specific, the authors state. Now the agency—much like the Food and Drug Administration (FDA) as described by Acheson in the previous chapter—is engaged in developing a “risk based, proactive approach to preventing the importation of animals and vectors that pose a zoonotic disease risk,” according to Marano et al. This effort, which they describe in some detail, focuses on the systematic and targeted surveillance of high-risk animals, animal products, and vectors in their countries of origin.

Rapid expansion of trade and transportation during the Industrial Revolution resulted in the global proliferation of mosquito-borne diseases, such as dengue and chikungunya. Thanks to today’s globalized economy, these and other vector-borne diseases—once considered well-controlled in industrialized countries—are poised for resurgence, while others, such as West Nile viral fever and chikungunya, have significantly expanded their geographic range. In his contribution to this chapter, workshop speaker Paul Reiter, of Institut Pasteur, examines the role of human activities in the dispersal of several important insect vectors (such as the mosquito species that transmit malaria and yellow fever to humans) and of vector-borne diseases of both humans and animals, including chikungunya, West Nile viral fever, Rift Valley fever, and bluetongue. He also predicts future range expansions for certain vectors and vector-borne diseases; for example, he expects that Aedes gambiae, “perhaps [the] most effective malaria vector on earth,” will migrate northward out of its native home in sub-Saharan Africa, and also across the Atlantic to South America.

Reiter, who captured the first specimen of the mosquito species Aedes albopictus in the United States in 1983, and who subsequently discovered that this Asian native had been distributed globally in shipments of used tires, observes that, while “it is not difficult to survey a species once it has been detected, it is much more difficult to detect new introductions when they occur, particularly when cargoes are imported in locked containers.” Therefore, he concludes, “with a few exceptions—e.g., the enforcement of vaccination requirements—we must expect the continued establishment of new exotic species as an inevitable consequence of modern transportation technology.”

Might it be possible to prevent the emergence of infectious diseases by anticipating and blocking the movements of pathogens into new ecosystems? This question is posed by speaker Andy Dobson of Princeton University and Sarah Cleaveland of the University of Glasgow in this chapter’s final essay. Through a detailed examination of the circumstances that led up to the emergence of Nipah virus in Malaysia, the authors provide a number of insights into how other “novel” pathogens are likely to emerge, and they suggest a series of general questions that must be answered in order to predict and prevent future outbreaks of emerging infectious diseases.

To quantify the risk presented by a novel microbe to a potential host, Dobson and Cleaveland explain, information must be gathered and assessed at each of several stages in the development of an epidemic, from characterizing the back-

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