This issue of Harvard Public Health, which is devoted to the theme of infectious-disease epidemics, could not be more timely. The public health profession put down its roots largely in efforts to control infectious diseases, from cholera and smallpox to tuberculosis and typhoid fever—in many cases even before science had the tools to isolate the pathogens behind those deadly scourges.
As the stories in this magazine illustrate, even in our era of extraordinary technological achievement, infectious disease demands our closest attention and utmost dedication. We are faced with spreading microbial resistance to antibiotics. This crisis is nothing more—and nothing less—than Darwinian evolution in action, perhaps the most formidable and complicated challenge in public health today. Malaria, an ancient disease, still accounts for more than 200 million cases yearly and claims some 435,000 lives. Ebola virus disease, with a case fatality rate ranging from 25 to 90 percent, is currently raging in the Democratic Republic of Congo, seemingly on the heels of the devastating 2013–2016 epidemic in West Africa. The incidence of dengue, a painfully debilitating infection in its most severe forms, has actually risen in recent decades—to an estimated 390 million infections per year.
The Harvard Chan School’s Bill Hanage, associate professor of epidemiology, often points out that the largest locus in the human genome is the major histocompatibility complex: a set of genes that codes for proteins that enable the immune system to recognize foreign substances—that is, infectious agents. This means that infectious disease has been the single biggest influence on human evolution. As molecular biologist and Nobel laureate Joshua Lederberg saw it, the contest between humanity and microorganisms could be a suspense thriller titled Our Wits Versus Their Genes.
At the International Conference on (Re-)Emerging Infectious Diseases, in Addis Ababa, Ethiopia—which was hosted by the Africa Centers for Disease Control and Prevention, and where I had the privilege of speaking in March—I was starkly reminded that humankind will forever be vulnerable to infections caused by viruses, bacteria, fungi, and protozoa. This permanent threat demands permanent readiness. How do we achieve that collective security? In part, with the understanding that every nation shares these risks—and the responsibilities to protect, promote, and preserve health. The threat of epidemics is as timeless as it is timely. We can never let down our guard. Across every department in the Harvard Chan School, we are working to ensure that when the next inevitable epidemic strikes, we have the knowledge and the tools to respond.
Michelle A. Williams, ScD ’91
Dean of the Faculty, Harvard T.H. Chan School of Public Health
Angelopoulos Professor in Public Health and International Development,
Harvard T.H. Chan School of Public Health and Harvard Kennedy School
Photo: Ben Gebo
