One of the distinguishing features of the Obama administration’s approach to national security threats has been the priority given to infectious diseases. Clinton and George W. Bush established their own programs devoted in substantial measure to HIV/AIDS but the Obama administration, from 2009, dedicated far more of its security planning resources to outbreaks of infectious disease whether of natural, accidental, or deliberate origin and, more problematically for the current transition, tied at least some of those threats to climate change which, according to the White House’s assessment “create[s] conditions that promote pest outbreaks and the spread of invasive species as well as plant, animal, and human disease, including emerging infectious disease . . .”

There is good reason to prioritize infectious disease threats. Over the course of Obama’s presidency, influenza, Ebola, and Zika emerged as international public health emergencies. H5N1, H7N9 and other avian influenza viruses are increasingly infecting humans, MERS-CoV remains of uncertain virulence and prevalence (its spread in South Korea in 2014 was facilitated by “superspreading” events), and experts have so far identified only a tiny proportion of viral threats, and few of these viruses have had vaccines or other counter-measures developed. Over the coming century we will witness spillover from a pool of over one million “unknown” viruses into human populations.

Trump, by contrast, has made few references to the national security implication of infectious disease threats, with his most notable reference that tying infectious diseases to illegal immigration. So far, his picks for the national security leadership are intelligence and military strategists who suggest a focus on ideological and territorial threats cast in the kinds of terms that would have been as familiar to Nixon as Obama.

It is still early, of course, and Trump or his appointees may pick subordinates who demonstrate the same urgency about the threat posed by known and emerging infectious diseases as Obama’s national security team. That threat shows no signs of diminishing and, notwithstanding the possibility that some pathogens do in fact enter the U.S. through human agents traveling illegally, H1N1, Ebola, and Zika all arrived in the U.S. through legal entry.