Emerging and reemerging infectious diseases (EID) have an important role in the modern world and leave long-lasting legacies. There is a long history of EIDs in humans, and they have varied greatly in type, transmission method, fatality rate, and cost. Most EIDs are zoonotic, meaning they originated in wildlife (typically in mammals), and have found their way into the human population. 70% of the 300 emerging infectious disease events between 1940 and 2004 were zoonotic in nature.[1] Furthermore, it is estimated that 25–44% of all zoonotic events have been due to viruses.[1] Viruses are particularly challenging due to their wide diversity and tendency to genetically mutate—making EID response strategies moving targets. The costs associated with EIDs are numerous and can be enumerated in many ways: in terms of lives lost (both among healthcare workers and the general population), the financial cost of response, social costs, and higher economic costs. The costs are both direct in the short-term and indirect over the long-term. The global cost of the 2003 outbreak of severe acute respiratory syndrome (SARS) is estimated to be between US$13 billion and US$50 billion.[2] More recently, the Centers for Disease Control (CDC) reports that the Ebola virus outbreak response in West Africa of 2014 cost roughly US$3.6 billion in total.[3] It is difficult to ascertain the true financial revenue lost as a result of an infectious disease outbreak, but history demonstrates that disease results in reductions in tourism, livestock value, exports, food production, and beyond.[4] EIDs also have devastating effects on health systems, resulting in reductions in preventive care due to reprioritization of resources toward outbreak response, declines in vaccination rates, loss of trained health care workforce members, and the additional burden of providing long-term care to survivors with chronic symptoms.[4]
Due to the inherent uncertainty in predicting the next infectious disease to emerge, the global community has shifted its focus and prediction efforts away from the general question of why is this disease emerging? to the question, why is this disease emerging at this time in this location? Four domains have been identified as central to estimating EID threats: 1) genetic and biological factors of pathogens and hosts; 2) physical and environmental factors; 3) ecological factors; and 4) social, political, and economic factors.[5] First, the nature of the infectious agent and the source from where it emerges are important. This domain is difficult to ascertain due to the need for disease identification and more detailed biologic understandings. There are programs actively working on testing large populations of wildlife for the presence of pathogens. Second, the physical environment, in particular weather and climate patterns, is seasonal and subject to change as a result of global climate change. This has led to recent expansion and movement in disease vector range. Third, the ecological factors in a setting, (i.e., land-use make-up, presence of large agricultural operations, and deforestation) are resulting in species movement and increased human-animal interactions. Finally, numerous social, political, and economic factors impact how humans interact with animals, the source of proteins, and sanitation availability. It is important to incorporate each of these factors when trying to predict the location of the next emerging disease. Some researchers believe that the reasons behind disease emergence should be disaggregated and described in more specific terms as “drivers” of disease.[6,7] Such drivers of disease include microbial adaptation and change, human susceptibility to infection, climate and weather, changing ecosystems, human demographics and behavior, economic development and land use, international travel and commerce, technology and industry, breakdown of public health measures, poverty and social inequality, war and famine, lack of political will, and intent to harm. Most of the disease outbreaks of international concern can be attributed to a single driver—lack of public health infrastructure. This has been amply evident from the Ebola outbreak in some of the Western African countries during this decade. EID prediction capabilities have improved drastically in recent years and are now monitoring additional “drivers” of disease emergence. However, there remains a challenge of establishing real-time data collection and processing at the ground level in most countries.
While there are numerous disease prediction programs and methods in use globally, there have been regions with significant histories of disease emergence that are under increased scrutiny to ensure continued political commitments and capacity building on many levels. It is important to exhaust all potential avenues to understand, predict, and respond to emerging infections. Furthermore, strategic development efforts can target specific drivers of disease emergence (i.e., public health infrastructure) through surveillance and system strengthening activities to ensure efficient and effective use of monies. There is an opportunity to learn from past outbreaks and work to develop an inclusive preparedness network with the ability to tweak and respond to any potential threat to arise. While emerging diseases are each unique, there are some control efforts, namely communication/collaboration and preparedness steps that are universal. The universality of some preparedness activities has already been acknowledged by international agencies that have worked to strengthen the International Health Regulations (2005) to respond to emerging disease threats.[8] Furthermore, some countries have made significant progress towards the achievement of the International Health Regulations and the establishment of strong disease surveillance and response plans. There is still an immense opportunity to assess capacities, develop policies, and plans to fill gaps and improve the operational quality of these systems around the world. Given their unpredictable nature, their direct impact on human health, as well as their wider environmental, economic, and societal impacts, EIDs require ongoing and sustained attention, funding, and response from the global community. The purpose of this paper is to understand the institutional capacities necessary to effectively respond to EIDs and highlight key strategies and potential points of intervention. We undertook a review of the literature to understand what an effective preparedness and response framework for EIDs would look like.