Reflection essay about how the changes in our relationship with the environment have led to increase in incidence of certain disea


Reflection essay about how the changes in our relationship with the environment have led to increase in incidence of certain diseases and even result in pandemics.

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Athena 2 months 2021-07-28T00:21:57+00:00 1 Answers 0 views 0

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    Emerging infections, as defined by Stephen Morse of Columbia University in his contribution to this chapter, are infections that are rapidly increasing in incidence or geographic range, including such previously unrecognized diseases as HIV/AIDS, severe acute respiratory syndrome (SARS), Ebola hemorrhagic fever, and Nipah virus encephalitis. Among his many contributions to efforts to recognize and address the threat of emerging infections, Lederberg co-chaired the committees that produced two landmark Institute of Medicine (IOM) reports, Emerging Infections: Microbial Threats to Health in the United States (IOM, 1992) and Microbial Threats to Health (IOM, 2003), which provided a crucial framework for understanding the drivers of infectious disease emergence (Box WO-3 and Figure WO-13). As the papers in this chapter demonstrate, this framework continues to guide research to elucidate the origins of emerging infectious threats, to inform the analysis of recent patterns of disease emergence, and to identify risks for future disease emergence events so as to enable early detection and response in the event of an outbreak, and perhaps even predict its occurrence.

    In the chapter’s first paper, Morse describes two distinct stages in the emergence of infectious diseases: the introduction of a new infection to a host population, and the establishment within and dissemination from this population. He considers the vast and largely uncharacterized “zoonotic pool” of possible human pathogens and the increasing opportunities for infection presented by ecological upheaval and globalization. Using hantavirus pulmonary syndrome and H5N1 influenza as examples, Morse demonstrates how zoonotic pathogens gain access to human populations. While many zoonotic pathogens periodically infect humans, few become adept at transmitting or propagating themselves, Morse observes. Human activity, however, is making this transition increasingly easy by creating efficient pathways for pathogen transmission around the globe. “We know what is responsible for emerging infections, and should be able to prevent them,” he concludes, through global surveillance, diagnostics, research, and above all, the political will to make them happen.

    The authors of the chapter’s second paper, workshop presenter Mark Woolhouse and Eleanor Gaunt of the University of Edinburgh, draw several general conclusions about the ecological origins of novel human pathogens based on their analysis of human pathogen species discovered since 1980. Using a rigorous, formal methodology, Woolhouse and Gaunt produced and refined a catalog of the nearly 1,400 recognized human pathogen species. A subset of 87 species have been recognized since 1980—and are currently thought to be “novel” pathogens. The authors note four attributes of these novel pathogens that they expect will describe most future emergent microbes: a preponderance of RNA viruses; pathogens with nonhuman animal reservoirs; pathogens with a broad host range; and pathogens with some (perhaps initially limited) potential for human-human transmission.

    Like Morse, Woolhouse and Gaunt consider the challenges faced by novel pathogens to become established in a new host population and achieve efficient transmission, conceptualizing Morse’s observation that “many are called but few are chosen” in graphic form, as a pyramid. It depicts the approximately 1,400 pathogens capable of infecting humans, of which 500 are capable of human-to-human transmission, and among which fewer than 150 have the potential to cause epidemic or endemic disease; evolution—over a range of time scales—drives pathogens up the pyramid. The paper concludes with a discussion of the public health implications of the pyramid model, which suggests that ongoing global ecological change will continue to produce novel infectious diseases at or near the current rate of three per year.

    In contrast to other contributors to this chapter, who focus on what, why, and where infectious diseases emerge, Jonathan Eisen, of the University of California, Davis, considers how new functions and processes evolve to generate novel pathogens. Eisen investigates the origin of microbial novelty by integrating evolutionary analyses with studies of genome sequences, a field he terms “phylogenomics.” In his essay, he illustrates the results of such analyses in a series of “phylogenomic tales” that describe the use of phylogenomics to predict the function of uncharacterized genes in a variety of organisms, and in elucidating the genetic basis of a complex symbiotic relationship involving three species.

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