective preventive measures, we can mitigate the impact of zoonotic diseases and protect human health

The One Health Approach:-

Concept and Principles

The One Health approach is based on the recognition that the health of humans, animals, and the environment are interconnected. It promotes a collaborative, multi-disciplinary approach to achieve optimal health outcomes. Key principles of One Health include:

– Interdisciplinary collaboration among human health, animal health, and environmental health professionals.

– Integrated surveillance and response systems.

– Prevention and control measures that address the root causes of health issues.

– Community engagement and education to promote health and prevent disease.

Importance of Interdisciplinary Collaboration

Interdisciplinary collaboration is at the heart of the One Health approach. By bringing together experts from different fields, One Health facilitates the sharing of knowledge and resources, enhances disease surveillance and response, and promotes the development of comprehensive strategies to prevent and control zoonotic diseases. For example, veterinarians, physicians, and ecologists can work together to identify the sources of zoonotic infections, understand their transmission dynamics, and implement effective prevention and control measures.

Case Studies of Successful One Health Initiatives

Several successful One Health initiatives have demonstrated the value of this approach in preventing and controlling zoonotic diseases. For instance, the PREDICT project, funded by the United States Agency for International Development (USAID), has been instrumental in identifying and monitoring zoonotic pathogens in wildlife populations. Similarly, the Global Early Warning System (GLEWS), a joint initiative of the World Health Organization (WHO), the Food and Agriculture Organization (FAO), and the World Organisation for Animal Health (OIE), aims to improve the detection and response to zoonotic diseases.

Preventing Zoonotic Diseases

Surveillance and Early Detection

Effective surveillance and early detection are critical for preventing zoonotic diseases. This involves monitoring animal populations for signs of illness, conducting regular testing and screening, and implementing rapid response measures when a potential zoonotic threat is identified. Advanced technologies, such as genomic sequencing and data analytics, can enhance our ability to detect and respond to emerging zoonotic pathogens.

Vaccination and Treatment

Vaccination is a key strategy for preventing zoonotic diseases. Vaccines can protect both animals and humans from infections, reducing the risk of transmission. For example, rabies vaccination programs for dogs have been highly successful in reducing human cases of rabies. In addition to vaccination, timely and effective treatment of infected individuals can help to control the spread of zoonotic diseases.

Environmental Management

Environmental management plays a crucial role in preventing zoonotic diseases. This includes measures to reduce contact between humans and wildlife, such as habitat conservation and restoration, as well as improving sanitation and waste management practices. Reducing environmental contamination and improving biosecurity in agricultural settings can also help to prevent the spread of zoonotic pathogens.

Education and Awareness

Education and awareness are essential components of zoonotic disease prevention. Public health campaigns can inform communities about the risks of zoonotic diseases and promote behaviors that reduce the risk of infection. Training programs for healthcare professionals, veterinarians, and other stakeholders can enhance their capacity to identify and respond to zoonotic threats.

Challenges and Opportunities

Global and Local Challenges

Preventing zoonotic diseases presents several challenges, both at the global and local levels. These include limited resources and infrastructure, particularly in low- and middle-income countries, as well as gaps in knowledge and data on zoonotic pathogens and their transmission. Political and socio-economic factors can also influence the effectiveness of zoonotic disease prevention and control efforts.

Technological Advancements

Technological advancements offer new opportunities for preventing and controlling zoonotic diseases. Innovations in diagnostics, vaccines, and therapeutics can enhance our ability to detect, prevent, and treat zoonotic infections. Additionally, digital technologies and data analytics can improve disease surveillance and early warning systems, enabling more rapid and effective responses to emerging zoonotic threats.

Policy and Governance

Effective policy and governance are critical for the successful implementation of One Health approaches to zoonotic disease prevention. This includes the development of policies and regulations that promote interdisciplinary collaboration, support research and innovation, and ensure adequate funding and resources for zoonotic disease prevention and control efforts. Strong leadership and coordination at the national and international levels are also essential for addressing the complex challenges posed by zoonotic diseases.

Case Studies

COVID-19

The COVID-19 pandemic has underscored the importance of a One Health approach to zoonotic disease prevention. The virus responsible for COVID-19, SARS-CoV-2, is believed to have originated in bats and potentially transmitted to humans through an intermediate animal host. The pandemic has highlighted the need for enhanced surveillance of wildlife populations, improved biosecurity in markets and agricultural settings, and greater international collaboration to prevent and respond to zoonotic threats.

Ebola

Ebola virus disease is another example of a zoonotic disease with significant public health implications. The virus is thought to be transmitted to humans through contact with infected animals, such as fruit bats or primates. Outbreaks of Ebola have demonstrated the importance of early detection and rapid response, as well as the need for community engagement and education to prevent the spread of the virus.

Avian Influenza

Avian influenza, or bird flu, is caused by influenza viruses that primarily infect birds but can also infect humans. The emergence of highly pathogenic avian influenza strains, such as H5N1, has raised concerns about the potential for a pandemic. Control measures, such as culling infected poultry, vaccination, and surveillance of bird populations, are critical for preventing the spread of avian influenza and reducing the risk of human infection.

Future Directions

Innovations in Disease Prevention

Innovations in disease prevention, such as new vaccines, diagnostics, and therapeutics, hold promise for improving our ability to prevent and control zoonotic diseases. Advances in genomic technologies and bioinformatics can enhance our understanding of zoonotic pathogens and their transmission dynamics, enabling the development of more effective prevention and control strategies.

Strengthening Global Health Systems

Strengthening global health systems is essential for improving our ability to prevent and respond to zoonotic diseases. This includes building capacity for disease surveillance and response, improving healthcare infrastructure, and ensuring equitable access to healthcare services. International cooperation and coordination are also crucial for addressing the global nature of zoonotic threats.

Community Engagement

Community engagement is a key component of successful zoonotic disease prevention and control efforts. By involving communities in the planning and implementation of prevention measures, we can enhance their understanding of zoonotic risks and promote behaviors that reduce the risk of infection. Community-based approaches can also help to build trust and ensure that prevention measures are culturally appropriate and effective.

CAN HUMAN DISEASES TRANSFER TO ANIMALS?

Yes, human diseases can sometimes transfer to animals, resulting in what is known as reverse zoonosis or anthroponomic. In these cases, a disease that primarily affects humans can be transmitted to animals, leading to infections in animal populations. The transfer of human diseases to animals can occur through various mechanisms, including direct contact with infected individuals, exposure to contaminated environments, consumption of contaminated food or water, or through vectors such as mosquitoes or ticks.

There have been several documented cases of reverse zoonosis. For example, tuberculosis, caused by the bacterium Mycobacterium tuberculosis, can be transmitted from humans to animals, including primates, elephants, and lions. Influenza viruses, such as the H1N1 influenza virus, have also been transmitted from humans to various animal species, including pigs, cats, dogs, and even tigers in captivity. When a human disease transfers to animals, it can have significant implications for both animal and human health. Infected animals may experience illness, and in some cases, the disease can spread within animal populations, leading to outbreaks or epizootics. Additionally, infected animals can serve as a reservoir for the disease, potentially reintroducing it to humans or facilitating further transmission to other animals. Understanding the potential for reverse zoonosis is important for disease surveillance and control efforts. It highlights the need for monitoring and studying both human and animal populations to detect and prevent the spread of diseases across species.

WHO RESPONSE: –

WHO works with national governments, academia, non-governmental and philanthropic organizations, and regional and international partners to prevent and manage zoonotic threats and their public health, social and economic impacts. These efforts include fostering cross-sectoral collaboration at the human-animal-environment interface among the different relevant sectors at regional, national and international levels. WHO also works to develop capacity and promote practical, evidence-based and cost-effective tools and mechanisms for zoonoses prevention, surveillance and detection through reporting, epidemiological and laboratory investigation, risk assessment and control, and assisting countries in their implementation. As part of the One Health approach, the World Health Organization collaborates with the Food and Agriculture Organization of the United Nations (FAO) and the World Organisation for Animal Health (OIE) 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

Achieving One World, One Health: –

To achieve the vision of One World, One Health, international cooperation is vital. Collaboration between governments, international organizations, research institutions, and non-governmental organizations (NGOs) is essential for a coordinated response to zoonotic threats. This includes sharing data, expertise, and resources, and supporting capacity-building efforts in countries with limited resources. Investments in research and development are crucial for advancing our understanding of zoonoses and developing effective diagnostics, treatments, and vaccines. Furthermore, raising awareness among the public, policymakers, and healthcare professionals about the interconnectedness of human, animal, and environmental health is paramount to fostering behavioural changes and supporting policy reforms.

Prevention of public health problems through one health approach:-

The FAO/WHO/OIE document outlines key aspects

of animal welfare and public health, including Availability of infrastructure and expertise at national and regional levels and access points.

Timely identification and response to animals and humans and communication between the two.
An up-to-date emergency preparedness and response plan.
Ability to communicate the level of risk.
Compliance with international agreements and standards.
Continually evaluate and improve biosecurity.
Management and legislation comply with international standards.
Adequate capacity and capability in the laboratory supported by external quality assurance systems.
Establishment of monitoring and evaluation of veterinary and public health services.
Legal framework for providing incentives through cooperation with the private sector.

Conclusion:-

The world’s environment and human and animal populations are closely intertwined, and all three are currently at risk of extinction due to various factors. The only way to combat this alarming problem is through a coordinated global effort to implement the International health regulations, global health security agenda and One Health approaches, the latter being a comprehensive approach that targets the entire ecosystem. Coordination should be established between all stakeholders, including public health and veterinary authorities and agencies, environmental protection agencies, industry, research institutions, livestock traders and practitioners, and society at large. It is time for the world to come together and do all we can to protect the home ecosystem we all share. Zoonotic diseases pose a significant threat to global health security. The One World, One Health approach offers a comprehensive and collaborative framework to address these challenges. By recognizing the interconnectedness of human, animal, and environmental health, we can proactively prevent, detect, and respond to zoonotic diseases, creating a safer and healthier future for all. Through international cooperation, research advancements, and public awareness, we can work towards a world where zoonoses are effectively controlled, and the well-being of all species is safeguarded.

Reference:-

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