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Learn differentiating natural vs. artificial events, detecting pathogens, and selecting appropriate detection equipment. Explore techniques, requirements, and field screening. Make informed decisions!
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STRATEGIES FOR THE DETECTION OF UNKNOWN BIOLOGICAL AGENTS Dr. Peter J. Stopa US Army Edgewood Chemical Biological Center Aberdeen Proving Ground, MD
OBJECTIVES FOR UNKNOWNS DETECTION • Differentiate between natural and artificial events. • Implement and maintain protective postures. • Confirm whether forces have been attacked. • Initiate treatment in the absence of a specific biological agent hazard.
Potential Classification Parameters Bio/non-Bio Aerosol Additives Classify Natural vs. Man-made Pathogen/non-Pathogen Bacteria Virus Protein Peptide Toxin Encapsulants Non-Protein Toxin
Determination of Appropriate Equipment • How do you determine what you need? • Need to identify: • The end user. • How they operate. • Constraints. • Performance Criteria. • How important are each of these factors in determining the best equipment?) (Weighting Factors)
A Computer-based Approach • Can identify each of the parameters and subsequent weighting factors and plug them into a statistical model. • Identify appropriate candidate technologies and score them according to your criteria. • Obtain the final results. • See how they fared and why. • Make purchasing decisions.
Biological Detection • More difficult than chemical. • No vapor pressure – sampling for detection is more difficult. • Present in low concentrations. • May be hard to discriminate an intentional release against background levels of similar “natural” biological materials. • Technologies not as mature. • Clinical personnel sometimes do not understand “the field”. • Most confirmatory technologies are slow (i.e., culture). • Microbiologists are reluctant to adopt instrumented methods (need to see it or smell it to believe it).
Biological Detection Process • Collect samples • Chemical Property Characterization • Generic detection • Biological agent characteristics • Specific identification • Identification kits • Reference laboratory
Chemical Properties From July/August 2003 Homeland First Response
Chemical Properties • Premise: • Biological materials can be viable only within a pH range of 5-9. • Turbidity and density in water may give an indication of particle size and solubility. • Presence of Protein may indicate a biological agent. From July/August 2003 Homeland First Response
WHY GENERIC DETECTION? • Rapidly provide the Incident Commander enough information to justify the response to a suspected biological terrorist threat. • Minimize response resources to false threats. • Evaluate if the sample can be further analyzed with immunoassay tickets on site or sent to a laboratory for confirmation. • Should not rely on immunoassay tickets alone. • Limited library - some materials that a terrorist may use are not on the threat list. • For ticket results to be valid, the sample must be within certain concentration, pH, and ionic strength guidelines.
Biological Properties • Generic detectors that detect biological properties are relatively rapid, inexpensive, and easy to use. • More information than the chemical property test alone –i.e., is it LIVE? • Confirmatory identification must be performed in the laboratory.
Generic Detection Strategy • Use various properties to detect the presence of a biological material in a suspect sample. • Luminescence – ATP – viability (cell battery). • DNA – present in all biological materials. (blueprint). • Protein – also present in all biological materials. (building block). • Particle size/concentration.
Biological Detection Instruments • Particle analyzer • Fluorometer (DNA) • Luminometer (ATP) • Colorimeter (protein) Fluorometer Particle Analyzer Colorimeter Luminometers Integrated System
Expected Results for Generic Detection (1) Possibly from culture media. (2) If protein concentration is high enough (> 10 ug/ml), will probably see contaminating DNA from protein source.
Identification Field Instruments (PCR) Immunoassay Tickets And Readers Biological Laboratory
Comments • Experience from Fall 2001 showed that no single technology was 100% accurate. • Both IA platforms and PCR platforms missed samples for various reasons. • Culture was able to detect in all of the samples – but TOO slow to be of value in the field. • Need redundant capabilities.
CONCLUSIONS • Tests and equipment exist for use by first responders for field screening of biological samples. • Additional discussion is needed among the policy makers, field responders, and reference laboratories to develop or accept a workable system.