Back in 1999, unusually large numbers of dead crows in New York City signaled something was wrong. It turned out to be the arrival of West Nile virus in the United States, and today, the virus is endemic in the 48 contiguous states.
Since then, we’ve also seen Middle East respiratory syndrome (MERS) in 2012, the deadly Ebola virus in 2014 and the mosquito-borne Zika virus that began spreading widely last year.
So, are these rapidly emerging widespread outbreaks anomalies? Or is this the new normal confronting the United States and other countries? A recent study offers some hints at the answer.
The 2014 study, “Global Rise in Human Infectious Disease Outbreaks,” examined changes in the frequency of outbreaks of infectious disease between 1980 and 2013. The findings confirmed earlier reports that the number of outbreaks of emerging infectious diseases is growing and that zoonotic disease, which can be spread between animals and humans, continues to represent well over half of all infections in humans. In short, the study notes, the total number and diversity of diseases is continuing to increase.
A common thread in each of the recent cases has been the failure to anticipate the transnational spread of these diseases. Even once the outbreaks were detected, reactions were stilted, uncertain and under-resourced, all adding to public anxiety. Medical countermeasures and diagnostics were not been developed. In some cases, authorities initially gave unclear or questionable guidance to the public, including during the 2009 H1N1 influenza pandemic, when local authorities called for quarantines and school closures despite dealing with a relatively mild strain of influenza.
Prior to these emerging diseases spreading beyond their original isolated origins, there had been relatively limited understanding of them. But with each outbreak, the information known about the disease expands exponentially. Shortly after the suspected link between Zika virus and microcephaly in fetuses was announced, the director of the Centers for Disease Control and Prevention, Dr. Thomas Frieden, gave a briefing on Capitol Hill and described how the CDC file on Zika had grown from half an inch to over 5 inches thick in 30 days.
And Zika is not a new disease — its first reported occurrence dated to 1947 in Uganda. What was new was that it spread into multiple regions and became relevant to all nations in an increasingly connected world.
A recent commentary by Ronald A. Klain — a former White House Ebola response coordinator — should be required reading on the United States’ lack of preparedness for responding to the Zika virus. In it, Klain provided both a dire assessment of Congress’ uncertain funding support for the current response, and made longer-term recommendations for improving our rapid response to infectious disease outbreaks. Yet while these recommendations are spot on, including calls for a dedicated organization with specialized capability to respond to disease outbreaks, more must be done to ensure adequate preparedness against emerging infectious disease in the future.
The foundations for U.S. preparedness and response capabilities for dealing with infectious disease are biosurveillance and epidemiology. The first National Strategy for Biosurveillance, released in 2012, calls for detecting and understanding threats as early as possible, “including potential incidents of national significance that affect human, animal or plant health.” Diagnostic tests, historic outbreak data, open-source information, social media, environmental sensing, and national and international surveillance data are some of the tools that together provide a depiction of the current biological ecosystem and allow for sensing outbreaks.
Likewise, epidemiologists study distributions of, and establish causes for, disease for the purpose of better understanding and controlling diseases and other health concerns. The focus remains on solving immediate health and disease issues.
Yet both biosurveillance and epidemiology remain largely rooted in the past. A disease outbreak must occur, analysis conducted and the cause determined before action can be taken. They are retrospective analytical techniques. And while both are critically important, neither is sufficient to protect against future emerging infectious disease outbreaks.
So what should be done? This reactive approach to emerging infectious disease should be augmented with an anticipatory model that accounts for the dramatic changes occurring through globalization, greater interactions between human and zoonotic populations, and changes to the environment and climate patterns. For example, history indicates that certain climatic conditions lead to outbreaks of the hantavirus in the southwest U.S. desert. Expansion of trade and travel, meanwhile, can also serve as a pathway for the spread of disease as evidenced by the spread of MERS from the Arabian Peninsula to South Korea through infected travelers.
Armed with this knowledge, efforts to anticipate the global spread of disease over the next five, 10 and even 25 years should be undertaken. The goal should be to identify and correlate the various emerging infectious disease factors, estimate the likelihood of the migration of disease, focus research and development resources, identify and implement preventive steps and control measures, and prepare communities for rapid and measured responses.
Predictive analytical tools such as modeling and simulation, data mining, time series forecasting (a technique that predicts future values based on previously observed values), and pattern recognition will likely need to be employed. Such techniques would add necessary rigor to the forecasting goals specified in the National Strategy for Biosurveillance. To be fair, organizations such as the National Center for Medical Intelligence and Armed Forces Health Surveillance Center within the Department of Defense have been moving in this direction, but more needs to be done to expand knowledge of emerging diseases and better predict their spread.
Such efforts entail a long-term, multidisciplinary approach to better understanding disease from the cellular level to its impact within the broader biological ecosystem. Further, sustained interactions, including funding and leadership emphasis and at all levels of government — from state and local to national and international — will be essential. These efforts will, by necessity, include contributions from the private sector for continued advances in expanding the body of knowledge in emerging infectious disease and biotechnology.
Ultimately, if the U.S. and others are to manage emerging diseases like Zika, then their efforts will require strategies that focus on anticipating, not just reacting to, the serious challenges that these diseases pose.