Globalization, population growth, and urbanization have facilitated the transmission of infectious diseases. The complexity of global travel and global integration mean that any “patient zero” is now but a few degrees of separation from formerly isolated communities. According to medical experts, more than 30 new disease-causing organisms have appeared in just the past two decades. These have included such deadly pathogens as ebola, hepatitis C, and the human immunodeficiency virus (HIV). In addition, diseases such as cholera, malaria, and the plague, once believed eradicated, have returned with even greater virulence. In the first decade of the twenty-first century, the world was threatened by at least three major pandemics: SARS, H1N1 (“swine flu”), and H5N1 (“bird flu”). The hallmarks of globalization—connectivity and integration—create the potential for negative externalities in the field of health, just as they do in other sectors.

Goldin, Ian. The Butterfly Defect Princeton University Press. Kindle Edition.