The emergence of COVID-19 is a powerful reminder of how unchecked wildlife trade can lead to the spillover spread of viruses between wildlife and humans. Understanding that wholesale bans on trade can affect community livelihoods and food security, the pandemic underscores the need for widespread pathogen screening and monitoring to better understand, predict and contain outbreaks in wildlife and humans.
To date, global biosurveillance has consisted of centralized efforts led by governmental and specialized health agencies. A group of authors--including eight researchers from San Diego Zoo Global--writing in the journal Science this week offer an efficient approach that may be more resilient to fluctuations in government support and could be utilized even in remote areas.
Given the importance for the health of a global population, the team of scientists recommend a "decentralized" disease surveillance system, enabled by modern pathogen-detection methods, which builds in-country capacity for addressing challenges. Utilizing portable molecular screening that is both cost-effective and relatively easy to use, this network would take a more fundamentally proactive approach to wildlife screening, they write.
The COVID-19 crisis has shown that the international wildlife trade is a global system in need of greater oversight. However, ill-conceived measures such as 'blanket bans' could affect millions of people and drive these activities deeper underground, further impeding our efforts to understand and reduce demand for wildlife."
Elizabeth Oneita Davis, Ph.D., Conservation Social Scientist in Community Engagement at San Diego Zoo Global
The network should expand monitoring beyond human disease outbreaks to encompass a broader understanding of pathogens and evaluate their spillover risk (of spreading from wildlife to humans or vice versa), they write. To this end, surveillance focal points should include wildlife markets and farms, as well as free-ranging populations of "high-risk" wildlife.
"Since the H1N1 outbreak of 2009, which spurred governmental responses such as PREDICT to begin active virus hunting in zoonotic hotspots, genomic technologies have transformed radically," said Mrinalini Erkenswick Watsa, Ph.D., lead author and conservation geneticist on San Diego Zoo Global's Population Sustainability team. "Sequencing the genome of a virus is now feasible on miniature sequencers, directly at the point of sample collection. Today, we can more directly and powerfully survey wildlife health, identify areas of high spillover potential and contribute to minimizing those behaviors, to keep human and wildlife populations safe," she said.
Key to this approach is the creation of a pathogen database to provide early warnings of spillover potential, and assist in containment and development of therapeutic treatments.
"A decentralized approach to biosurveillance would more readily address wildlife and ecosystem health, and therefore conservation as a whole," said Steven V. Kubiski, DVM, Ph.D., a veterinary pathologist on San Diego Zoo Global's Disease Investigations team, who co-authored the perspective piece. "The ability to test multiple populations is just the beginning--a centralized location for deposition, analysis and reporting would add even more value, and could serve as an open-access resource."
The authors note that beyond endangering human health, emerging infectious diseases can imperil wildlife populations that have not evolved resistance to unfamiliar pathogens.
Additionally, the authors call for an internationally recognized standard for wildlife trade, the risks of which they call the "largest unmet challenge" for infectious disease surveillance. Despite the known risks, little monitoring takes place in wildlife markets like the one believed to be the original vector of the SARS-CoV-2 virus.
"Decentralized pathogen screening in wildlife lends itself not only to early detection of pathogen spillover into humans, but helps conservation veterinarians and disease experts understand the natural host-pathogen relationship, allowing us to better conserve wildlife populations and save species," said Caroline Moore, DVM, Ph.D., Steel Endowed Pathology Fellow and veterinary toxicologist on San Diego Zoo Global's Disease Investigations team, who was among the co-authors.
"The proposed disease surveillance model will help us inventory naturally occurring pathogens in different taxa across the globe, enabling us to track future changes in viruses and ecosystem health that are relevant to both humans and wildlife populations," added Carmel Witte, Ph.D., wildlife epidemiologist on San Diego Zoo Global's Disease Investigations team.
The authors point out the value of biobanking efforts, including those of San Diego Zoo Global's Frozen Zoo®, in assisting the worldwide surveillance effort.
This decentralized system is consistent with the collaborative, holistic disease mitigation strategy of the One Health approach, used by the Centers for Disease Control and Prevention. This approach seeks to decrease the threat of disease through the conservation of nature and ecosystem function, accounting for domestic animals and all other human-related factors.
Watsa, M., et al. (2020) Rigorous wildlife disease surveillance. Science. doi.org/10.1126/science.abc0017.