Results from laboratory testing are an important source of information for biosurveillance systems. Clinical laboratory tests are vital for the correct diagnosis and treatment of individuals. Clinical laboratories analyze blood, urine, mucus, saliva, respiratory secretions, cerebrospinal fluid, semen, vaginal secretions, sweat, feces, fluid aspirated from joints, and tissues from humans and animals. The tests performed include cell counts; analytical chemistries, including drug and toxin tests; and examinations to detect and identify microbes and markers of current and past infection. Environmental testing is critical to the detection of outbreaks, the prevention of disease, and the monitoring of the environment. Environmental laboratories analyze samples of water, food, air, soil, plant material, and unknown powders, as well as samples taken from surfaces for evidence of bacterial, viral, toxin, or chemical contamination.

Data produced by laboratories are important for biosurveillance of virtually every disease caused by biological agents, chemicals, or toxins. Data collected during the preanalytical, analytical, and postanalytical phases of testing can be captured and incorporated directly into biosurveillance systems. Preanalytical data, such as the type of test ordered and the reason for a test, can provide an early clue to the existence of an outbreak. Similarly, analytic results, such as the initial Gram stain of a cerebrospinal fluid specimen, can potentially confirm a diagnosis when combined with other clinical information, as it did in the first case of inhalational anthrax in the 2001 postal attack. The actual results of tests are obviously foundational to biosurveillance.

The range of tests offered by an individual laboratory varies significantly among laboratories in the United States. Many small laboratories perform a limited number of tests that are needed on an urgent basis or for screening purposes. Larger laboratories provide more complex confirmatory analyses. The majority of clinical laboratories in the United States are small laboratories located in physician offices; however, the larger laboratories account for a high volume of all tests performed.

Table 8.1 describes the clinical laboratory tests that contribute to the diagnosis of inhalational anthrax. Anthrax, as well as many other infectious diseases, is diagnosed after the performance of presumptive and confirmatory tests in combination with the clinical presentation. Clinical specimens, such as blood, cere-brospinal fluid, urine, sputum, throat swabs, and skin scrapings, are used to isolate a causative agent that is later subjected to further testing with confirmatory procedures to make the final identification. Preliminary tests results are sometimes released before the confirmatory tests results become available. When preliminary results are reported, the report often contains a statement about when final results will be available.

Laboratories that produce the types of data most useful for biosurveillance include clinical laboratories operated by the human or animal health systems, commercial laboratories, and governmental laboratories. Laboratories typically specialize in either human or animal testing. Commercial laboratories are free-standing laboratories that are not associated with hospitals or healthcare facilities and that often provide a broad range of services over a wide geographical area. Governmental laboratories exist at the federal, state, and local level and often provide testing that is not readily available from other laboratories. We describe each of these types of laboratories in this chapter.

Laboratories that test for biologic agents are classified as biosafety level 1,2,3, or 4, with biosafety level 4 providing the highest degree of protection to personnel and the environment. Most clinical laboratory work is performed at level 2. These biosafety levels combine the use of laboratory safety practices, safety equipment, and laboratory facilities to provide greater levels of safety for the more dangerous organisms. Each level is specifically appropriate for handling various biologic agents (CDC, 1999).

Was this article helpful?

0 0

Post a comment