Cooling off health security hot spots: getting on top of it down under

Establishing a theoretical foundation for measuring global health security: a scoping review

Background

Since the 2014–2016 West Africa Ebola epidemic, the concept of measuring health security capacity has become increasingly important within the broader context of health systems-strengthening, enhancing responses to public health emergencies, and reducing global catastrophic biological risks. Efforts to regularly and sustainably track the evolution of health security capabilities and capacities over time – while also accounting for political, social, and environmental risks – could help countries progress toward eliminating sources of health insecurity. We sought to aggregate evidence-based principles that capture a country’s baseline public health and healthcare capabilities, its health security system performance before and during infectious disease crises, and its broader social, political, security, and ecological risk environments.

Methods

We conducted a scoping review of English-language scholarly and gray literature to identify evidence- and practice-based indicators and proxies for measuring health security at the country level over time. We then used a qualitative coding framework to identify recurrent themes in the literature and synthesize foundational principles for measuring global health security. Documents reviewed included English-language literature published after 2001 until the end of the research period—September 2017—to ensure relevance to the current global health security landscape; literature examining acute infectious disease threats with potential for transnational spread; and literature addressing global health security efforts at the country level.

Results

We synthesized four foundational principles for measuring global health security: measurement requires assessment of existing capacities, as well as efforts to build core public health, healthcare, and biosecurity capabilities; assessments of national programs and efforts to mitigate a critical subset of priority threats could inform efforts to generate useful metrics for global health security; there are measurable enabling factors facilitating health security-strengthening efforts; and finally, measurement requires consideration of social, political, and ecological risk environments.

Conclusion

The themes identified in this review could inform efforts to systematically assess the impacts and effectiveness of activities undertaken to strengthen global health security.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7216-0) contains supplementary material, which is available to authorized users.

The emergence of arthropod-borne viral diseases: A global prospective on dengue, chikungunya and zika fevers

Arthropod-borne viruses (arboviruses) present a substantial threat to human and animal health worldwide. Arboviruses can cause a variety of clinical presentations that range from mild to life threatening symptoms. Many arboviruses are present in nature through two distinct cycles, the urban and sylvatic cycle that are maintained in complex biological cycles. In this review we briefly discuss the factors driving the emergence of arboviruses, such as the anthropogenic aspects of unrestrained human population growth, economic expansion and globalization. Also the important aspects of viruses and vectors in the occurrence of arboviruses epidemics. The focus of this review will be on dengue, zika and chikungunya viruses, particularly because these viruses are currently causing a negative impact on public health and economic damage around the world.

Rabies disease dynamics in naïve dog populations in Australia

Currently, Australia is free from terrestrial rabies but an incursion from nearby Indonesia, where the virus is endemic, is a feasible threat. Here, we aimed to determine whether the response to a simulated rabies incursion would vary between three extant Australian dog populations; free-roaming domestic dogs from a remote indigenous community in northern Australia, and free-roaming domestic and wild dogs in peri-urban areas of north-east New South Wales. We further sought to predict how different management strategies impacted disease dynamics in these populations. We used simple stochastic state-transition models and dog demographic and contact rate data from the three dog populations to simulate rabies spread, and used global and local sensitivity analyses to determine effects of model parameters. To identify the most effective control options, dog removal and vaccination strategies were also simulated. Responses to simulated rabies incursions varied between the dog populations. Free-roaming domestic dogs from north-east New South Wales exhibited the lowest risk for rabies maintenance and spread. Due to low containment and high contact rates, rabies progressed rapidly through free-roaming dogs from the remote indigenous community in northern Australia. In contrast, rabies remained at relatively low levels within the north-east New South Wales wild dog population for over a year prior to an epidemic. Across all scenarios, sensitivity analyses revealed that contact rates and the probability of transmission were the most important drivers of the number of infectious individuals within a population. The number of infectious individuals was less sensitive to birth and death rates. Removal of dogs as a control strategy was not effective for any population modelled, while vaccination rates in excess of 70% of the population resulted in significant reductions in disease progression. The variability in response between these distinct dog groups to a rabies incursion, suggests that a blanket approach to management would not be effective or feasible to control rabies in Australia. Control strategies that take into account the different population and behavioural characteristics of these dog groups will maximise the likelihood of effective and efficient rabies control in Australia.

Emerging Viral Zoonoses from Wildlife Associated with Animal-Based Food Systems: Risks and Opportunities

Zoonotic viruses of wildlife origin have caused the majority of recent emerging infectious diseases (EIDs) that have had significant impacts on human health or economies. Animal consumption-based food systems, ranging from the harvest of free-ranging wild species (hereafter, wild harvest systems) to the in situ stocking of domestic or farmed wild animals (hereafter, animal production systems), have been implicated in the emergence of many of these viruses, including HIV, Ebola, SARS, and highly pathogenic avian influenza (HPAI).

Global biogeography of human infectious diseases

The distributions of most infectious agents causing disease in humans are poorly resolved or unknown. However, poorly known and unknown agents contribute to the global burden of disease and will underlie many future disease risks. Existing patterns of infectious disease co-occurrence could thus play a critical role in resolving or anticipating current and future disease threats. We analyzed the global occurrence patterns of 187 human infectious diseases across 225 countries and seven epidemiological classes (human-specific, zoonotic, vector-borne, non-vector-borne, bacterial, viral, and parasitic) to show that human infectious diseases exhibit distinct spatial grouping patterns at a global scale. We demonstrate, using outbreaks of Ebola virus as a test case, that this spatial structuring provides an untapped source of prior information that could be used to tighten the focus of a range of health-related research and management activities at early stages or in data-poor settings, including disease surveillance, outbreak responses, or optimizing pathogen discovery. In examining the correlates of these spatial patterns, among a range of geographic, epidemiological, environmental, and social factors, mammalian biodiversity was the strongest predictor of infectious disease co-occurrence overall and for six of the seven disease classes examined, giving rise to a striking congruence between global pathogeographic and "Wallacean" zoogeographic patterns. This clear biogeographic signal suggests that infectious disease assemblages remain fundamentally constrained in their distributions by ecological barriers to dispersal or establishment, despite the homogenizing forces of globalization. Pathogeography thus provides an overarching context in which other factors promoting infectious disease emergence and spread are set.

Roaming behaviour and home range estimation of domestic dogs in Aboriginal and Torres Strait Islander communities in northern Australia using four different methods

Disease transmission parameters are the core of epidemic models, but are difficult to estimate, especially in the absence of outbreak data. Investigation of the roaming behaviour, home range (HR) and utilization distribution (UD) can provide the foundation for such parameter estimation in free-ranging animals. The objectives of this study were to estimate HR and UD of 69 domestic dogs in six Aboriginal and Torres Strait Islander communities in northern Australia and to compare four different methods (the minimum convex polygon, MCP; the location-based kernel density estimation, LKDE; the biased random bridge, BRB; and Time Local Convex Hull, T-LoCoH) for investigation of UD and estimating HR sizes. Global positioning system (GPS) collars were attached to community dogs for a period of 1-3 days and positions (fixes) were recorded every minute. Median core HRs (50% isopleth) of the 69 dogs were estimated to range from 0.2 to 0.4 ha and the more extended HR (95% isopleth) to range from 2.5 to 5.3 ha, depending on the method used. The HR and UD shapes were found to be generally circular around the dog owner's house. However, some individuals were found to roam much more with a HR size of 40-104 ha and cover large areas of their community or occasionally beyond. These far roaming dogs are of particular interest for infectious disease transmission. Occasionally, dogs were taken between communities and out of communities for hunting, which enables the contact of dogs between communities and with wildlife (such as dingoes). The BRB and T-LoCoH are the only two methods applied here which integrate the consecutiveness of GPS locations into the analysis, a substantial advantage. The recently developed BRB method produced significantly larger HR estimates than the other two methods; however, the variability of HR sizes was lower compared to the other methods. Advantages of the BRB method include a more realistic analytical approach (kernel density estimation based on movements rather than on locations), possibilities to deal with irregular time periods between consecutive GPS fixes and parameter specification which respects the characteristics of the GPS unit used to collect the data. The BRB method was therefore the most suitable method for UD estimation in this dataset. The results of this study can further be used to contact rates between the dogs within and between communities, a foundation for estimating transmission parameters for canine infectious disease models, such as a rabies spread model in Australia.

Emerging infectious diseases in free-ranging wildlife-Australian zoo based wildlife hospitals contribute to national surveillance

Emerging infectious diseases are increasingly originating from wildlife. Many of these diseases have significant impacts on human health, domestic animal health, and biodiversity. Surveillance is the key to early detection of emerging diseases. A zoo based wildlife disease surveillance program developed in Australia incorporates disease information from free-ranging wildlife into the existing national wildlife health information system. This program uses a collaborative approach and provides a strong model for a disease surveillance program for free-ranging wildlife that enhances the national capacity for early detection of emerging diseases.

Ecological Approaches to Studying Zoonoses

Concern over emerging infectious diseases (EIDs) and a better understanding of their causes has resulted in increasing recognition of the linkages among human, animal, and ecosystem health. It is now well recognized that human activities can promote the emergence of infectious diseases through the large-scale modification of natural environments and inadvertent vectoring (e.g., international trade and travel). These perturbations can alter the ecological and evolutionary relationships among humans, wildlife, and the pathogens that move between them, resulting in disease emergence. In recent years, the rise in zoonotic EIDs has not only increased our awareness of the need for cross-sectoral collaborations, but has also highlighted the disconnect between current ecological theory and biological reality. As the One Health movement continues to gain steam, further integration of ecological approaches into the One Health framework will be required. We discuss the importance of ecological methods and theory to the study of zoonotic diseases by (i) discussing key ecological concepts and approaches, (ii) reviewing methods of studying wildlife diseases and their potential applications for zoonoses, and (iii) identifying future directions in the One Health movement.

Human ecology in pathogenic landscapes: two hypotheses on how land use change drives viral emergence

The emergence of novel viral diseases is driven by socioeconomic, demographic and environmental changes. These include land use changes such as deforestation, agricultural expansion and habitat degradation. However, the links between land use change and disease emergence are poorly understood and probably complex. In this review, we propose two hypotheses for the mechanisms by which land use change can lead to viral emergence: firstly, by perturbing disease dynamics in multihost disease systems via impacts on cross-species transmission rates (the 'perturbation' hypothesis); and secondly, by allowing exposure of novel hosts to a rich pool of pathogen diversity (the 'pathogen pool' hypothesis). We discuss ways by which these two hypotheses might be tested using a combination of ecological and virological approaches, and how this may provide novel control and prevention strategies.