Global infectious diseases—The new norm for the United States?

Abstract

From 1900 to the end of the 20th century, and into the present, there has been a significant shift in the top ten causes of death in the United States (Tables 1 and 2). Where once infectious diseases were leading health care concerns, these have been largely replaced by cardiovascular disease and cancer. Unfortunately for a large proportion of the planet, infectious diseases remain the leading causes of death, disability, in some cases preventable blindness, and other serious sequelae. Because of our location, significant public health and medical infrastructure, and widespread immunizations against a wide array of pathogens, the US has been fortunately isolated from many infectious diseases, with the notable exception of tuberculosis (TB), HIV/AIDS, Lyme, West Nile, pneumonia, and influenza-related illness, as well as hospital-acquired infections. Of note, West Nile virus infections in the United States resulted in more than 140 deaths in 2006. Unfortunately most of the world still bears an enormous burden related to infections. Instead of recognizing that billions of people worldwide are exposed to important and emerging infectious diseases, our training has relegated this topic mostly to “tropical medicine” or public health or labeled the threat as a “zebra” item. While most of us remember from our early medical training the old adage “If you hear hoof beats, think horses, not zebras,” the US, and our attention, including medical training, can no longer afford to follow this adage or relegate these so-called “zebras” to the dismissed column, as many of them are important global health concerns. The world has come to our country as much as we have traveled to the world. And by extension—the world's diseases have come to our clinics, emergency departments, and health care facilities. Globalization, population shifts, and the changing ecology, including encroachment of previously unexplored regions, have altered the longstanding epidemiology of infectious diseases, causing spread where once continents and oceans contained the pathogen. New pathogens are occurring—some through unknown means and others through natural adaptation. It has long been recognized that influenza viruses exchange genetic material, either emerging as a new strain, as we continue to see with H5N1, H1N1, and now the latest H7N9. But this likely holds true for other viruses, as recently demonstrated with a novel coronavirus, most recently referred to as Middle East respiratory syndrome (MERS CoV). Social determinants of health—poverty, overcrowding, lack of infrastructure in many developing nations and in our own cities, which leads to poor sanitation, inadequate clean water, under-immunization and lack of health care access, environmental changes resulting in