Environmental Protection Policy and the Emergence of New Diseases: A Global Empirical Analysis of the Pre- and Post-industrial Era

The environment exerts a significant role in determining human physical, biological, social and mental wellbeing (Abdallah et al., 2017; Davis and Sharp, 2020). Biodiversity conservation is a crucial component of environmental sustainability, which plays a pivotal role in maintaining ecological balance and ensuring healthy as well as functioning ecosystems. However, the emergence of industrialization in the 19^th century brought along a myriad of environmental challenges, such as deforestation and deterioration in air and water quality, resulting in an inevitable ecological damage due to forest destruction and consequently a rise in infectious diseases from zoonotic pathogens.
       
In the late 19^th and early 20^th centuries, governments across the world realized that policy development and promulgation of laws and regulations for protecting wildlife and nature-reserves were necessary. As a result, manifold summits and conferences were held to address the most challenging environmental problems requiring international attention. Davis and Sharp (2020) advocated the “One Health” concept as an inclusive approach to solving continuously complex global health challenges, considering the interconnectedness of human, animal and environmental health. Many invertebrate animals dwelling in our immediate vicinity are of epidemiological importance as they play important roles in transmitting pathogenic diseases to humans (Musoke et al., 2016).
       
About 25% of diseases devastating the world today occur due to prolonged exposure to environmental pollution (Musoke et al., 2016; Davis and Sharp, 2020). Besides, epidemiologists and environmental health scientists endeavored to understand historical trends of diseases and appraise therapeutic and preventive measures to develop appropriate policy and decision-making. However, little attention was given to assessing the relationship between environmental protection policy and the emergence of new diseases. Here, we identified and analyzed the key drivers contributing to the relationship and implored appropriate remedial and preventive actions to be taken.

This study was conducted at the Department of Environmental Science and Engineering, Hohai University, Nanjing, PR. China, from February 2020 to August 2021. The study’s methodology was based on the employment of secondary data sources. Table 1 summarizes the sources of information used in the analyses. In order to obtain reliable data, we introduced two criteria, namely, data verification and data validation. To verify each set of the received data, we arranged the data in a chronological list based on originality date and source conformity. We also separated the qualitative and quantitative data sets; a data cleaning analysis was conducted to remove the irregular and inconsistent data sets. Finally, we compared the two data sets (old and new) for verification.
 

       
For data validation, before analysis, data obtained from various sources were collated, transformed and configured to suit the employed analytical approach (Indika, 2011). In this study, about 89% of the data obtained were valid. Pearson correlation was used to determine the relationship among different variables. The probability level of certainty is accepted at a 95% confidence limit (CL) or α = 0.05. Calculations were performed using a Statistical Package for Social Sciences (SPSS) version 22 (IBM, Armonk, NY) and a Microsoft Excel 2013 program (Microsoft, Redmond, WA).

We analyzed the world’s eight major forest ecosystems with a total landmass of 9,353,946 km² in the post-industrialization period. The results revealed an estimated 11,537 (0.12%) km² of wildlife habitat loss, with the highest in South America’s Amazon Forest (84%), followed by the Congo Rainforest in Africa (10%) and the lowest in the Asian Kinabalu National Park and the Daintree Forest of Australia (0.01% each) (Table 2). Loss of wildlife habitat is significantly correlated with an increase in mortalities (r = 0.84; p<0.05) (Fig 1A) as a result of an imbalance in zoonotic pathogen/wild-animal eco-equilibrium, which subsequently led to the emergence of new (virulent) diseases in the human population. However, no associations were observed between time intervals of pandemics and changes in mortalities, as illustrated in Fig 1B.
 

 

       
From 430 BC to today, the world has experienced 28 different pandemics caused by 12 different classes of pathogenic bacterial and viral spp (Fig 2). Variola major virus, the cause of smallpox, remained in humans for the most extended period (62% longer of all pandemics duration) while RNA virus 1 was the shortest (0.05%) (Table 3). The highest mortality stems from the bubonic plague (caused by Yersinia pestis), which, although not very highly virulent (42.9%), spread across a vast geographical region. At the same time, the more lethal Ebola virus killed less than 12,000 people due to its limited transmissibility. Notably, no correlations were observed between pathogen persistence and the interval of pandemics (Fig 3A). Yet, there is a weak relationship (r = 0.27) between the duration of pandemics and fatalities (Fig 3B). More so, mortality rates depend on both the virulence of the pathogen and the ease of its transmission, i.e., a pathogen of relatively low virulence but with a rapid means of transmission can cause more mortality compared to a highly lethal pathogen with limited transmission capability. More often, underlying health history and social status exacerbate the situation.
 

 

 

       
The majority of diseases ravaged the globe ranging from the ancient Plague of Athens in 430 BC to the current COVID-19 pandemic, are limited to five continents, namely, Africa, Asia, Australia, Europe and North America, but not South America or Antarctica (Table 4). The highest relative cumulative death toll is in Asia (36.4%), closely followed by Europe (34.9%). Australia has the lowest mortality rate and the shortest duration of a pandemic. It is interesting to note that in the pre-industrialization era, pandemics were attributed to infections from three types of pathogens, namely, Salmonella typhi, Variola major virus and Yersinia pestis. The latter accounted for 68.4% of all deaths during this period (Table 5), with only smallpox (caused by Variola major virus) considered to have been completely eradicated (Kumar, 2016; US CDC, 2020).
 

 

       
While the Sustainable Development Goals (SDGs) No. 6 of the United Nations emphasized that industrial technologies, recent wave of economic globalization and infrastructural development have led to a growing health concern (Spier, 2011; Ibrahim et al., 2021). The findings in this study also showcased the need for global natural habitat conservation as the complexity in the nexus between wildlife habitat loss and pathogen spreads was majorly identified by the rise of industrialization in the late eighteenth and early nineteenth centuries (Spier, 2011). In those days, high morbidity and mortality were mostly due to poor sanitation, unsafe water supply and lack of understanding of the causes of infectious diseases.
       
Post-industrialization anthropogenic activities resulted in natural habitat encroachment, are negatively impacting the pre-existing natural ecological systems and compelling closer contact of wild animals with the intruding human population. For instance, in the 1950s, the natural forest coverage in Xishuangbanna, PR China, was >50% of the total area; however, by 1978, the coverage decreased to 34% and the natural forests have continuously been destroyed to make way for shifting cultivation and rubber tree plantation (Zhu, 1992). Consequently, the interaction between humans and wild animals in the forests increases, paving a way for the possible emergence of new diseases. When the effects of industrialization and urbanization on forests and human health were realized, various governments developed regulations for wildlife protection, urban hygiene, sanitation and appropriate housing facilities. For instance, in the USA, the Endangered Species Act (ESA) was passed by Congress in 1973 as a policy to conserve forests and wildlife (Ballotpedia, n.d.).
       
Notably, among the 324 ×10⁶ mortalities caused by global pandemics, 68% are due to wildlife-related zoonotic diseases. Our study reveals that, in South America’s Amazon Forest alone, 9,762 km² of forest are lost every year and this has been linked to the deaths of millions of people, mainly caused by zoonotic diseases. In Africa Congo Rainforest, more than 30% of deaths from zoonotic diseases are linked to the loss of 12,000 km² of wild animals’ habitats.
 
Our survey reveals that >10% of the total deaths caused by global pandemics from 430 BC to 2021 were from water-related diseases, accounting for
>33×10⁶ deaths. However, another critical source of epidemics is vector-borne pathogens. In Africa during 2013-Yellow-fever, an acute viral hemorrhagic disease transmitted by infected mosquitoes was responsible for 84,000-170,000 severe cases and 29,000 - 60,000 deaths (WHO, 2019). In particular, Aedes aegypti is a vector for not only the yellow fever virus but also that of dengue fever, chikungunya, Zika fever and Mayaro viruses.
              
Furthermore, water stress exists whenever annual water supply of a given region decreases to <170,000,0000 cm³/person, approximately between eight and nine glasses of water per day (Acciona, n.d.). The UN reported that one in six persons on this planet experiences this situation, which is a global situation that is becoming increasingly acute (Acciona, n.d.). The problem of water stress is especially evident in sub-Saharan African countries (Kyne, 2015; Wikipedia, 2020b). Many communities still rely on rainwater due to the inaccessibility of potable water (Abebe, 2020; Angela et al., 2019). Water shortages facilitate the proliferation of re-emerging diseases, such as Lassa fever in some parts of Africa, stemming from stored water contaminated with urine/feces of infected Mastomys rodents (WHO, 2018; Joshi, n.d.). Therefore, the positive impacts of environmental protection policies would never be overemphasized, as the rapid expansion of human activities in agriculture and industry led to the development and implementation of the policies by both government and private sectors. These policies are vital in thwarting threats of anthropogenic activities on ecosystems and, more importantly, ameliorating existing damages and preventing further abuse of the planet’s fragile ecosystems (Bhaurah, 2020).

This study demonstrated a strong connection between negligence in environmental protection policies and the emergence of new diseases globally. Among the causative pathogens, Yersinia pestis (cause of bubonic plague) was the most fatal pathogenic agent accounting for 40% of deaths from all the pandemics that scourged the world from 430 BC to the present day. The persistence of a pathogenic agent had a significant impact on mortalities. Although waterborne pathogens constitute a major cause of diseases, yet, water stress on the other hand could be a giant contributing factor. Therefore, it is imperative that “all hands should be on deck” to maintain a sustainable utilization of the existing natural resources and biodiversity conservation, bearing in mind that future generations may not share this mindset. Although our study focused on forest habitats, future studies should examine other portions of the ecosystem, such as the ocean, desert and mountains, so that a holistic picture of the relationships among all other components of an ecosystem and human health will be of paramount concerned.