Bonita F. Stanton, MD, *Consulting Editor*Despite much progress in their control, infectious diseases remain a global concern. The number of under-five deaths worldwide has declined from 12.7 million in 1990 to 5.9 million in 2015 (<http://www.who.int/mediacentre/factsheets/fs178/en/>). Globally, approximately half of under-five deaths are due to infectious diseases.[@bib1] Although numbers are substantially lower in industrialized nations including the United States, infectious causes remain among the top 10 causes of childhood mortality and cause significant morbidity (<http://www.kidsdata.org/topic/659/childdeathrate-age-cause>). Moreover, infectious diseases are continually emerging as new pathogens, as more virulent pathogens, and/or in new settings. In the past few years, the World Health Organization has noted the appearance of a Crimean Congo hemorrhagic fever, Ebola virus disease, Marburg virus, Lassa fever, Middle East respiratory syndrome, severe acute respiratory syndrome, coronavirus diseases, Nipah and Rift Valley fever (<http://www.who.int/medicines/ebola-treatment/WHO-list-of-top-emerging-diseases/en/>). Over the past year, Zika virus has emerged as a major threat in the Americas, including the United States (<https://www.cdc.gov/zika/index.html>).

Thus, there are many reasons it is important for every pediatrician to be familiar with extant and emerging pathogens from across the globe. First, we are a single globe, and health and wellness is our concern worldwide. Second, whether or not the pathogen is currently in the United States, it could easily arrive here---and thrive.

This issue of *Pediatric Clinics of North America* effectively summarizes a vast literature updating the health care provider on familiar infectious diseases and describing those that are newly recognized, emerging, and/or migrating. The issue is both fascinating and very helpful, written by true leaders in the world of childhood infectious diseases.
