Ragini Gupta, LLM student

We think of the HIV/AIDS epidemic as having begun around the 1980s, which is when the CDC first reported symptoms of a deadly pneumonia in clusters of previously healthy people in the U.S. The story, however, actually began in the 1920s when the virus jumped from a chimpanzee to a human in Central Africa in what is known as “zoonotic spillover.” “Zoonotic spillover,” or pathogens jumping from animals to humans, causes a large percentage of new outbreaks of infectious diseases.  Various factors can increase the risk of spillover; this post concentrates on habitat destruction and suggests environmental impact assessments incorporate an analysis on whether a proposed project may increase the risk of spillover.

What is zoonotic spillover?

“Zoonotic spillover” takes place when a disease that usually exists in non-human animals jumps to humans. 60% of infectious diseases that affect humans are zoonotic in origin. Some of the most serious epidemics in recent history originated from animals. Besides HIV, another example is the Ebola virus which is thought to have originated from fruit bats of the Pteropodidae family. Sometimes, a disease will leap through humans through an intermediate host such as in the case of avian influenza, which  spilled from waterfowl  to domestic poultry, which in turn  passed it on to humans.

Not every human-animal contact will lead to a spillover event, and not every spillover will result in an epidemic. Sometimes, a disease will spread from an animal to a human, but subsequent human-to-human transmission will not take place, such as in the case of rabies where human-to-human transmission through saliva is theoretically possible but has never been confirmed.  For a spillover event to be successful, a pathogen would have to jump through a series of natural hoops including reservoir density, pathogen survival and human exposure.

Why we should be concerned

The COVID-19 pandemic showed us the catastrophic consequences of infectious disease outbreaks. While not associated with as high a case fatality rate as some other viral diseases like SARS and Ebola, its high transmissibility resulted in havoc – with strain on hospitals and shortfall in oxygen, both of which resulted in excess deaths, and global shortage of medical supplies. This is in addition to the immense economic cost – according to one estimate, the pandemic will cost the U.S. alone between $ 10 trillion and $ 22 trillion.  Recent research has estimated that the probability of extreme epidemics can increase up to threefold in coming decades. Further, climate change is increasing the likelihood of zoonotic disease. As mammals are forced to shift their ranges when faced with increasing temperatures, new pairs of species will come into contact for the first time, resulting in an increased risk of viruses crossing between them – which could mean more diseases spreading to humans. Another way in which climate change might increase spillover risk is glacial runoff from the melting Arctic exposing viruses to new hosts. All of this would mean that the next potential pandemic is more imminent than we think. Spillover prevention thus must be a priority for policymakers.

What increases the likelihood of spillover?

Human-induced changes in land use are a  large driver of zoonotic infectious disease emergence. In fact, land use change has been called a “globally significant driver of pandemics,” and is said to have caused more than 30% of new diseasesreported since 1940. Other contributors to the risk of causing new diseases are wildlife trade and industrial animal farming . Human encroachment on natural habitats, for instance, through deforestation, poses a particularly serious threat– when a habitat is destroyed, species are concentrated together in the smaller remaining space, increasing the risk of spillover between them and of novel strains of viruses developing. Activities such as clearing forests then bring humans into contact with potentially infectious microbes.

Environmental legal frameworks need to incorporate spillover risk

Since the link between ecosystems and human health is becoming increasingly apparent, human health considerations must be accounted for in making environmental decisions. When decisions potentially altering habitats are taken, the risk of spillover needs to be taken into account to protect human health. An example of a habitat-altering decision would be granting permission for clearing a forest. To begin with, Environmental Impact Assessments should incorporate an analysis of whether a proposed action could potentially lead to a spillover. Environmental Impact Assessments (“EIA”) are globally widespread planning and management tools, intended to make sure that information to predict future impact on the environment is considered in the decision-making process. Many countries have adopted an EIA law or policy in some form, though these laws vary in terms of coverage.

For the purpose of this blog post, I will use the EIA framework in India as an example. EIA in India is governed by the EIA Notification, 2006 (“the Notification”) framed under the Environmental Protection Act, 1986.  As per the Notification, certain projects (listed in a Schedule to the Notification) require prior environmental clearance – this includes new projects and expansion of existing projects beyond specified limits. Examples of these projects are mining, infrastructure projects, and oil and gas transportation pipelines.

Appended to the Notification is a Form which specifies information a project proponent must furnish as part of its application – which includes whether existing land or vegetation will need to be cleared, whether there will be changes to hydrology of watercourses and whether native species will be lost or alien species introduced. While the Form includes a reference to “changes in occurrence of disease,” this is in the context of handling of hazardous substances and not alternation of habitats.

Submission of the Form is followed by a “scoping” process by which an expert appraisal committee (“EAC”) determines “terms of reference” reflecting environmental concerns which are to be addressed in an EIA report, to be submitted by the project proponent[1]. Then, during the “appraisal” stage, this committee scrutinizes the EIA report and other documents and recommends whether the regulatory authority should grant (with stipulated terms and conditions) or reject the clearance.[2]  The regulatory authority then considers the EAC’s recommendations and conveys a final decision to the project proponent. Inclusion of a question in the Form on whether a proposed project may increase spillover risk could be a starting point in making zoonotic disease concerns a part of environmental decision making . Based on the information supplied by the applicant in accordance with the Form, the EAC could determine suitable terms of reference in relation to spillover risk, which would then have to be addressed in the EIA report.  Incorporation of spillover analysis in the EIA framework in India could be significant, since the EIA is not merely a procedural requirement, and the regulatory authority is empowered to reject project proposals or stipulate conditions for acceptance.  For such a system to work however, EACs would need to include members with expertise in epidemiology and consultants (who typically prepare EIA reports) would both need to engage personnel who are knowledgeable in this regard and acquire the relevant technical know-how to analyze spillover risk. This is significant because at present most EIA experts have either a “technical and engineering”  or “natural environment” educational background.

Similar changes could be made in the EIA’s counterparts around the world. In the U.S., the National Environmental Policy Act (“NEPA”) requires federal agencies to identify and evaluate impacts of “major federal actions significantly affecting the quality of the human environment.”  Environmental Impact Statements (EIS) under NEPA should also include an analysis of whether a proposed federal action is likely to contribute to the risk of spillover. Though NEPA does not compel federal agencies to take any particular course of action, including such analysis in EIS can ensure that informed decisions with due regard to human health are taken by the agencies.

The practical difficulties of this suggestion are obvious – after all, spillovers have a certain random element to them and are hard to predict. It may be some time before it is technically feasible to implement a policy along these lines.  However, research suggests that while individual outbreaks are unpredictable, they do follow predictable patterns and it is possible to develop zoonotic risk assessment procedures which can consider virus species, conditions, or locations with a greater risk of such events. Researchers are already attempting to use machine learning to predict what potential spillovers may take place and where these may occur. One global hotspot map depicts spatial variation in zoonotic emerging infectious disease (“EID”) risk – tropical regions in the Americas, Asia and Central Africa have more extensive areas of predicted EID risk. As such research continues to develop, policymakers should devise means of incorporating such assessments into grant of environmental clearances.

Although I believe ecosystems have inherent value irrespective of their benefits to humans, we must recognize that ecosystem health and our own health might not be as detached as we have imagined.  Decisions we may perceive as relating to “the environment” may very well have direct consequences for the health of millions of people. It is time that law and policy start to reflect this fact.

REFERENCES

1. Nazneen Memon, How Did Aids Start? MedicineNet (2022) available at https://www.medicinenet.com/how_did_aids_start/article.htm
2. World Health Organization & Secretariat of the Convention on Biological Diversity, Biodiversity & Infectious Diseases – Questions and Answers
3. Ebola Virus Disease – Fact sheet by the World Health Organization (23 February 2021)
4. Aadrita Nandi & Linda J.S. Allen, Probability of a zoonotic spillover with seasonal variation, Infectious Disease Modelling (Volume 6, 2021)
5. Rabies – Fact sheet by the World Health Organization (17 May 2021)
6. Raina K. Plowright et al., Pathways to zoonotic spillover, Nature Reviews Microbiology (Volume 15, 2017)
7. A. Wilder-Smith, COVID-19 in comparison with other emerging viral diseases: risk of geographic spread via travel, Tropical Diseases, Travel Medicines and Vaccines (Volume 7, 2021)
8. Ben Hu et al., Characteristics of SARS-CoV-2 and COVID-19, Nature Reviews Microbiology (Volume 19, 2021)
9. Geoffrey French et al., Impact of Hospital Strain on Excess Deaths During the COVID-19 Pandemic — United States, July 2020–July 2021, Morbidity and Mortality Weekly Report – Centers for Disease Control and Prevention (19 November 2021)
10. Meenakshi Datta Ghosh et al., How India Can Prevent the Next Oxygen Shortage Crisis, Center for Global Development (24 June 2021)
11. Marco Marani et al., Intensity and frequency of extreme novel epidemic, Proceedings of the National Academy of Sciences (Volume 18 (35), 2021)
12. Chad P. Brown, How COVID‐19 Medical Supply Shortages Led to Extraordinary Trade and Industrial Policy, Asian Economic Policy Review (Volume 17(1), 2022)
13. Richard Bruns and Nikki Teran, Weighing the Cost of the Pandemic, Institute for Progress (21 April 2022)
14. Colin J. Carlson et al., Climate Change increases cross species viral transmission risk, Nature (28 April 2022)
15. Paul Logothetis, Climate change could make High Arctic fertile ground for emerging pandemics, University of Ottawa – Newsroom (19 October 2022)
16. Neil M. Vora et al., Want to prevent pandemics? Stop spillovers, Nature (12 May 2022)
17. Daszak et al., Workshop Report on Biodiversity and Pandemics of the Intergovernmental Platform on Biodiversity and Ecosystem Services (2020)
18. Pervaze A. Sheikh and Katarina O’Regan, Wildlife Trade, COVID-19 and Other Zoonotic Diseases, Congressional Research Service – In Focus (19 February 2021)
19. Stopping Deforestation Can Prevent Pandemics, Scientific American (1 June 2020)
20. Vanda Felbab -Brown, Preventing pandemics through biodiversity conservation and smart wildlife trade regulation, Brookings – Blueprints for American Renewal and Prosperity (25 January 2021)
21. United Nations Environment Programme, Assessing Environmental Impacts – A Global Review of Legislation (2018)
22. Urmila Jha-Thakur and Fatemeh Khosravi, Beyond 25 years of EIA in India: Retrospection and way forward, Environmental Impact Assessment Review (Volume 87, 2021)
23. Colin J. Carlson et al., The future of zoonotic risk prediction, Philosophical Transactions of the Royal Society B: Biological Sciences (Volume 376, 20 September 2021)
24. Katie Joy Sanchez, Machine Learning Used for Predicting Potential Viral Spillover from Animals, Verisk – Insights (17 May 2022)

[1] If the expert appraisal committee so recommends, the regulatory authority can reject an environmental clearance at this stage itself. Also, not all categories of projects require EIA reports and in these cases the decision to grant or reject clearance is made on the basis of the information in the Form the applicant as submitted.

[2] As per the Notification, the regulatory authority shall normally accept the recommendations of the expert committee, however it can request reconsideration by the committee if it disagrees with its recommendations. The regulatory authority however has the final decision.