Preventive Medicine: Anaplasmosis to Zika: Good luck out there!

Dr. David Katz

Dr. David Katz

The CDC issued a report this past week highlighting dramatic increases in the rates of infectious diseases spread by ticks, fleas, and mosquitoes — otherwise known as “vector-borne diseases.” That list includes some long-familiar scourges, such as Lyme disease; some rather new to our lexicon in this part of the world, including Zika; some seemingly resurrected from Medieval parchment, like plague; and some long considered someone else’s problem, like dengue.

Covered by all of the major news outlets, the report is as important for what it barely says, as for what it asserts explicitly and emphatically. What’s emphatic is that rates of vector-borne disease have more than tripled in the U.S. in the past decade alone. That toll involves both more of the diseases we had reason to dread all along, such as Lyme, and threats formerly all but unknown here — such as the tropical disease, Chikungunya. What is explicit is that our public health and environmental systems are ill-prepared to contain this threat. Our resources are inadequate across the spectrum of treatment, surveillance, prevention, and control of the vector populations.

But what matters most is almost certainly what the report barely says, or omits entirely, about the reasons for this. Emerging infections are the result of changes in exposure, and those in turn result when people and pathogens find themselves together in new places, or when the environmental conditions of previously populated places change, making them hospitable to new agents of disease.

Both of these phenomena are occurring, in the U.S. and globally. The single greatest manifestation of environmental change is the climate. Media coverage of the CDC report all note in a seemingly understated way how understated the references to climate change are in the report. It is, as ever, the inconvenient truth. Among root causes of emerging and surging vector-borne diseases is a changing climate, for which we are obviously responsible. We cannot hope to manage the effect when systematically neglecting the cause.

The other factor — people and pathogens coming together in new places — is also a salient contributor, to some extent in the U.S., where our current environmental policies favor development over conservation — and even more so around the world. Globally, environmental encroachment is less a matter of presumption, privilege, and greed as it is here, and more a matter of basic human need. People move into new environments because there are too many people in familiar ones; because there isn’t enough land, or food, or water. The global population is a major driver of this, as is a failure to manage natural resources in ways that strike sustainable balances.

There are ways to address such things. There are shining examples of how to empower people with the means to produce their own food in sustainable ways; efforts to conjoin the health of people and planet; brilliant innovations that turn environmental conservation, clinical care, and economic opportunity into a single, harmonious continuum. But these are exceptions rather than rules, and never more so than now when the EPA seems to conspire actively against the environment, and when inconvenient scientific realities are simply declared inadmissible, and expunged from the policy dialogue.

Our failure to address root causes of vector-borne disease has an exact analogy in chronic diseases, such as heart disease, diabetes, cancer, and dementia. In this area, we received a provocative memo 25 years ago regarding underlying, “root” causes, and the critical need to address them. We have largely ignored that memo, and the result is that despite amazing advances in treatment, we have a massive increase in the burden of chronic disease, not the decrease that has long been achievable.

Public health and prevention seem only ever to get the love and resources they warrant in the fleeting aftermath of the latest calamity. We are presumptuous and arrogant enough never to mind our place in a nature greater than ourselves. We are greedy and shortsighted enough to feign acute concern with effects, while systematically neglecting causes of our own devising.

Nature’s minions — ticks, and fleas, and mosquitoes — don’t ever mind. They just adapt to exact an inevitable toll. Stated differently, at times the only reliable defense of the human body derives from an enlightened body politic. While waiting, good luck out there.