ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

EpidemiologyFurthermore, in the era of biological weapons useby individuals, organizations, and governments,epidemiological studies of the effect of exposure to infectiousmicrobes has become more urgently important.Knowledge of the effect of a bioweapon on the battlefieldmay not extend to the civilian population that might alsobe secondarily affected by the weapons. Thus, epidemiologyis an important tool in identifying and tracing thecourse of an infection.Molecular and genetic basis of epidemiology. Geneticepidemiology studies could result in data that would enableforensic investigators to rapidly identify bioterrorismor biological warfare agents specifically engineered orvectored to affect certain subgroups within a largerpopulation.Molecular epidemiology arises from varied scientificdisciplines, including genetics, epidemiology and statistics.The strategies involved in genetic epidemiology encompasspopulation studies and family studies. Sophisticatedmathematical tools are now involved, and computertechnology is playing a predominant role in the developmentof the discipline. Multidisciplinary collaboration iscrucial to understanding the role of genetic and environmentalfactors in disease processes.Much information can come from molecular epidemiologyeven if the exact genetic cause of the malady is notknown. For example, the identification of a malady ingenerations of related people can trace the genetic characteristic,and even help identify the original source of thetrait. This approach is commonly referred to as geneticscreening. The knowledge of why a particular maladyappears in certain people, or why such people are moreprone to a microbial infection than other members of thepopulation, can reveal much about the nature of the diseasein the absence of the actual gene whose defectcauses the disease.Differences in response to pathogens is often a complexinterplay of various environmental and genetic factorsthat require sophisticated analytical tools and techniquesto identify. Aided by advances in computertechnology, scientists develop complex mathematical formulasfor the analysis of epidemiological models, thedescription of the transmission of the disease, and genetic-environmentalinteractions. Sophisticated mathematicaltechniques are now used for assessing classification,diagnosis, prognosis and treatment of many diseases.Population studies provide data that greatly impactpublic health programs and emergency responses. Bymeans of several statistical tools, genetic epidemiologicstudies evaluate risk factors, inheritance and possiblemodels of inheritance. Different kinds of studies are basedupon the number of people who participate and the methodof sample collection (i.e., at the time of an outbreak or afteran outbreak has occurred). A challenge for the investigatoris to achieve a result able to be applied with as low a biasas possible to the general population. In other words, thegoal of an epidemiological study of an infectious outbreakis to make the results from a few individuals applicable tothe whole population.A fundamental underpinning of infectious epidemiologyis the confirmation that a disease outbreak hasoccurred. Once this is done, the disease is followed withtime. The pattern of appearance of cases of the diseasecan be tracked by developing what is known as an epidemiccurve. This information is vital in distinguishing anatural outbreak from a deliberate and hostile act, forexample. In a natural outbreak the number of cases increasesover time to a peak, after which the cases subsideas immunity develops in the population. A deliberaterelease of organisms will be evident as a sudden appearanceof a large number of cases at the same time.Tracking diseases with technology. Many illnesses ofepidemiological concern are caused by microorganisms.Examples include hemorrhagic fevers such as that causedby the Ebola virus. The determination of the nature ofillness outbreaks due to these and other microorganismsinvolve microbiological and immunological techniques.Various routes can spread infections (i.e., contact, airborne, insect borne, food and water intake, etc.). Likewise,the route of entry of an infectious microbe can also varyfrom microbe to microbe.If an outbreak is recognized early enough, samples ofthe suspected cause as well as samples from the afflicted(i.e., sputum, feces) can be gathered for analysis. Theanalysis will depend on the symptoms. For example, inthe case of a food poisoning, symptoms such as the rapiddevelopment of cramping, nausea with vomiting, anddiarrhea after eating a hamburger would be grounds toconsider Escherichia coli O157:H7 as the culprit. Analyseswould likely include the examination for other knownmicrobes associated with food poisoning (i.e., Salmonella)in order to save time in identifying the organism.Analysis can involve the use of conventional laboratorytechniques (e.g., use of nonselective and selectivegrowth media to detect bacteria). As well, more recenttechnological innovations can be employed. An exampleis the use of antibodies to a known microorganism that arecomplexed with a fluorescent particle. The binding of theantibody to the microbes can be detected by the examinationof a sample using fluorescence microscopy or flowcytometry. Molecular techniques such as the polymerasechain reaction are employed to detect genetic materialfrom a target organism. However, the expense of thetechniques such as PCR tends to limit its use to more of aconfirmatory role, rather than as an initial tool of aninvestigation. A considerable research effort is ongoing atU.S. National Laboratories to develop quicker, less expensive,and more portable PCR equipment that can be usedby inspectors and investigators.Another epidemiological tool is the determination ofthe antibiotic susceptibility and resistance of bacteria.412 Encyclopedia of Espionage, Intelligence, and Security