Prevention of future pandemics needs attention to planetary health: the example of bat ecology and COVID-19
K M Saif — Ur — Rahman
Health Systems and Population Studies Division, icddr,b, Bangladesh
Graduate school of Medicine, Nagoya University, Japan
Department of Public Health, Shiga University of Public Health, Shiga, Japan
Centre for Global Health, Institute of Health and Society, University of Oslo, Oslo, Norway
Emerging Scholar and Campus Ambassador, Planetary Health Alliance
Research Fellow, Centre for Global Health, Institute of Health and Society, University of Oslo, Kirkeveien 166, Frederik Holsts hus, 0450 Oslo, Norway
The transmission dynamics of the current global pandemic caused by SARS-CoV-2 are not fully understood yet. However, wild bats play an important role in the transmission of the recently emerged zoonoses. We aim to explore the role that the disruption of bat ecology has played in the COVID-19 outbreak. The question is what factors link bats to this public health emergency, and ask who is the real culprit — humans or bats. We argue that a better understanding of bat ecological factors in epidemic or pandemic causation will be crucial to understanding some of the planetary health aspects of such events, and preventing similar pandemics in the future.
The current Coronavirus disease (COVID-19) pandemic seems to have emerged from zoonotic transmission, since the causative virus isolated from early diagnosed cases in Wuhan shows 96% genomic similarity to bat coronavirus. Not only the recent SARS-CoV-2 outbreak, but several other coronaviruses (SARS-CoVs) causing severe acute respiratory syndrome (SARS) have been linked to their natural reservoir host bats since the SARS outbreak in 2002. A recent report has also identified a bat-derived coronavirus (RmYN02) very similar to SARS-CoV-2.
We observe that the switching of bat roosting behavior, from natural settings to artificial roosting in for instance buildings or concrete structures, may lead to increased human exposure to bats, resulting in increased incidents of zoonotic diseases.
Bat ecology and impacts of human anthropogenic activities
Environmental factors and conditions associated with roosting play an important role for bat ecology. Roosts are used for hibernation, mating, rearing progenies, food metabolism, social behavior and protection from threats. The ecology of roosting of bats is a synergistic series of events combining physiological, social, demographic and behavioral activities. The roosting habits of bats are influenced by availability of roosts, availability of foods, risks of predation, and the social and physical environment. Depending on their situation, bats need different types of roosts and they find roosts for meeting their needs. Popular bat roosts are hollow trees, caves, and even buildings with hanging tiles. Female bats find a maternity roost in summer whereas bats hibernate in winter using a hibernation roost. Although all sorts of places have been identified as bat roosts, they are typically either trees, underground sites or built structures.
With the emergence of human civilization along with changes in land use, natural sites for the bat roosting have become scarce. Consequently, artificial roosting sites are increasingly used by bats. Several studies focus on the sensitivity of bats to the changing environment. Climate change and land use are the most prominent causes of changed roosting behavior of bats. Roosts based on manmade structures provide an adaptable microclimate for the bats. The most common species of bats that prefer manmade structures are lesser and greater horseshoe bats, brown and grey long-eared bats and Natterer’s bats, which require flight access and space in the roost. However, such artificial roosts are also under threat due to renovations, use of more lighting and airtight buildings (amongst other things.)
Rethinking interactions in human and natural systems to ensure health and save lives
Disruptions in wildlife ecology, urbanization and simultaneous deforestation are considered predisposing factors for recurring outbreaks in the modern era. Increased and intensified human activity in forest areas, climate change and ecology have turned bats into reservoirs of emerging and reemerging pathogens including both RNA and DNA viruses.
Such pathogens are not only a health concern. The current COVID-19 pandemic is one of the greatest catastrophes of human civilization in the modern era, which has in addition to causing severe illness and deaths also disrupted many other indicators of prosperity, well-being and sustainable development. The enormous loss of lives and resources has made us understand better the importance of the planetary health concept, which focuses on the interaction between natural systems and human health, and has been described as “the health of human civilization and the state of the natural systems on which it depends”.
If we consider the global trend of pandemics and epidemics, the frequency has almost tripled at each decade from 1980s, and the major source of these outbreaks have been from wild animals. Surprisingly, the impact of climate change on public health was already a topic in the 1980s, when the United States Environmental Protection Agency first warned about global warming and the greenhouse effect in 1983.
However, the process of deforestation, agricultural land degradation and exploitation of wildlife by humans has in most places never been halted — it has rather intensified. In Norway, the transmission of infectious diseases from wild animals to domesticated animals and humans has remained low compared to many other countries. This is probably due to low population and animal density, favorable regulation related to wild life and nature conservation, as well as well-established disease surveillance systems, among other factors. It is also interesting to note that all bats are protected species in Europe. Nevertheless, despite these more favourable conditions in European countries, they have still been severely hit by the COVID-19 pandemic, illustrating the importance of focusing not only on the health of individual countries, but also on the universal achievement of planetary health.
Planetary Health efforts are needed to prevent future outbreaks
It is our understanding that disease transmission from wildlife to humans, including from bats or reptiles, is a rare phenomenon if their natural habitats are not interrupted by the abovementioned human anthropogenic activities. Bat ecology, including their roosting and food habits, can be affected to a large extent by human activities ranging from biomass production to simple traffic noise. Currently, major efforts are being put into producing new drugs and vaccines for COVID-19 control and prevention. However, efforts are also needed in the field of planetary health, to mitigate the similar pandemics in the future.
The current pandemic is a clear indication of our failure to realize and understand the importance of planetary health. While bats are considered as a crucial component of our ecosystem for their major role in pollination, seed dispersion and insect control, no drastic measures have been taken to improve their conditions, for instance related to roosting. Policies based on planetary health, such as nature based interventions with conservation of bats roosting behavior, reforestation and wildlife trade bans, are the most sustainable and effective measures to prevent similar pandemics and save human lives in the future.