Use of sentinel laboratories by clinicians to evaluate potential bioterrorism and emerging infections

Abstract

With the persistent threat of emerging infectious diseases and bioterrorism, it has become increasingly important that clinicians be able to identify the diseases that might signal the occurrence of these unusual events. Essential to a thoughtful diagnostic approach is understanding when to initiate a public health investigation and how to appropriately use commonly performed microbiology procedures in the sentinel laboratory to evaluate potential pathogens. Although diagnostic test development is evolving rapidly, recognizing many of these pathogens continues to challenge the capabilities of most sentinel laboratories. Therefore, effective, ongoing communication and education among clinicians, infection control personnel, sentinel laboratorians, public health authorities, and Laboratory Response Network reference laboratorians is the key to preparedness.

Table 1

Specimen collection guidelines listed by bacteria, toxins, and viruses.

Figure 1

Sample algorithm illustrating the approach to a hypothetical cluster of acute febrile respiratory illnesses with epidemiological links to severe acute respiratory syndrome (SARS) or avian influenza. BSL-3, biosafety level—3; CAP, community-acquired pneumonia; DFA, direct fluorescent antibody stain; NP, nasopharyngeal; PH, public health; SEB, staphylococcal enterotoxin B. Adapted from [16, 17].

Figure 2

Sample algorithm illustrating the approach to a hypothetical patient with an acute generalized febrile vesicular rash. BSL-2, biosafety—level 2; DFA, direct fluorescent antibody stain; EM, electron microscopy; HSV, herpes simplex virus; ID, infectious diseases; PH, public health; VZV, varicella-zoster virus. Adapted from [50].

Table 2

Clinical and microbiological characteristics listed by bacteria, toxins, and viruses.

Figure 3

Electron microscopy of negatively stained viruses. A, Viruses in the Orthopox genus (e.g., variola, vaccinia, monkeypox) and viruses in the Molluscipox genus (e.g., molluscum contagiosum) are morphologically similar. They are large, brick-shaped particles, ∼200 nm × 250–300 nm in size. Depending on the number and configuration of membranes around the particles, the surfaces may appear somewhat rough or with deep ridges. B, Parapox viruses (e.g., orf and Milker nodule virus) are slimmer and more elongated, 140–170 nm × 220–300 nm in size. The surface of these viruses frequently appears to have criss-crossed striations, like rope wrapped diagonally around the particle. C, Herpesviruses (e.g., varicella-zoster virus, human herpes virus, or herpes simplex virus) are 120–200 nm in diameter, with icosahedral nucleocapsids of ∼100 nm in diameter. Smallpox or variola can be rapidly (in 10–20 min) and easily distinguished morphologically from herpesviruses and parapoxviruses by negatively staining vesicle fluid. Electron photomicrograph is courtesy of Dr. Sara E. Miller.