Project Highlights

At MSU, Dr. Syed Hashsham and PhD candidate Amanda Herzog explore critical information for detecting anthrax and viruses in the environment.

The release of Bacillus anthracis through mail envelopes in 2001 highlighted the lack of quantitative information on the methods used for the detection of B. anthracis.  Quantitative risk assessment modeling requires descriptive statistics of the detection limit to assist in defining exposure.  The instrument detection limits and environmental detection limits for methods detecting B. anthracis were reviewed from the literature to determine the most sensitive methods and the parameters that challenge sensitive detection.  The many processing challenges affecting the sensitivity of the environmental detection limit are the challenges that first responders and clean up strategists will experience.  However, there were very few articles on the detection of B. anthracis in soil, air, fomites, and water.  Risk estimates were calculated at the instrument detection limit and environmental detection limit to assess if risk at the detection limit will be acceptable for declaring a site clean.

Quantitative data (survival, inactivation, recovery, transfer ability, etc) on the role fomites play in the transmission of microorganisms is also necessary for the assessment of risk.  Nonporous fomites commonly found in indoor environments (plastic, steel, and laminar) with surface areas of 100 cm2 and 1000 cm2 were inoculated with bacteriophage P22.  The variability in the recovery of P22 as a function of fomite type, surface area, application mediums, relative humidity, wetting agent, sampling techniques and sampling time were evaluated.  Parameters that may affect the recovery of viruses at the detection limit (low concentration and large fomite size) may assist in the environmental sampling during an outbreak and the establishment of cleanup strategies.

Latest CAMRA Publications

Collaboration: Projects I, III, V:
Jones, R.M., Y. Masago, T. A. Bartrand, C. N. Haas, M. Nicas, and J. Rose. 2009 Characterizing the Risk of Infection from Mycobacterium tuberculosis in Commercial Passenger Aircraft using Quantitative Microbial Risk Assessment.  Risk Analysis (In Press) Advanced Online Publication.

Abstract: Quantitative microbial risk assessment was used to predict the likelihood and spatial organization of Mycobacterium tuberculosis (Mtb) transmission in a commercial aircraft. Passenger exposure was predicted via a multizone Markov model in four scenarios: seated or moving infectious passengers and with or without filtration of recirculated cabin air. The traditional exponential (k= 1) and a new exponential (k= 0.0218) dose-response function were used to compute infection risk. Emission variability was included by Monte Carlo simulation. Infection risks were higher nearer and aft of the source; steady state airborne concentration levels were not attained. Expected incidence was low to moderate, with the central 95% ranging from 10−6 to 10−1 per 169 passengers in the four scenarios. Emission rates used were low compared to measurements from active TB patients in wards, thus a "superspreader" emitting 44 quanta/h could produce 6.2 cases or more under these scenarios. Use of respiratory protection by the infectious source and/or susceptible passengers reduced infection incidence up to one order of magnitude.

Project IV:
Casman, E. A. and B. Fischhoff. 2008. Risk Communication Planning for the Aftermath of a Plague Bioattack. Risk Analysis 28(5):1327-1342.

Abstract: We create an influence diagram of how a plague bioattack could unfold and then use it to identify factors shaping infection risks in many possible scenarios. The influence diagram and associated explanations provide a compact reference that allows risk communicators to identify key messages for pre-event preparation and testing. It can also be used to answer specific questions in whatever unique situations arise, considering both the conditions of the attack and the properties of the attacked populations. The influence diagram allows a quick, visual check of the factors that must be covered when evaluating audience information needs. The documentation provides content for explaining the resultant advice. We show how these tools can help in preparing for crises and responding to them.

Project I:
Masago, Y., T. Shibata, and J. B. Rose. 2008. Bacteriophage P22 and Staphylococcus aureus Attenuation on Nonporous Fomites as Determined by Plate Assay and Quantitative PCR. Applied and Environmental Microbiology 74(18):5838-5840.

Abstract: Decay rates of bacteriophage P22 and Staphylococcus aureus on six types of common household inanimate surfaces were evaluated based on cultivation and quantitative PCR. A much higher level of inactivation was observed using the plate assay, suggesting that detection of the pathogen genome in samples from fomites does not necessarily imply a health risk to humans.