Risk‐Based Decision Making for Reoccupation of Contaminated Areas Following a Wide‐Area Anthrax Release

Abstract

This article presents an analysis of postattack response strategies to mitigate the risks of reoccupying contaminated areas following a release of Bacillus anthracis spores (the bacterium responsible for causing anthrax) in an urban setting. The analysis is based on a hypothetical attack scenario in which individuals are exposed to B. anthracis spores during an initial aerosol release and then placed on prophylactic antibiotics that successfully protect them against the initial aerosol exposure. The risk from reoccupying buildings contaminated with spores due to their reaerosolization and inhalation is then evaluated. The response options considered include: decontamination of the buildings, vaccination of individuals reoccupying the buildings, extended evacuation of individuals from the contaminated buildings, and combinations of these options. The study uses a decision tree to estimate the costs and benefits of alternative response strategies across a range of exposure risks. Results for best estimates of model inputs suggest that the most cost-effective response for high-risk scenarios (individual chance of infection exceeding 11%) consists of evacuation and building decontamination. For infection risks between 4% and 11%, the preferred option is to evacuate for a short period, vaccinate, and then reoccupy once the vaccine has taken effect. For risks between 0.003% and 4%, the preferred option is to vaccinate only. For risks below 0.003%, none of the mitigation actions have positive expected monetary benefits. A sensitivity analysis indicates that for high-infection-likelihood scenarios, vaccination is recommended in the case where decontamination efficacy is less than 99.99%.

Reverse QMRA as a Decision Support Tool: Setting Acceptable Concentration Limits for Pseudomonas aeruginosa and Naegleria fowleri

“…The concentrations of P. aeruginosa and N. fowleri in water samples can be determined using microbiological analyses, and then the QMRA-based critical concentrations can be used in interpreting the results of microbial analyses and provide guidance on what concentrations may be considered tolerable (i.e., acceptable risks) and what action levels are required. This process of calculating the critical microbial concentration based on the critical level of risk is referred to as the "reverse QMRA" approach [6,34,35].…”

A Risk Analysis Framework for Prioritizing and Managing Biosecurity Threats

“…In this context, risk analysts may consider the reduction of impacts that a risk mitigation action generates against implementation costs. In other instances, an expected monetary value can be employed as a metric to compare the different response alternatives, such as the analysis by Hamilton et al (2015) to plan the reoccupation of a wide area contaminated by Anthrax.…”

“…An illustration of this type of analysis is the model developed by Mohtadi and Murshid (2009) to estimate the likelihood of a bioweapon attack and potential number of causalities from a large‐scale chemical, biological, or radionuclear threat. A second approach is to employ a decision tree to estimate the possible consequences of coping with a biosecurity threat, as in the model developed by Hamilton, Hong, Casman, and Gurian (2015) to identify the best option to reoccupy an area contaminated by anthrax considering their expected monetized impact. A third way is to model the uncertainty associated with the impacts of an outbreak caused by a biosecurity threat and develop transmission models to predict its spread (Lindgren, 2012; Stohlgren & Schnase, 2006).…”

Dose‐Response Modeling for Inhalational Anthrax in Rabbits Following Single or Multiple Exposures

“…Since then, much research has been conducted and our understanding of the disease has improved significantly. However, one gap that remains is the ability to characterize the risk of disease following inhalation of a low dose of spores . Several low‐dose exposure scenarios are relevant to an aerosol attack with B. anthracis spores.…”

“…However, one gap that remains is the ability to characterize the risk of disease following inhalation of a low dose of spores. (7)(8)(9)(10)(11)(12)(13)(14)(15)(16) Several lowdose exposure scenarios are relevant to an aerosol attack with B. anthracis spores. One exposure scenario would be inhaling a single dose of spores within a short period of time (approximately 10-15 minutes), which would reflect an acute exposure that might be encountered during an attack.…”