Modeling Tool for Decision Support during Early Days of an Anthrax Event

Mathematical models and analysis tools for risk assessment of unnatural epidemics: a scoping review

Predicting, issuing early warnings, and assessing risks associated with unnatural epidemics (UEs) present significant challenges. These tasks also represent key areas of focus within the field of prevention and control research for UEs. A scoping review was conducted using databases such as PubMed, Web of Science, Scopus, and Embase, from inception to 31 December 2023. Sixty-six studies met the inclusion criteria. Two types of models (data-driven and mechanistic-based models) and a class of analysis tools for risk assessment of UEs were identified. The validation part of models involved calibration, improvement, and comparison. Three surveillance systems (event-based, indicator-based, and hybrid) were reported for monitoring UEs. In the current study, mathematical models and analysis tools suggest a distinction between natural epidemics and UEs in selecting model parameters and warning thresholds. Future research should consider combining a mechanistic-based model with a data-driven model and learning to pursue time-varying, high-precision risk assessment capabilities.

Modeling on the Effects of Deliberate Release of Aerosolized Inhalational Bacillus anthracis (Anthrax) on an Australian Population

This study aimed to determine optimal mitigation strategies in the event of an aerosolized attack with Bacillus anthracis, a category A bioterrorism agent with a case fatality rate of nearly 100% if inhaled and untreated. To simulate the effect of an anthrax attack, we used a plume dispersion model for Sydney, Australia, accounting for weather conditions. We determined the radius of exposure in different sizes of attack scenarios by spore quantity released per second. Estimations of different spore concentrations were then used to calculate the exposed population to inform a Susceptible-Exposed-Infected-Recovered (SEIR) deterministic mathematical model. Results are shown as estimates of the total number of exposed and infected people, along with the burden of disease, to quantify the amount of vaccination and antibiotics doses needed for stockpiles. For the worst-case scenario, over 500,000 people could be exposed and over 300,000 infected. The number of deaths depends closely on timing to start postexposure prophylaxis. Vaccination used as a postexposure prophylaxis in conjunction with antibiotics is the most effective mitigation strategy to reduce deaths after an aerosolized attack and is more effective when the response starts early (2 days after release) and has high adherence, while it makes only a small difference when started late (after 10 days).

Systematic Review and Evaluation of Mathematical Attack Models of Human Inhalational Anthrax for Supporting Public Health Decision Making and Response

BACKGROUND

Anthrax is a potential biological weapon and can be used in an air-borne or mail attack, such as in the attack in the United States in 2001. Planning for such an event requires the best available science. Since large-scale experiments are not feasible, mathematical modelling is a crucial tool to inform planning. The aim of this study is to systematically review and evaluate the approaches to mathematical modelling of inhalational anthrax attack to support public health decision making and response.

METHODS

A systematic review of inhalational anthrax attack models was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. The models were reviewed based on a set of defined criteria, including the inclusion of atmospheric dispersion component and capacity for real-time decision support.

RESULTS

Of 13 mathematical modelling studies of human inhalational anthrax attacks, there were six studies that took atmospheric dispersion of anthrax spores into account. Further, only two modelling studies had potential utility for real-time decision support, and only one model was validated using real data.

CONCLUSION

The limited modelling studies available use widely varying methods, assumptions, and data. Estimation of attack size using different models may be quite different, and is likely to be under-estimated by models which do not consider weather conditions. Validation with available data is crucial and may improve models. Further, there is a need for both complex models that can provide accurate atmospheric dispersion modelling, as well as for simpler modelling tools that provide real-time decision support for epidemic response.

Clinical Management of Patients Infected with Highly Pathogenic Microorganisms

The clinical management of high consequence infectious diseases (HCID) poses an immense challenge, seen largely varying standards in terms of infection prevention control (IPC) as well as in quality of clinical care. This chapter gives an overview of possible treatment as well as IPC options. Lessons learned within the German Permanent Working Group of Competence and Treatment Centres for highly infectious, life-threatening diseases (STAKOB) are taken into account.

Best practice assessment of disease modelling for infectious disease outbreaks

During emerging disease outbreaks, public health, emergency management officials and decision-makers increasingly rely on epidemiological models to forecast outbreak progression and determine the best response to health crisis needs. Outbreak response strategies derived from such modelling may include pharmaceutical distribution, immunisation campaigns, social distancing, prophylactic pharmaceuticals, medical care, bed surge, security and other requirements. Infectious disease modelling estimates are unavoidably subject to multiple interpretations, and full understanding of a model's limitations may be lost when provided from the disease modeller to public health practitioner to government policymaker. We review epidemiological models created for diseases which are of greatest concern for public health protection. Such diseases, whether transmitted from person-to-person (Ebola, influenza, smallpox), via direct exposure (anthrax), or food and waterborne exposure (cholera, typhoid) may cause severe illness and death in a large population. We examine disease-specific models to determine best practices characterising infectious disease outbreaks and facilitating emergency response and implementation of public health policy and disease control measures.

A Calculation Tool and Process to Pre-Position Pharmaceuticals for Anthrax Post-Exposure Prophylaxis

Anthrax, caused by Bacillus anthracis, is considered a severe bioterrorism threat because of its high mortality rate. The Chicago Healthcare System Coalition for Preparedness and Response (CHSCPR) aims to pre-position antibiotic medical countermeasures (MCMs) at healthcare facilities in order to provide on-site anthrax post-exposure prophylaxis. Pharmacists proposed moving toward a new process that involved the development of a standardized calculation methodology for acquiring supply drugs. This was an interventional quality improvement project aimed at optimizing inventory, acquisition, and distribution of antibiotic MCMs for anthrax post-exposure prophylaxis at Chicago hospitals for hospital personnel, associated first responders, and their families. The primary goal of the project was to pre-position a sufficient quantity of pharmaceuticals to allow Chicago hospitals to function as closed points of dispensing (PODs) for 72 hours; a secondary goal was to provide a 96-hour supply of anthrax post-exposure prophylaxis. A total of 35 Chicago hospitals were invited to participate in this intervention study, and 30 hospitals agreed to participate. Based on our calculation tool, we initially identified 6 (20%) hospitals with adequate oral doxycycline and ciprofloxacin inventory to last 72 hours and 3 (10%) hospitals with inventory to last 96 hours as a closed POD for anthrax post-exposure prophylaxis. The necessary quantities of medication needed to establish 72 and 96 hours of anthrax post-exposure prophylaxis were calculated by the CHSCPR and negotiated with a drug wholesaler to obtain product with maximum shelf-life and discounted pricing. Acting as a group purchaser, the CHSCPR organized drop shipment of medication directly to facilities from a wholesaler. This systematically calculated, pre-deployed pharmaceutical cache enhanced availability of antibiotic MCMs for anthrax post-exposure prophylaxis in 30 Chicago hospitals, allowing them to function as closed PODs for 96 hours during an incident.