Detection of SARS-CoV-2 in wastewater raises public awareness of the effects of climate change on human health: The experience from Thessaloniki, Greece.

Introduction

The world has been officially confronting the COVID-19 pandemic since March 2020 with countries worldwide experiencing a pattern of infectious spikes and regressions. Not surprising, the first to note a surge in COVID-19 cases were environmental scientists. This finding has been derived from wastewater analysis [1]. Scientists around the world have developed methods to detect viral RNA in sewage collected for biological cleaning. While the worldwide accuracy of predictions has been variable, wastewater analysis conducted by a multidisciplinary working group in Thessaloniki, Greece has been praised for its promising results [2].

The critical element of their success is a physicochemical model rationalizing SARS-CoV-2 concentration in wastewater [3]. Porous solids, such as soil and rubbish, may absorb viral fragments, decreasing the measured viral load and the subsequent ability to predict infectious surges. Environmental factors such as flow rate, suspended solids, quality and quantity of organic matter have been used to optimize the detection of viral components. Along with this, the working group in Thessaloniki, Greece, took into account the concept of “total environment” in an attempt to decrease discrepancies in measuring viral loads by previous research groups worldwide. "Total environment," is a novel term pertaining to the interaction of physical and anthropogenic environmental factors. In this context, climate change contributes to the disruption of the balance between the non-living (atmosphere) and the living (biosphere and anthroposphere) systems of the environment, which seems to be related to the emergence of SARS-CoV-2.

The intricate relationship between climate change and SARS-CoV-2

The intricate relationship of SARS-CoV-2 with the environment and climate change in particular, has contributed in bringing two distinct endeavors, human health and climate adaptation, under the same roof. Evidence suggests both direct and indirect links between climate change and the emergence and transmission of SARS-CoV-2 to humans. The repercussions of climate change, such as extreme weather patterns, include record-setting droughts and increases in number and intensity of hurricanes. Deforestation and destruction of wildlife habitats has increased contact between humans and other species, resulting in an increase in the number and frequency of zoonotic diseases. Subsequently, the selection pressure of life forms, including viruses, has escalated, while the buffer of disease transmission between animals has decreased [4]. Although the final pathway is not fully elucidated, it is clear that environmental disruption increases the risk to humans of zoonotic pathogens, such as SARS-CoV-2 [5].

There is an indirect socioeconomic association between climate change and SARS-CoV-2. Recent upward trends in extreme climate events have resulted in the mass migration of populations throughout the globe. In 2019, it was estimated that more than 33 million people across 145 countries and territories were forced to relocate [6]. Underserved, impoverished communities are frequently forced to live in overcrowded, urban centers. They often have no other choice but to live in small housing units which may have multiple families and multiple generations of inhabitants. This has hastened the spread of SARS-CoV-2. At the same time, affluent populations have made global travel for business or leisure the social norm. This has led to an increase in the rate and extent of communicable diseases worldwide, while simultaneously contributing heavily to our carbon footprint.  This is a vicious cycle, further exacerbating climate change [4].

The effect of climate change on wastewater

Climate change has affected wastewater both quantitatively and qualitatively. First of all, an increase in indoor plumbing along with an increase in population and extreme weather events lead to a higher volume of wastewater. At the same time, the rise in temperature due to global warming affects the ecosystems implicated in the collection and deposition of wastewater. Increased sewage has been observed in urban environments, where heavy metals are easily accumulated and atmospheric pollutants, such as methane and nitrous oxide exert a direct impact on the development of microbial communities within standing- and wastewater [7]. During 2020, elevated concentrations of heavy metals have been detected in rivers of the Netherlands, posing long-term toxicity risk for the population in the region [8]. Higher temperatures and atmospheric CO2 levels have contributed to these findings. Moreover, according to Sterk et al. climate change has been associated with an increased risk of infections by stable pathogens such as cryptosporidium and norovirus, in both the western world and the low and middle-income countries (LMICs) [9]. Such findings have certainly shifted the spotlight of the environmental health to prevention and diagnosis of waterborne infections.

Wastewater surveillance as a barometer of the pandemic and its implications on environmental awareness

In the past, wastewater surveillance has contributed to the prevention of infectious disease outbreaks by effective surveillance and timely monitoring of waterborne pathogens. In fact, wastewater is directly linked to the dawning of epidemiology, since the founder of this field, John Snow, gained traction when he identified sewage as the source of a cholera outbreak in London and managed to break the infectious chain by sealing the contaminated wells [10]. During the last decades, waterborne infections have been observed in LMICs, where wastewater treatment is precarious. For example, an upsurge in gastrointestinal infections in Kampala, Uganda in 2016 [11] and in Hanoi, Vietnam in 2017 [12] were attributed to the patients’ proximity to the wastewater systems. With the death toll due to waterborne infectious diseases being significantly higher, even in Europe [13], the United Nations has included water and sanitation in the Sustainable Development Goals framework [14].

The COVID-19 pandemic marked the first time when the detection of pathogens in sewage has led to sanitary precautions useful for the whole population. Research conducted on wastewater in Thessaloniki, Greece, raised local awareness about the reliability of environmental scientists to make predictions about the course of the pandemic [15]. While lockdowns and travel restriction policies have had a positive impact on the environment [16,17], wastewater analysis has been acting as a barometer. Elevated viral load in the wastewater, would precede a COVID-19 surge, alarming the public health authorities about increased SARS-CoV-2 transmission in the community several days before a spike in cases. While Greece's hardships from the pandemic have been aggravated by the limited capacity of ICU beds and COVID-19 wards, wastewater surveillance would allow the authorities to enforce precautions earlier. On numerous occasions, the national healthcare system reached its maximum capacity. It is noteworthy to mention that without the precautions taken following the increase of the SARS-CoV-2 wastewater viral load, this capacity could have been breached, leading to numerous hospitalizations and deaths.

Despite mounting misinformation, mainstream/social media have generally had consistent messaging with regard to wastewater surveillance. News was conveyed either by representatives of the scientists working on this analysis or by journalists. Despite the technical nature of the matter, maintaining a common approach towards the interpretation of these findings helped the majority of the public to get a grasp of wastewater surveillance and its environmental connotations [18].

Emerging evidence suggests that wastewater analysis amidst the pandemic, has increased public awareness about wastewater and sanitation [19]. Particularly in Greece, people regard wastewater as a barometer of viral load. This understanding can be extrapolated to the concentration of other pathogens putting public health in peril at a local or national level. Simultaneously, the pandemic has been an opportunity to re-educate the general population in the fundamentals of hygiene, infection control, and the relation of the pandemic to climate change.

The potential connection between these dots can be better communicated in the future. For instance, hand hygiene is a source of wastewater. Hand wastewater can reflect the viral load in the community, which is affected by infection control measures and environmental conditions. On the other hand, in case of future natural disasters associated with climate change, it is likely that wastewater management infrastructures will be damaged and wastewater will pollute potable water sources. This stated, wastewater is not only a source of information about infections, but may also be source of infection, per se. Climate change appears then as a common denominator, that may contribute either to the transmission of zoonotic diseases to humans or to microbial contamination by wastewater. Therefore, climate change awareness can pave a way to public health literacy and vice versa. Certainly, to spread awareness, it is necessary to use multiple platforms on both the mainstream and social media [20].

The importance of mainstream and popular media through the lenses of wastewater issues

The experience of the last months suggests that the public tends to become more receptive towards wastewater and COVID-19 news briefs combined with facts about the effect of floods on wastewater. The success of wastewater surveillance programs in monitoring the progression of the COVID pandemic, with public acknowledgement of such, provides a unique option to translate this awareness to climate adaptation [21].

The time is now to capitalize on the traction gained during the pandemic by highlighting the role wastewater analysis also plays in climate-related events such as floods. Specifically, news briefs and press releases should be aimed at public education by focusing on informative content written in plain language with facts on extreme weather events and its relationship to illness, along with strategies for adaptation and mitigation. Creating space for experts and science communicators in the media can help reveal the bigger picture; how wastewater surveillance to detect disease early and hand wastewater contamination of drinking water due to extreme weather events are connected.

Use of social media provides an ideal platform to promote such public service campaigns and reach a wide audience. In this frame, it is pivotal to use plain language to explain the technicalities and translate this understanding in clear recommendations for action oriented to climate mitigation and adaptation, the so-called antidotes to climate change. Certainly, taking into account the exposure of the younger generations to these concepts, stakeholders should make sure to include this knowledge in educational curricula from primary schools to universities. From such a standpoint, schools and other formal and informal educational entities can become more active in protecting the environment and producing a generation of environment – oriented learners and doers.

Conclusion

Overall, the COVID-19 pandemic has evolved into an opportunity to cultivate environmental awareness. Wastewater contamination and surveillance serves as a reminder of both the detrimental effect of climate change on human health and wellbeing and need for action to protect the environment.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.