Emerging infections are defined as new, reemerging, or drug-resistant infections whose incidence in humans has increased within the past two decades or whose incidence has threatened to increase in the near future. An upsurge in infectious diseases can be attributed to societal changes, such as population growth and migration; changes in health care, such as the widespread use of antibiotics; the globalization of the food supply and changes in the ways we grow and produce our food; human behavior, such as widespread and frequent foreign travel; environmental changes that have resulted in flood, drought, and famine; decay of the public health infrastructure, which has led to the curtailment or elimination of programs for disease prevention and surveillance; and microbial adaptation and change, which have resulted in changes in virulence and the development of resistance to antibiotics. Unfortunately for the human population, conditions created by the rapidly changing human world are excellent for microbes.

Though the four articles in the journal seem to be on widely diverse topics, a second look will reveal that there are many commonalities in the diseases. The topics discussed in NEJM are: