From Habitat Loss to Human Health: Understanding the Rise of Zoonotic Diseases
Table of Contents
Abstract
Zoonotic diseases have become endemic worldwide, representing a major cause of global health issues. This paper explores the underlying causes and climatic factors driving zoonotic diseases, and analyzes effective strategies for their control. Through a comprehensive literature review, this research examines how these pathogens increasingly disrupt human activities. Despite extensive prior studies, zoonoses remain a primary threat to global health. Ultimately, this study emphasizes on actionable ways to promote a sustainable and healthy coexistence between human population and the environment. Keywords: Zoonotic disease, climatic factors, environment, endemic, population, health, pathogens
Introduction
Among the human pathogens, approximately 61% are zoonotic in nature (Rahman et al., 2020). It is estimated that more than 70% of these emerging pathogens originated from wildlife species (Rahman et al., 2020). These pathogens have different modes of transmission which can be via direct contact, ingestion, inhalation, through conjunctiva or biting. Furthermore, food borne pathogens have been proven to be one of the major causes of morbidity and mortality rates in adult and pediatric populations (Rahman et al., 2020). Zoonotic diseases originating from wildlife species pose a significant threat to global health, and economic growth. The COVID-19 pandemic, for example, caused devastating global mortality and severe economic downturns. By mid-2023, it resulted in the loss of 6.9 million lives (Zinsstag et al., 2023). Similarly, tuberculosis although it is not exclusively a zoonotic disease, remains one of the leading causes of death worldwide. A small proportion of these cases of zoonotic tuberculosis, are caused by infection with Mycobacterium bovis and transmitted from cattle to humans (WHO, 2024). More broadly, zoonotic diseases such as rabies, Ebola virus etc., have caused substantial morbidity, mortality, and socioeconomic disruption across the globe. These diseases have overwhelmed healthcare systems, disrupted trade and travel and imposed economic burdens to the affected countries. Therefore, understanding zoonotic diseases, their modes of transmission, climatic factors, and its implication to global health is of paramount necessity. This review examines these issues and highlights necessary steps in combatting them.
Zoonotic Diseases
Zoonotic diseases are infectious illnesses spread naturally between animals and humans. Over the past two decades, extensive research has been conducted to understand the mechanisms of zoonotic diseases. A case study by van de Garde et al. (2016) utilized a humanized mouse model characterized by chimeric human livers and a low immune profile to investigate the genetic behavior of the Hepatitis E virus (HEV). The study highlighted that HEV infections frequently remain asymptomatic and underdiagnosed. More broadly, emerging infections such as avian influenza, Ebola, and Hantavirus are increasingly re-emerging across many parts of the world. Because many of these zoonotic diseases originate in sylvatic cycles, their continuous emergence and re-emergence pose a significant global health threat. Epidemiological data indicates that viruses and prions account for 37% of these emerging and re-emerging pathogens while protozoa account for 25% (van de Garde et al., 2016).
Climatic and Environmental Factors Influencing Zoonotic Diseases
Climatic factors play a significant role in the emergence, distribution, and transmission of zoonotic diseases. Changes in climate, including global warming, increasing temperatures, altered rainfall patterns, flooding, and other extreme weather events, can influence the interaction between pathogens, animal reservoirs, and humans. These changes may affect the survival, reproduction, and geographical distribution of vectors and pathogens, thereby creating favorable conditions for the spread of zoonotic infections (Rupasinghe et al., 2021). However, climatic factors do not act alone, as several environmental and human activities also contribute to zoonotic disease emergence (Grigorieva et al., 2023). Factors associated with zoonotic outbreaks include international trade and travel, intensive animal husbandry practices, increasing animal food demand and related ecological disturbances, exploitation of wildlife, antimicrobial resistance, deforestation, and other activities that alter natural ecosystem (Grigorieva et al., 2023). Although these activities have great impact to human development and economic growth, their uncontrolled effects can cause adverse effects to the natural eco-system. Therefore, proper management of these factors is essential to promote the coexistence of humans, animals and the environment.
Prevention and Control Strategies
Due to the prevalence of these diseases, several strategies have been developed to strengthen the preparedness and response. The World Health Organization (WHO) developed the International Health Regulations (IHR) Monitoring and Evaluation framework which includes the IHR party self-assessment annual reporting tool and joint external evaluation (JEE) to assess countries’ capacities for preventing and responding to public health threats (Zinsstag et al., 2023). Furthermore, Calvin Schwabe in the 1960s coined out the term “One Medicine” to emphasize the shared health interests between humans and animals (Zinsstag et al., 2023), which later evolved into the broader One Health approach. Enhancing public health infrastructure, strengthening risk communication and response mechanisms, advancing research, and applying scientific findings in practice are essential components in controlling zoonotic diseases. In addition, effective surveillance systems and the use of mRNA vaccines remain crucial for early detection, monitoring, and rapid response to zoonotic outbreaks (Le et al., 2022).
Conclusion
Zoonotic diseases remain a major public health concern due to the interaction between humans, animals, and the environment. Understanding their causes and risk factors is essential for effective prevention and control. A One Health approach remains crucial in addressing these challenges.
References
Grigorieva, E., Babaeva, A., & Osipov, D. (2023). The environment as a source of
formation of hazards for humans. AIP Conference Proceedings, 2910(1), Article 02001 https://doi.org/10.1063/5.0175309
Le, T., Sun, C., Chang, J., Zhang, G., Yin, X. (2022). mRNA vaccine Development for
Emerging Animal and Zoonotic Diseases. Viruses, 14(2), Article 401. https://doi.org/10.3390/v14020401
Rahman, M. T., Sobur, M.A., Islam, M.S., Ievy, S., Hossain, M.J., El Zowalaty, M.E., Rahman,
A.T., & Ashour, H.M. (2020). Zoonotic Diseases: Etiology, Impact, and Control.
Microorganisms, 8(9), 1405. https://doi.org/10.3390/microorganisms8091405
Rupasinghe, R., Chomel, B.B., Martinez-Lopez, B. (2021). Climate change and zoonoses:
A review of the current status, knowledge gaps and future trends.
Van de Garde M.D.B., Pas, S.D., van der Net G., de Man R.A., Osterhaus, A.D.M.E.,
Haagmans, B.L., Boonstra, A., Vanwolleghem, T. (2016). Hepatitis E Virus (HEV) Genotype 3 Infection of Human Liver Chimeric as a Model for Chronic HEV Infection. J Virol 90. https://doi.org/10.1128/jvi.00114-16
World Health Organization. (2024). Global tuberculosis report 2024.
Zinsstag, J., Kaiser-Grolimund, A., Heitz-Tokpa, K., Sreedharan, R., Lubroth, J., Caya, F.,
Stone, M., Brown, H., Bonfoh, B., Dobell, E., Morgan, D., Homaira, N., Kock, R., Hattendorf, J., Crump, L., Mauti, S., Del Rio Vilas, V., Saikat, S., Zumla, A., Heymann, D., Dar, O., de la Rocque S. (2023). Advancing One human-animal- environment Health for global security: what does the evidence say? Lancet 401(10376):591-604. https://doi.org/10.1016/S0140-6736(22)01595-1
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