Analysis of CDC social control measures using an agent-based simulation of an influenza epidemic in a city

Background: the transmission of infectious disease amongst the human population is a complex process which requires advanced, often individual-based, models to capture the space-time details observed in reality.Methods: an Individual Space-Time Activity-based Model (ISTAM) was applied to simulate the effectiveness of non-pharmaceutical control measures including: (1) refraining from social activities, (2) school closure and (3) household quarantine, for a hypothetical influenza outbreak in an urban area.Results: amongst the set of control measures tested, refraining from social activities with various compliance levels was relatively ineffective. Household quarantine was very effective, especially for the peak number of cases and total number of cases, with large differences between compliance levels. Household quarantine resulted in a decrease in the peak number of cases from more than 300 to around 158 for a 100% compliance level, a decrease of about 48.7%. The delay in the outbreak peak was about 3 to 17 days. The total number of cases decreased to a range of 3635-5403, that is, 63.7%-94.7% of the baseline value.When coupling control measures, household quarantine together with school closure was the most effective strategy. The resulting space-time distribution of infection in different classes of activity bundles (AB) suggests that the epidemic outbreak is strengthened amongst children and then spread to adults. By sensitivity analysis, this study demonstrated that earlier implementation of control measures leads to greater efficacy. Also, for infectious diseases with larger basic reproduction number, the effectiveness of non-pharmaceutical measures was shown to be limited.Conclusions: simulated results showed that household quarantine was the most effective control measure, while school closure and household quarantine implemented together achieved the greatest benefit. Agent-based models should be applied in the future to evaluate the efficacy of control measures for a range of disease outbreaks in a range of settings given sufficient information about the given case and knowledge about the transmission processes at a fine scal

Data on face-to-face contacts in an office building suggests a low-cost vaccination strategy based on community linkers

Empirical data on contacts between individuals in social contexts play an important role in providing information for models describing human behavior and how epidemics spread in populations. Here, we analyze data on face-to-face contacts collected in an office building. The statistical properties of contacts are similar to other social situations, but important differences are observed in the contact network structure. In particular, the contact network is strongly shaped by the organization of the offices in departments, which has consequences in the design of accurate agent-based models of epidemic spread. We consider the contact network as a potential substrate for infectious disease spread and show that its sparsity tends to prevent outbreaks of rapidly spreading epidemics. Moreover, we define three typical behaviors according to the fraction $f$ of links each individual shares outside its own department: residents, wanderers and linkers. Linkers ($f\sim 50\%$) act as bridges in the network and have large betweenness centralities. Thus, a vaccination strategy targeting linkers efficiently prevents large outbreaks. As such a behavior may be spotted a priori in the offices' organization or from surveys, without the full knowledge of the time-resolved contact network, this result may help the design of efficient, low-cost vaccination or social-distancing strategies

The effectiveness of policies to control a human influenza pandemic : a literature review

The studies reviewed in this paper indicate that with adequate preparedness planning and execution it is possible to contain pandemic influenza outbreaks where they occur, for viral strains of moderate infectiousness. For viral strains of higher infectiousness, containment may be difficult, but it may be possible to mitigate the effects of the spread of pandemic influenza within a country and/or internationally with a combination of policies suited to the origins and nature of the initial outbreak. These results indicate the likelihood of containment success in'frontline risk'countries, given specific resource availability and level of infectiousness; as well as mitigation success in'secondary'risk countries, given the assumption of inevitable international transmission through air travel networks. However, from the analysis of the modeling results on interventions in the U.S. and U.K. after a global pandemic starts, there is a basis for arguing that the emphasis in the secondary risk countries could shift from mitigation towards containment. This follows since a mitigation-focused strategy in such developed countries presupposes that initial outbreak containment in these countries will necessarily fail. This is paradoxical if containment success at similar infectiousness of the virus is likely in developing countries with lower public health resources, based on results using similar modeling methodologies. Such a shift in emphasis could have major implications for global risk management for diseases of international concern such as pandemic influenza or a SARS-like disease.Avian Flu,Disease Control&Prevention,Health Monitoring&Evaluation,Population Policies,HIV AIDS

Analysis of Control Measures Used During Cholera Outbreaks Among Internally Displaced Persons

Cholera remains a major public health problem affecting high-risk populations such as camps of internally displaced persons. During a cholera outbreak, it is essential to reduce transmission and minimize new infections. The Miasma theory, host-agent-environment model and Ecosocial theory were utilized for this study. This study was a retrospective comparison to determine whether historical cholera control measures are effective during current cholera outbreaks within camps of internally displaced persons. A quantitative approach ascertained changes in incidence and mortality rates following implementation of primary and/or secondary control measures. Cholera outbreaks were identified from the World Health Organization\u27s (WHO) Disease Outbreak News reports issued between 1996 and 2017. Each reported cholera outbreak was categorized into one of eight outbreak cohorts -- each cohort having the same primary control measure. The WHO Data Repository was used to identify cholera incidence and/or mortalities and the World Bank data set was used for population total to calculate incidence and/or mortality rates for the years prior to and the year of the outbreak to calculate the case percentage change and death percentage change. Analysis of covariance was used to assess statistical significance in rate change within each intervention cohort. No statistical significance was noted within various cholera control intervention. Limitations of this study provide the basis for continued research on this topic; also aligning with the Global Task Force on Cholera to reduce infections by 90% by the year 2030

Lawrence O. Gostin on Biosecurity Policy: Are We Safer Today?

World-acclaimed authority Lawrence O. Gostin analyzes biosecurity policy since 9/11. He begins with the question: Are we safer now? Then comes a review of biosecurity legislation, followed by discussion of planning to deal with specific diseases and the problems with such an approach, and then an explanation of what the right approach is. He concludes by covering the Model State Emergency Health Powers Act and related civil liberties questions

Event-based surveillance during EXPO Milan 2015. Rationale, tools, procedures, and initial results

More than 21 million participants attended EXPO Milan from May to October 2015, making it one of the largest protracted mass gathering events in Europe. Given the expected national and international population movement and health security issues associated with this event, Italy fully implemented, for the first time, an event-based surveillance (EBS) system focusing on naturally occurring infectious diseases and the monitoring of biological agents with potential for intentional release. The system started its pilot phase in March 2015 and was fully operational between April and November 2015. In order to set the specific objectives of the EBS system, and its complementary role to indicator-based surveillance, we defined a list of priority diseases and conditions. This list was designed on the basis of the probability and possible public health impact of infectious disease transmission, existing statutory surveillance systems in place, and any surveillance enhancements during the mass gathering event. This article reports the methodology used to design the EBS system for EXPO Milan and the results of 8 months of surveillance

Biological Terrorism, Emerging Diseases, and National Security

Examines the extent to which bioterrorist attacks have proven or may prove difficult to distinguish from outbreaks of emerging diseases. Makes recommendations for how the U.S. could better prepare to meet the threat of biological terrorism

Technical handbook for dengue surveillance, dengue outbreak prediction/detection and outbreak response (Model contingency plan)

This handbook was produced by TDR together with WHO’s Neglected Tropical Diseases (NTD) Department and WHO regional offices in the context of a European Union-financed research programme, the International Research Consortium on Dengue Risk Assessment, Management and Surveillance (IDAMS), to develop an evidence-based handbook for the early outbreak detec-tion and management of dengue fever outbreaks. The handbook targets public health providers, in particular those at national level. It is not an implementation guideline, but a framework for developing a national contingency plan with local adaptations that acknowledge micro-level pro-gramme components. Response planning requires contextual details encompassing the structure of the health and vector control services, the availability of infrastructure and budget, and human resources, and the willingness of staff to cooperate, among others. The aim of this “model contingency plan” is to assist programme managers and planners in devel-oping a national, context-specific, dengue outbreak response plan in order to: (a) detect a dengue outbreak at an early stage through clearly defined and validated alarm signals; (b) precisely define when a dengue outbreak has started; and (c) organize an early response to the alarm signals or an “emergency response” once an outbreak has started. A summary of this document, "Dengue Contingency Planning: From Research to Policy and Practice" (PNTD-D-16-00407R1) has also been published in PLOS Neglected Tropical Diseases

PROCESS SYSTEMS ENGINEERING APPROACHES FOR INTERVENTION PLANNING DURING INFECTIOUS DISEASE OUTBREAKS

Ph.DDOCTOR OF PHILOSOPH