Graphical Abstract
#17,879
The COVID emergency was declared over in May of 2023 by the WHO and the nations of the world, but the virus continues to spread and evolve at an impressive rate (see CDC statement on JN.1); both in humans, and in non-human hosts.
Between a `milder' Omicron variant, and varying degrees of acquired immunity (from exposure or vaccines, or both), the worst certainly appears to be over.
But global surveillance and reporting systems have been largely dismantled, making it impossible to say with confidence how many people continue to be infected, hospitalized, or killed by the virus (see No News Is . . . Now Commonplace).
The $64 question is whether COVID was a one-and-done aberration - or, as we've seen over the centuries with novel flu viruses - just the first in a series of SARS-CoV inspired pandemic threats.
Like influenza A, the SARS-CoV-2 virus is highly mutable, and can infect a wide range of animal hosts. Both are qualities that increase its pandemic potential. Additionally, SARS-CoV-2 is far from the only zoonotic coronavirus on our radar (e.g. MERS-CoV, SARS-CoV, and PDCoV & SADS-CoV).
We've seen warnings from many quarters on the potential for SARS-COV-2 to reinvent itself in a non-human host, possibility spilling back into humans. A few examples include:
EID Journal: SARS-CoV-2 Infection in Beaver Farm, Mongolia, 2021
Viruses Review: SARS-CoV-2 Outbreaks on Mink Farms - Virus Infection, Spread, Spillover, and Containment
The Lancet Microbe: Ecology of SARS-CoV-2 in the Post-Pandemic Era
CCDC Weekly Perspectives: COVID-19 Expands Its Territories from Humans to Animals
Nature: CoV Recombination Potential & The Need For the Development of Pan-CoV Vaccines
Despite a growing number of reports of SARS-CoV-2 circulating and evolving in non human hosts (see here, here, here, and here), much of what is occurring in the wild happens outside of our view. We hear little or nothing from vast swaths of Asia, Russia, Africa, and the Middle East, but even in Europe and North America we see only the tip of the iceberg.
All of which bring us to a review article, published in Eco-Environment & Health. that examines the current literature on animal infections with SARS-CoV-2 and explores potential management strategies from a One Health perspective.
This is a lengthy, and scholarly report that reminds us that there are substantial gaps in both our surveillance, and in our understanding, of how SARS-CoV-2 fits into our shared global ecology.
While we play catch up, the virus continues to evolve, and expand its influence.
Follow the link to read it in its entirety.
Review
SARS-CoV-2 infection in animals: Patterns, transmission routes, and drivers
Ruying Fang a, Xin Yang a, Yiyang Guo a, Bingjie Peng a, Ruixuan Dong a, Sen Li a, Shunqing Xu b
https://doi.org/10.1016/j.eehl.2023.09.004Get rights and content
HighlightsAbstract
- Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected animals worldwide, most notably in South America, North America, and Europe.
- Biophysical determinants, such as landscape features, air quality, and host susceptibility, are factors that affect the transmission of viruses to animals.
- Anthropogenic drivers include human behavior, intensive livestock farming, animal markets, and land management practices.
- Asia and Africa have significant data gaps on SARS-CoV-2 infections in domestic and wildlife species, indicating a need for closer monitoring.
- A One Health approach is necessary to prevent transmission of the virus between humans and animals sharing the same physical spaces.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is more widespread in animals than previously thought, and it may be able to infect a wider range of domestic and wild species. To effectively control the spread of the virus and protect animal health, it is crucial to understand the cross-species transmission mechanisms and risk factors of SARS-CoV-2. This article collects published literature on SARS-CoV-2 in animals and examines the distribution, transmission routes, biophysical, and anthropogenic drivers of infected animals. The reported cases of infection in animals are mainly concentrated in South America, North America, and Europe, and species affected include lions, white-tailed deer, pangolins, minks, and cats.
Biophysical factors influencing infection of animals with SARS-CoV-2 include environmental determinants, high-risk landscapes, air quality, and susceptibility of different animal species, while anthropogenic factors comprise human behavior, intensive livestock farming, animal markets, and land management. Due to current research gaps and surveillance capacity shortcomings, future mitigation strategies need to be designed from a One Health perspective, with research focused on key regions with significant data gaps in Asia and Africa to understand the drivers, pathways, and spatiotemporal dynamics of interspecies transmission.1. Introduction
Since December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a global pandemic [1], leading to around 676 million confirmed human cases and over 6.9 million deaths worldwide as of March 10, 2023 [2]. The initial outbreak was reported at the Huanan Seafood Market in Wuhan, China [3], where wild animals traded in the market were suspected to be responsible for the initial infection and subsequent spread of SARS-CoV-2 [4].
The origin of SARS-CoV-2 remains unknown, but current evidence suggests that it may have evolved from animal hosts such as bats [5,6] and pangolins [7], both of which are natural reservoirs for SARS-CoV-2-like coronaviruses. A meta-transcriptomic study identified several SARS-CoV-2-associated and SARS-CoV-associated viruses in 411 bat samples collected from Yunnan Province, China [8]. The bat-CoV RaTG13 was found to share 96% genomic similarity with SARS-CoV-2, while the pangolin-CoV was detected with 91.02% and 90.55% genomic similarity to SARS-CoV-2 and bat-CoV RaTG13, respectively [9,10]. The receptor binding domain of the pangolin virus protein has five essential amino acids identical to those of SARS-CoV-2, which could make pangolins susceptible to intermediate hosts in the evolution of the virus [11]. Molecular epidemiological studies suggest that the emergence of SARS-CoV-2 was likely the result of multiple zoonotic spillover events [12]. However, little is known about the spatiotemporal pattern and underlying factors of animal outbreaks of SARS-CoV-2 before the pandemic.
There is increasing evidence of transmission of SARS-CoV-2 between humans and animals. Cases of infection have been reported in various domestic and wild species such as lions [13], white-tailed deer [14], pangolins [15], minks [16], and cats [17]. A mink-adapted SARS-CoV-2 variant virus was found in a high-density mink farm in Denmark, leading to zoonotic spillover [18]. Infected hamsters in a pet store in Hong Kong transmitted the pathogen to the store staff [19], highlighting the potential for animal–human transmission. As the virus continues to circulate in animals, it is difficult to predict how potential mutations might emerge and what evolutionary changes they might lead to.
The announcement of the end of the SARS-CoV-2 pandemic may have been premature, as the Omicron variant is highly transmissible yet causes milder symptoms [20]. While this may suggest a potentially stable and predictable pattern of transmission, some experts disagree, pointing to Omicron's greater mutability and lower lethality than previous strains [21]. They suggest that the virus may persist as a public health threat for decades to come, necessitating continued vaccination efforts for future generations due to its potential to infect animals and mutate further. Moreover, even if the virus were eliminated in human populations, SARS-CoV-2 could continue to pose a risk to human health and domestic and wild animals through hidden reservoirs in wildlife [22]. Therefore, continued research is crucial for understanding the transmission and evolution of the virus, developing effective public health measures, and safeguarding against potential animal-to-human spillovers.
Taking a One Health approach to combat SARS-CoV-2 requires a comprehensive framework that incorporates an understanding of the socio-ecological processes driving the epidemic pattern and synergistic strategies to promote population, animal, and environmental health. Thanks to improved scientific communication and data sharing, researchers can now monitor the real-time progression of SARS-CoV-2 in human populations [5]. However, a more thorough comprehension of the establishment of SARS-CoV-2 in animals and the factors contributing to pathogen transmission between humans and animals is still needed. This study reviews the current literature on animal infections with SARS-CoV-2 to gather the latest evidence on both biophysical and anthropogenic drivers of disease emergence, identify gaps in current knowledge, and explore potential management strategies from a One Health perspective. The results of this review can provide policy makers with decision support for developing guiding policies that manage the risk of SARS-CoV-2 outbreaks in animals.
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Fig. 2. Global distribution of SARS-CoV-2 infection in animals according to the World Organization for Animal Health. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
4. Conclusion
This study provides a comprehensive review of the current literature on the patterns, transmission routes, and drivers of SARS-CoV-2 outbreaks in animals. Based on the results of available monitoring reports, animal infections of SARS-CoV-2 have been reported mainly in South America, North America, and Europe, with bats being proposed as the natural reservoir of the virus. However, the precise intermediate host and transmission pathways remain uncertain. In addition to domestic animals, free-ranging, captive, or farmed wild animals, such as big cats, minks, ferrets, North American white-tailed deer, and great apes, have been observed to be infected with SARS-CoV-2. Notably, farmed minks and pet hamsters have been confirmed to be capable of transmitting the SARS-CoV-2 virus to humans.
Despite a limited number of reported cases of animal-to-human transmission, substantial gaps persist in our understanding of the transmission pathways between animal species and humans. Symptoms resulting from SARS-CoV-2 infection exhibit variation across diverse animal species. Furthermore, the ongoing mutations of the virus pose a formidable challenge to the preservation of endangered animals, underscoring the significance of vigilant monitoring and dedicated conservation efforts.
This paper's novelty lies in its comprehensive analysis of the biophysical and anthropogenic factors influencing SARS-CoV-2 infections in animals. It offers a broader perspective on zoonotic disease transmission and its implications for global animal health conservation, paving the way for further research in this critical area. It highlights the impact of climate, population density, and landscape changes on different transmission routes of the virus. Sites involving human–animal interaction, such as markets and farming of susceptible animals, are considered focal areas for pathogen transmission. The increase in recreational activities and wildlife–human contact worldwide may also contribute to the rapid spread of the virus.
To fully implement the One Health concept, there is a need for a further understanding of SARS-CoV-2 transmission pathways in shared spaces between humans and animals and the development of management strategies to prevent intra- and inter-species transmission. The study's identification of key animal species and biophysical and anthropogenic factors could assist in developing and implementing prevention strategies to interrupt cross-population transmission routes and prevent the evolution of pathogen reservoirs in the biosphere.
