Assess the Patient
Many if not most of the likely agents to be used for bioterrorism have overlapping incubation
periods and clinical presentations. Where under normal circumstances we could depend on
epidemiology to assist us in narrowing our differential diagnosis, for the initial cases, we must
rely exclusively on a syndromic approach prior to laboratory confirmation. Table 6 (1,5,23–30)
provides a comparison of clinical presentations for Class A agents. Selected Class B and C
agents are discussed in Table 7 (7,8,31–42).
Table 3 Epidemiologic Characteristics of a Bioterrorist Attack
Epidemiologic characteristic Comments and special considerations in a civilian attack
Epidemic of similar disease in a limited
population
The combination of prolonged incubation periods and the
release of an airborne pathogen at a transportation
hub (subway, train, or bus station, or airport) may allow
infected individuals to travel considerable distances
before becoming ill.
Incubation periods Casualties occurring within hours of one another suggest
chemical or toxin.
Casualties presenting over days suggests a biologic
agent.
Characteristics in epidemic curve A sudden rise and fall in the number of cases or a steady
increase in the number of casualties suggests a
biologic agent.
Unexplained increases in morbidity and mortality This may not become apparent early after an attack,
especially in an individual institution. Variations in the
cross section of those exposed to the pathogen: the
most severely affected will be the elderly and those
with common chronic diseases (cardiac and
pulmonary diseases)—those most commonly admitted
to intensive care units.
More severe disease than expected from the
isolated pathogen and failure to respond to
standard recommended therapy
This is often the case with compromised patients who are
admitted to the intensive care unit.Disease that is unusual for a geographic area or
season
Travel and contact history may be difficult to obtain from
patientsin extremis.
Vector-transmitted disease occurring in an area
devoid of the vector
Multiple simultaneous cases of different
infectious diseases in the same population
In a single institution, this may only become apparent
sometime after the initial cases of each disease
present themselves.
A single case of an uncommon disease Examples: All category A pathogens, smallpox (V. major
andV. minor), monkeypox, viral hemorrhagic fevers,
plague, tularemia, or anthrax in any form, brucellosis,
Bk. mallei(glanders),B. pseudomallei(melioidosis),
Hanta virus, Nipa virus, and other emerging infections.
Disease unusual for an age group
Unusual strains, variants or antimicrobial
resistance patterns
We have become so accustomed to seeing multidrug
resistance, that this may not arouse suspicion.
Similar or genetically identical organisms
isolated from different sources at different
times, especially those that do not appear to
have an epidemiologic link
This will not be initially apparent and will require a high
enough index of suspicion for the clinician to order the
appropriate genetic testing.Markedly different attack rates between persons
indoors and outdoors.
This will not be initially apparent to the clinician.Disease outbreaks in places not connected by
geography or epidemiology.
Disease outbreak that is both human and
zoonotic; an increase is noted in dying or dead
animals
Unless there is a history of the patients’ pets or livestock
becoming ill, this will not be apparent to the clinician,
especially in an inner city hospital.
Intelligence about or threats from terrorists.
Source: From Refs. 1, 2, 5, and 12.
438 Cleri et al.