Risk Assessment Tools from the One Health Perspective: A Narrative Review

Introduction

Modern day human activities have accelerated the changes in the environment of our planet, affecting not only human and animal species but also the ecosystem as a whole. Recently there have been instances of inter-species transmission of diseases resulting in the spread of infection in new species. An infectious disease is a disease caused by a pathogen or toxin transmitted from an infected person, animal or inanimate object.¹ In 2013, 45 million years were lost due to disability, and over 9 million deaths occurred due to infectious diseases.² In 2019, 13·7 million people worldwide died from infectious diseases.³ Out of the total infectious agents identified globally to date, 61% are zoonotic and have the potential to be transmitted between humans and animals.⁴ According to the World Bank, the global expenses of zoonosis between 2000 and 2010 amounted to around $20 billion in direct costs and $200 billion in indirect costs.⁵ Experts predict that the risk of Zoonotic disease risks would increase with changes in the environment. The altered climate has led to change in the genomics of the pathogens as well as breeding pattern of the vectors which has impacted the risk of zoonotic diseases.

Global pandemics such as the recent Covid-19 pandemic have caused global crises. It not only had a high burden on the health system but also brought our lives to a standstill, highlighting that the control and prevention of transmission depend on a comprehensive understanding of the elements that determine it.⁶ The administration got into the task of estimating the risk of the covid-19. This included estimating the risk of transmission concerning socio-economic and demographic factors impacting the spread of covid-19, vulnerable populations and coming up with measures to avoid the spread of the infection and keep the populations safe.⁷

Evidence indicates that there is a rise in the threat posed by zoonotic diseases, and the risk of a new pandemic is also very high. Among other approaches, early identification of risk, populations at risk, and risk of transmission are essential steps towards a better response, preparedness, and prevention of outbreaks.

Risk is the probability of having a negative effect on people, systems or assets. Risk is typically depicted as a function of the combined effects of hazards, the assets or people exposed to the hazard and the vulnerability of those exposed elements.^8,9

The risk assessment identifies actual or potential risks for the population as a whole or a particular section of the population, thereby coming up with measures to reduce those risks. Risk assessment mostly resides within the realm of science, technology, academics, and policymakers.¹⁰ Risk assessment helps identify and estimate risk, thus paving a path for its prevention and helping in policy-related decisions.

The outbreaks of SARS that emerged in the 21st century gave us the idea that novel pathogens could emerge from wildlife. The emergence of H5N1, avian flu and covid-19 proved the need for an effective alert and response system.^11,12 Risk assessment is carried out not only at the human but also at the animal interface. Among the various risk assessment tools available, they identify the risk for the environment as a whole or for the transmission in the community at the community or individual level. Healthcare professionals, researchers, and individuals utilize health risk assessment tools to analyze a person’s overall health and determine their risk of contracting specific diseases or ailments. With the use of these instruments, one can discover potential health hazards and determine preventive actions. Some tools are used to decide the method suitable for risk assessment in a particular circumstance.¹³ The tools are separate for animals or humans and in case of humans they estimate risk of very varied dimensions; thus, there is no tool to estimate the risk of zoonosis or transmission of diseases between wildlife and humans. This review aims to look at the tools available for identifying and estimating risks and threats from one health perspective and finally propose a list of indicators which could assess the risk of transmission of disease at the humans, animals and the environment intersection.

Methods

The review aimed to have an insight on the existing tools that can be used for identification or assessment risk at the human-animal-environment interface. An analysis of the literature regarding risk assessment tools published till November 2022 has been provided in the review. Articles with primary data sources are considered in this literature survey. The tools which assess the risk of transmission of infectious diseases were taken for assessment.

Operational Definitions

Risk is generally defined as the probability of an outcome having a negative effect on people, systems or assets.

Health risk can be defined as the likelihood that a given exposure or series of exposures may have damaged or will damage the health of individuals.¹⁴

Human health risk assessment is a process of assessing the risk to an individual or a population as a whole. The risk assessment usually starts with problem formulation and includes steps like hazard identification, hazard characterization, exposure assessment and risk characterization.

Search Strategy and Selection Criteria

The review includes tools which estimate or assess the risk of diseases. The databases like PubMed, google scholar, Embase and Scopus were searched for studies. Keywords such as “Risk assessment tools”, “Zoonotic Diseases”, “Infectious diseases”, “One-Health”, “Transmission of infectious diseases”, “Environment”, “Animals”, “Human health”, and “community transmission” were used to conduct the search and documents with risk assessment tools used in the context of infectious diseases or those applicable to the risk of transmission of infectious diseases. All articles were extrapolated, and criteria of risk assessment in the tools were enlisted.

Data Extraction and Quality Assessment

A total of 1311 articles were initially selected for review, and after review a total of 26 tools were included in the review. The excluded searches include multiple studies using the same tools or studies, including tools that cannot be used for infectious disease risk assessment. The studies that justified the exclusion and inclusion criteria were only included. The data that was extracted included the author details, year of publication, number of study participants, and factors used by the tools for risk assessment.

The PRISMA chart presented in Figure 1 gives an overview of the tools/papers included in the study. The results of this review have been synthesised using the extracted data.

Figure 1 Prisma Diagram.

Inclusion and Exclusion Criteria

The studies or documents with the risk assessment tools and elaborating the factors considered in risk assessment mainly dealing with exposure assessment of the risk or which assessed the risk were included. The tools assessing the risk of transmission of infections among humans or animals or the tools estimating the risk of health hazards at the workplace or environmental hazards are included, which can be further used in the context of infectious diseases.

The tools that assessed the risk of NCDs, injuries, falls or other health issues or assessed the severity or impact of a hazard were excluded. Studies that did not elicit the details about the tools or their usage have been excluded. The studies that used the same tools as other studies, those that do not assess the risk of transmission of infectious diseases, or those that cannot be used in the context of infectious diseases have been excluded from the study.

Results

The 26 tools which deal with the risk of Transmission of infections at workplaces, risk assessment at the environmental levels, animal health risks assessment, and human health risks assessment at the community and individual levels are included in the study. The basic characteristics of the tools have been enlisted in Table 1.

Table 1 Summary of Risk Assessment Tools with Its Practical Implications, Synthesised Based on the Review

Assessment Tools to Assess Health Risks Due to Environmental Factors

The tools are used to evaluate the contamination of the environment due to chemicals or toxins or the risk of Transmission of infection due to environmental factors like air contamination, as in the Wells-Riley model, and water contamination like CHWRA or QMRA.

The safety risk assessment toolkit by World Health Organisation (WHO) is helpful in identifying and recognizing the necessary information for evaluating the chemical dangers, levels of exposure, and associated health risks. It collects information on chemical assessment and its impact on human health. The details about the hazard-causing potential of the chemical, impact of the chemical on the population, determination of risk with respect to the amount of exposure, and assessment of Non-Cancer and Cancer risk.³³

Human Health Risk Assessment (HHRISK) is a tool mainly helpful in assessing the contamination of the environment due to chemicals. The technique incorporates a matrix that considers both space and time to assess the combined risk from numerous exposure paths and the cumulative risk from many sources.¹⁴

The Wells–Riley model is useful for examining ventilation strategies and their connection to airborne pathogens in clinical settings. This is a rapid assessment of the likelihood of contracting airborne diseases.^18,39 The process entails utilizing a distance index and a ventilation index to precisely measure the effects of social distance and ventilation on the likelihood of infection.³⁹

The Community Health and Well-being Risk Assessment (CHWRA) is an online tool used to record the existing health effects experienced in a specific local area. It also collects information on the duration of residency in the region. The CHWRA provides comprehensive and organized evaluations of health risks and potential benefits. This includes identifying the type, scope, and probability of risks. Waterborne illnesses, heat exhaustion, cancer, and related conditions.³⁷

Disease Attribute Intelligence System Tool (DAISY) is a tool to assess the spread of infectious disease in an area as well as monitor the risks of other new threats from a country’s perspective. The tool assessment depends on four major factors: threats or hazards inherent to the biological agent, vulnerabilities in surveillance and containment, Monitoring of biological agents or infectious diseases, and media or social support. This Tool is useful in case of emerging diseases.²³

Quantitative microbial risk assessment (QMRA) is a method to ascertain faecal contamination and hydrologic events in water bodies. QMRA may determine the level of safety of water, quantify the degree of variability in safety, and provide a measure of certainty in the safety estimate. This gives an idea about the safety of water from a particular site.³⁴

Ecological risk assessment (ECoRA) is a tool useful to predict the potential influences of contaminants of animal, plant or human sources that could affect an area or a locality. The primary focus of this study is on the measurement and quantification of pollutants in soil/sediments, plants, and creatures. It aims to directly assess the exposure of ecological receptors (animals, plants, and microbes) to contaminants present at the site. Additionally, the study collects information about the release, movement, and destiny of these contaminants.²⁴

Hazard Identification and Risk Assessment (HIRA) is a tool to quantify risks associated with hazards. This Tool mainly deals with hazard identification and assessment of the risk. This includes hazard identification in construction, operations and natural calamities.⁴⁰

Risk Assessment Tools to Assess Health Risks Due to Animal Factors

The risk assessment tools are present to identify the animal diseases like bovine respiratory disease and foot and mouth disease. There are specific tools to estimate the risk among a particular section of the animal population, like that of the risk of SARS CoV 2 virus among the animals used for fur farming.

Bovine respiratory disease risk identification tool used to identify the risk of bovine respiratory disease among pre-weaned calves. The tool assessment is based on herd risk profile, maternity pen management like pen density, bedding type, hygiene practices, and quality control; colostrum management includes storage and container type, milk feeding factors or nutrition factors including feeding order, milk source, pasteurization, and quality control, vaccination includes types and frequency of vaccines administered and calf housing factors includes housing material, calf to calf contact, presence of extra shade and manure flush system.²¹

FMD risk identification tool is useful in estimating the spatial variation of risk of infectious animal disease at a national scale. It can be used for diseases like foot and mouth disease. Tool assessment is based on local data, data on cattle type, permeability of virus, potential contact between wildlife and livestock, and level of herd immunity generated by prophylactic vaccination.^38,41

GLEWS+ The combined OIE/FAO network of experts in animal health conducts risk assessment to ascertain the transmission of the SARs CoV 2 virus among animals involved in fur production. The text explores the transmission risk of viruses from fur animals to wildlife, the risk of spill over to people, and the risk of virus transmission among fur animals. Therefore, it examines the probability and repercussions at the regional or national scale.³⁰

The quantitative microbial risk assessment tool calculates the health hazards resulting from the exposure to water polluted with feces and the diseases it carries. The evaluation relies on determining the concentration of certain pathogens at the locations where humans are exposed to the environment. This is commonly done by estimating the presence of pathogens in their sources and using models to predict how the pathogens will move and be distributed to the locations where humans are exposed. This information is then combined with the volume of ingestion to estimate the amount of pathogens that individuals are likely to be exposed to. The computed dosage is utilized alongside a corresponding dose-response model for each exposure pathway/pathogen combination to obtain estimations of health hazards.³⁴

Risk Assessment Tools Due to Human Physiological Factors

The tools found from the search estimate the human health risk at the community or individual levels.

Risk Assessment Tools Used at the Community Level

Rapid risk assessment tool for communicable disease risk in humanitarian emergencies is helpful to assess disease outbreaks in any humanitarian emergencies like natural calamities or war. The tool includes risk factors like water, sanitation and hygiene practices, health and socio political factors whose scoring is done to predict risk of communicable diseases.⁴²

Mass Gathering Risk Assessment Tool (MAGRAT) is a tool helpful in assessment of risk during the planning of a mass gathering event. It collects information on organisers’ experience, public transport, public agencies, and risk of weather, gatherings, or Transmission of infectious diseases like Covid-19.³²

The Influenza Risk Assessment instrument (IRAT) is an external evaluation instrument used to estimate the potential pandemic risk posed by influenza A virus among humans. The Tool gathers data on the “characteristics of the virus”, “characteristics of the population”, and “ecology and epidemiology of the virus”. It provides a perspective on the transmission of the virus from one human to another.³¹

The Public Health System Risk Assessment (PHRAT) evaluates the magnitude of particular risks by considering their effects on human health, healthcare services, community functioning, and the operations of public health agencies. The Healthcare System Risk Assessment analysis evaluates the severity of risks in two domains: human health and healthcare services, as well as the infrastructure of inpatient healthcare facilities.²⁷

The Egyptian HCV risk screening tool (EGCRISC) is a tool useful to screen HCV infection among the Egypt population. It estimates risk based on various risk factors like blood product transfusion, rural residence, fatigue h/o jaundice, h/o of PAT, incarceration, unsafe route of sex, contact with jaundice patient, use of barber or beautician tools, substance abuse, living abroad, hospitalization, needle prick, h/o invasive procedures, during intercourse, blood sample, labour and delivery at home.²⁵

WHO mass gathering COVID-19 risk assessment tool - generic events is used to assess the risk of a disease due to or during a mass gathering. It is based on the number of people, spacing, ventilation, event duration, travel footprint, travel routes.²⁸

Risk Assessment Tools Used at the Individual Level

“European Up‐Front Risk Assessment Tool” (EUFRAT) quantifies the potential for transmission of a newly identified infectious illness through the process of blood transfusion. The Tool calculates the number of individuals that contract an infection by blood transfusion, either during a regional outbreak of an infectious illness or due to donors visiting an area affected by an outbreak. The risk can be estimated using characteristics of the disease whose risk is being calculated and information about the disease and its outbreak, including the incidence rate, duration of the outbreak, infectivity duration and its latent period. It also uses information regarding donor screening and donation testing, blood component production and donor exposure, and susceptibility of the recipient of the blood.¹⁶

TIPRA tool for Influenza pandemic Risk Assessment is a tool to assess the risk of sustained human-to-human transmission of the virus. The characteristics like properties of the virus, including the receptor binding properties, genomic characteristics of the virus, susceptibility to anti-viral treatments, attributes in human population like human infection, disease severity and population immunity, virus ecology and epidemiology in non-human hosts including geographic distribution of animals, and infections in animals are considered in the Tool to assess the risk of viruses.²⁹

The risk assessment tool to detect maternal HIV infections includes scoring the number of sexual partners, behavioural factors like age of sexual debut, number of lifetime sexual partners, trading sex, condomless sex, vaginal washing and drying, and clinical factors like self-reported history of sexually transmitted infections [STIs], laboratory-confirmed C. trachomatis, N. gonorrhoea, T. vaginalis, syphilis, BV, and candidiasis has a good prediction ability to identify the women vulnerable to HIV.¹⁵

COVID-19 Risk Assessment Tool (RIKA) is a online tool to access individual risk based on the health, behaviours, exposure and social policy parameters. The health parameter includes age, co-morbidities gender, smoking habit. Behaviour parameter includes mask use, hand washing, sanitizing before touching face, practicing social distancing, and anxiety due to the pandemic. The type of residence, occupation, travel history and exposure to mass gatherings comprises exposure parameter. Effectiveness of lockdown, community compliance of social distancing comprises of social policy parameter.¹⁰

All Wales Covid-19 Risk Assessment tool is a tool to explore the outcomes through self perceived risk. It is a self administered tool to estimate an individuals risk of severe covid-19 infection by scoring personal risk factors. The factors like age, ethnicity, existing health conditions, Obesity and family history of susceptibility to covid-19 are considered in this Tool. It can identified to assess the risk of infectious diseases among the vulnerable population.²⁶

Risk Assessment Tools to Identify Risks Due to Occupation

Hazard Identification, Risk Assessment, and Control measures (HIRAC) is a tool for Occupational Health Assessment. This includes defining hazards characterized by the probability of the risks, frequency, severity of the risk, evaluation of adverse consequences, potential losses and possible injuries. This Tool includes steps like risk identification, analysis, evaluation and treatment. The factors based on which the assessment is done are the likelihood that the injury (or illness) may actually occur and the severity of the injury (or illness) resulting from the hazard.³⁵

Hazard and Operability Studies (HAZOP) is also a tool to perform risk identification and assessment in the workplace. It includes classifying potential hazards based on the attitude of the workers, safety measures taken, posture, and physical work environment. This Tool also reflects on the consequences of hazards at the workplace due to environmental contamination through analysis of operability on the deviations, possible causes, consequences, safeguards, and action required.²⁰

Hospital occupational safety, and health risk assessment (HOSHRA) is a tool to assess the risk of biological hazards for health care workers in a hospital. This Tool encompasses various categories of hazards, namely physical hazards (such as electrical, fire/explosion, fall/slip, and radiation), chemical hazards (including exposure to acids and bases, alcohol, ether, ester, formaldehyde, and detergents), biological hazards (such as needle stick and sharp objects, hospital waste, and bloodborne pathogens), ergonomic hazards (related to musculoskeletal disorders and environmental parameters), and psychological hazards (such as violence in the workplace, shift work, and job stress).³⁶

Risk Assessment Tool from the One Health perspective

Joint risk assessment operational tool (JRA OT) is an Operational Tool of the Tripartite Zoonoses Guide to addressing zoonotic diseases by considering a multisectoral approach from One Health perspective. It helps countries in the identification and prioritization of zoonotic diseases. The main assessment is based on various steps and it is mainly conducted when a health event emerges or occurs at the human-animal–environment interface.²²

Discussion

The risk assessment tools are essential part of prevention of pandemics. These tools are helpful in accessing the Risk of Transmission of infections either from human to human, between human and animals, between animals and animals and so on. The route of Transmission, the intensity of the risk, and characterization of risk is essential for prevention of Transmission thus thereby preventing an upcoming pandemic. The tools must be collectively used by various fraternities like human health, animal health and environmentalists thereby ensuring the health of the animals, humans and environment and evading the Risk of Transmission of infectious diseases. The dissection of tools from One Health perspective is mentioned in Table 2.

Table 2 Dissecting the Risk Assessment Tools from the One Health Perspective

Table 3 Summary of Variables Which Could Be Part of the One Health Risk Assessment tool

Factors to Evaluate the Human Health Risks

The demographic information like age, education, marital status, relationship status and duration need to be documented as Age, race and gender are the human attributes which significantly impact an individual’s risk of zoonotic diseases. As per ECDC a higher mortality rate is seen among males compared to females due to covid-19. In a study by Jones et al, the risk of infectious diseases is higher among older people than young people. Similarly, it was also seen that gender and race also had a correlation with chance of contacting infection. It was seen that married men had lower frailty than unmarried men, whereas married women had higher frailty than unmarried or widowed women.⁴³ Educational status plays an important role in awareness and knowledge, which finally helps in the prevention of zoonotic diseases. Education also has a key impact on the habits and behaviour of an individual.⁴⁴ The risk of zoonotic diseases increases based on the likelihood of exposure at workplaces. Some zoonotic diseases pose a significant risk for individuals of certain occupations.⁴⁵ In a study in Ethiopia, it was seen that the adherence to preventive measures was associated with age, level of education, occupation and knowledge.⁴⁶ Thus as considered in risk assessment scales like the human immunodeficiency virus (HIV) risk assessment tool for pregnant women, the Covid-19 risk assessment tool (RIKA) and the All Wales COVID-19 Workforce tool the demographic factors need to be included in the OH Risk assessment tool.

Factors like the likelihood of exposure to disease vectors through systematic surveillance of the pathogen give an accurate idea about human vector contact and the risk of exposure to the pathogen. Similarly, vector density also indicates the risk of human vector contact or animal vector contact, thereby providing with risk of vector-borne diseases⁴⁷ Reluctance to follow disease prevention measures, insufficient nutrient intake, and lack of hygiene are behavioural factors which have a significant impact on the overall health and wellbeing of an individual. Reluctance to follow protective and preventive measures puts an individual at risk of contracting an infection. Similarly, insufficient nutrient intake has effects such as poor growth, impaired intellect, and increased mortality and susceptibility to infection.⁴⁸ Lack of hygiene or water, sanitation and hygiene (WASH) increases the risk of diarrheal diseases and compounds the risk of infectious diseases.⁴² The history of jaundice, cancer, organ transplantation and other chronic conditions reflects the individual’s health status. It was seen that Chronic co-morbidities, including Obesity, hypertension, diabetes, cardiovascular disease, cerebrovascular disease, respiratory disease, kidney disease, and malignancy, are clinical risk factors for a severe or fatal outcome associated with COVID-19.⁴⁹ Thus, the details on the likelihood of exposure to disease vectors and information on adherence to preventive measures, insufficient nutrient intake and hygiene practices as documented by the risk assessment tools like A human immunodeficiency virus (HIV) risk assessment tool for pregnant women, rapid risk assessment tool for communicable diseases in humanitarian emergencies, Covid-19 risk assessment tool (RIKA), Risk Assessment Tool (DAISY) For Emerging Human Infectious Diseases and The community health and wellbeing risk assessment (CHWRA) needs to be included in the OH risk assessment tool. But the observatory tool or Tool to access risk at an individual level needs to be tailored appropriately to capture the information regarding the likelihood of exposure at workplaces or residential areas.

The increase in the number and frequency of international travels, migratory flows, health system failures, social inequalities, and geopolitical conflicts are factors that contribute to the emergence and spread of new pathogens in human populations.⁵⁰ Health system failure like lack of health facilities, lack of health workers, insufficient vaccine coverage, and Lack of medicines reflects the preparedness of the health system to manage an outbreak. Several initiatives have been rolled out during the covid-19 pandemic towards effective response to the pandemic and alleviating future threats.⁵¹

Factors to Evaluate the Animal Health Risks

The factors like Herd risk profile, maternity pen management, colostrum management, milk feeding, cattle vaccinations, and cattle housing are used to estimate the risk of bovine TB. Still, these will also be applicable for zoonotic diseases whose host or reservoirs are cattle or other poultry animals. The health status of animals is an essential component in risk assessment as most zoonotic diseases have emerged at the human-animal interface.⁵² The Risk of Transmission of pathogens from wild animals to cattle also needs to be documented as undertaken by GLEWS+ Risk assessment tool. These factors will evaluate the animal health risks. Thus, cattle management and WASH practices mainly associated with handling cattle or pets need to be observed along with the vaccination status of the cattle and the likelihood of Transmission of infection from wild animals to understand the chance of a zoonotic disease.

Factors to Evaluate the Environmental Health Risks

The causes contributing to the problem include insufficient access to potable water, inadequate sanitation facilities, and a suboptimal distance between homes and the disposal of animal and human waste. Waste water inundation The absence of waste management is seen as a factor in assessing the likelihood of communicable diseases in times of humanitarian crises. These parameters can be applied to a wide range of situations and are valuable for predicting the risk of transmission of zoonotic illnesses in the OH risk assessment tool.

Environmental risk factors include weather and climate factors, such as cold and dust storms, vector habitats, increased contact with animals, and endemic diseases. The environmental factors affect the distributions of zoonotic agents and their Transmission to humans.⁵³

The genesis and spread of novel infections in human populations are influenced by factors such as high population density, deforestation, geographic location, climate changes, and the increasing interaction between humans, livestock, and wild animals⁵⁰ In tropical regions, the alteration in climatic circumstances has resulted in the extensive proliferation of carriers and vectors of zoonotic viruses, hence augmenting the transmission of viruses from their carriers to animal hosts. Climate-induced alterations, such as variations in temperature and precipitation, can lead to genetic instability in the evolutionary makeup of viruses. This phenomenon has been observed in the case of the West Nile virus (WNV) in North America, where increased temperatures triggered an adaptive mutation that allowed the virus to replicate more efficiently at higher temperatures.^54,55 So, as per the risk assessment tools rapid risk assessment tool for communicable diseases in humanitarian emergencies and Tool for influenza pandemic risk (TIPRA) the factors to estimate the quality of care, environmental factors like deforestation, climate changes, and population density are necessary to estimate the risk of zoonotic diseases.

Mass vaccination of cattle reduces Transmission of diseases like Brucellosis^56. The presence of wet markets which sell live animals for food are also a source of the emergence of diseases⁵⁷ Thus, the presence of wet markets, the vaccination status of cattle also need to be captured to assess the risk due to animals or factors associated with animals.

Conclusion

As discussed in the review, many risk assessment tools are available, but they all estimate one aspect of risk in humans, animals, or their shared environment. The tools also sometimes estimated diseases specific risks. Thus, a One Health Risk assessment tool must be developed and validated considering various factors to assess human, animal, and environmental risks. This Tool will also help predict the outbreak of zoonotic diseases. The estimation of likelihood of an outbreak will be helpful in mitigation of risk and decreasing the chances of an outbreak. These estimations can be conducted among the high-risk population at a time interval. Such assessment results will alert us of a future outbreak, which will help us with timely interventions. This will also give us an idea about the recurrent OH risks and help to formulate policy to combat them at a greater level.

Future Perspectives

A thorough One Health risk assessment will help us to prepare policies for the betterment of everyone. A tool has to be developed which could be unanimously used by various departments for risk assessment in place of different tools during different contexts. An ideal One Health risk assessment tool must comprise the factors from animal health, human health and environmental well-being. The OH risk assessment will assess the risk of infection as well as the likelihood of an outbreak of disease.

The physical, biological, psychological and environmental factors are important in estimating risk. The physical factors like exposures of ecological receptors (animals, plants and microorganisms) to site contaminants, information about contaminant release, its migration and fate are crucial to detect risk. Similarly, biological factors like age, gender, presence of co-morbidities also predispose to estimation of risk. Psychological factors or behavioural factors like WASH practices, and consumption of alcohol are few factors which increases the risk of diseases. Environmental factors like access to clean water, distance from site of hazard, distance from reservoir also helpful in knowing the risk of zoonotic diseases. Thus, these factors need to be included in the proposed tool for One Health risk assessment.

The existing Joint Risk Assessment operational tool assesses risk on the indicators like Number or extent of the situation, target population, geographic location, Outcome, Hazard, source of exposure, and time frame but it does not look at the factors like likelihood of exposure, likelihood of contamination of environmental factors, and biological and behavioural factors of human which has a crucial role to play in the transmission of zoonotic diseases. Thus, we propose a tool with factors to analyse risk at the human, animal and environmental interface that can help us in early detection and mitigation of risk. The factors that could be included in the One Health risk assessment tool and the tools from which they are obtained are tabulated in Table 3. The factors that can be included in the tool are segregated based on the human, animal, or environmental factors in Figure 2.

Figure 2 Proposed future perspectives of the One Health Risk Assessment tool.

Further, this study proposes to implement and validate the suggested one health risk assessment tool in the global and local context for its replicability.