Updating a B. anthracis Risk Model with Field Data from a Bioterrorism Incident

Area of Science:

• Environmental science
• Epidemiology
• Bayesian statistics

Background:

• Understanding pathogen spread indoors is crucial for public health.
• The 2001 anthrax attacks highlighted the need for accurate indoor pathogen transport models.

Purpose of the Study:

• To update a model of pathogen fate and transport using real-world anthrax spore data.
• To reduce uncertainty in model parameters and estimate mortality risk.

Main Methods:

• Applied a Bayesian framework and Markov chain Monte Carlo (MCMC) methods.
• Updated model parameters by comparing predictions with measurements from the 2001 anthrax attacks.
• Conducted multivariate sensitivity analyses to assess measurement effectiveness.

Main Results:

• Significantly reduced uncertainty for spore release quantity, room exit amount, and occupant risk.
• Found prior literature estimates for deposition and resuspension rates were consistent with observed data.
• Estimated posterior mortality risk between 0.01 and 0.1, supporting prophylactic antibiotic administration.

Conclusions:

• Bayesian updating effectively refined indoor pathogen transport models.
• Accurate risk assessment is vital for public health interventions like antibiotic prophylaxis.
• Environmental sampling strategies should be tailored based on knowledge of released particulate size distribution.