Why this book?: Chapter 1 in Disease emergence and resurgence: The wildlife-human connection

Circular 1285-1




The appearance and diagnosis in humans of various infectious diseases is a dynamic situation involving “new” diseases that continue to arise and challenge humankind, along with fluctuating levels of established diseases. Some of the agents causing these diseases originate in humans and others in animals. As a group, the zoonoses (diseases transmissible between animals and humans) are of special concern because of the close associations people have with domesticated species and free-ranging wildlife. In many areas of the world, those associations with wildlife have become greater during recent years, especially as the increasing human population results in wildlife and people sharing more of the same space (Fig. 1.1). In addition, the popularity of outdoor recreation and ecotourism results in millions of humans entering “wild places” (Fig. 1.2). During 2001, 39 percent of the USA population 16 years old and older participated in activities related to fish and wildlife. These activities generated 1.1 percent of the Nation’s gross domestic product ($110 billion).2 Because of these factors, zoonoses are the dominant type of infectious disease in the current era of disease emergence and reemergence, a situation that is likely to continue for the foreseeable future (see Chapter 2). Not only can humans contract diseases from wildlife (Fig. 1.3), but humans can introduce diseases that jeopardize wildlife.3,4 Wildlife populations that become infected by pathogens typically considered to cause human disease may then become enzootic foci for those infections. Recent infection of African wildlife with the human strain of tuberculosis (Mycobacterium tuberculosis) has been attributed to the expansion of ecotourism and is but one example of disease introduced into wildlife populations associated with human encroachment into remote areas.4–7

Three basic factors can minimize the potential for diseases present in nature, such as AIDS, from becoming established as new diseases of humans, and can help to protect humans from long established zoonoses, such as rabies: 1) knowing the natural history of animal diseases transmitted to humans, 2) raising public awareness about the diseases they may encounter, and 3) implementing sound practices and public policy to address those diseases. Minimizing the introduction of typically human infections into wildlife populations is complicated because less is known about disease transmission from humans to free-ranging wildlife. A better understanding of the dynamics involved is essential for identifying mechanisms for limiting wildlife exposures to those infections.4 In addition to human illness and death, zoonoses are a threat to the sustainability of wildlife populations and impose heavy economic, social, and institutional costs.

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Why this book?: Chapter 1 in Disease emergence and resurgence: The wildlife-human connection
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U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
National Wildlife Health Center
16 p.
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USGS Numbered Series
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Disease emergence and resurgence: The wildlife-human connection (Circular 1285)
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