Airborne Infection withBacillus anthracis—from Mills to Mail

Abstract

The lack of identified exposures in 2 of the 11 cases of bioterrorism-related inhalation anthrax in 2001 raised uncertainty about the infectious dose and transmission of Bacillus anthracis. We used the Wells-Riley mathematical model of airborne infection to estimate 1) the exposure concentrations in postal facilities where cases of inhalation anthrax occurred and 2) the risk for infection in various hypothetical scenarios of exposure to B. anthracis aerosolized from contaminated mail in residential settings. These models suggest that a small number of cases of inhalation anthrax can be expected when large numbers of persons are exposed to low concentrations of B. anthracis. The risk for inhalation anthrax is determined not only by bacillary virulence factors but also by infectious aerosol production and removal rates and by host factors.

Prophylaxis after Exposure toCoxiella burnetii

“…These threshold points and PEP recommendations must be useful and realistic. Some research has been conducted to evaluate how to determine likely concentrations of a bioterrorism agent and a person's level of exposure by using computer modeling and simulation (38). Further studies on the assessment of exposure would be benefi cial; modeling Q fever exposure would be especially critical given C. burnetii's low infectious dose and high environmental stability (9).…”

Diagnostic Bioterrorism Response Strategies

“…On October 4, 2001, shortly after 9/11, an inhalation anthrax case was reported in a 63-old male in Florida (Fennelly et al, 2004). Subsequently, additional persons were identified who were infected with B. anthracis.…”

Anthrax Sampling and Decontamination: Technology Trade-Offs

“…Fennelly et al (2004) summarized results from previous analyses of anthrax healtheffects data, and re-analyzed data from an anthrax outbreak in Manchester, England in 1957 for which some exposure data were available. For a virulent strain of anthrax they estimate ID 25 , the dose that will infect 25% of a population, to be 140-690 CFU smaller than 5µm and 620-2200 total CFU.…”

“…There is no good quantitative estimate of their exposure, but it may have been less than 100 spores and perhaps less than 10. One of the women was over 90 years old and the other over 60, so age may have been a factor: there are many reasons the elderly would be expected to be more susceptible (see Fennelly et al 2004, for example).…”