Medical personnel should be able to distinguish:

Select IDs and toxins are described in Appendix H and characterized by syndrome. These tables are examples and not intended to be totally comprehensive. Appendix A contains syndromic algorithms with potentially diagnostic clinical clues to illustrate how to narrow the differential diagnosis for some of these agents. Clinicians should be cautious at excluding one type of agent too early as there can be overlaps in syndromes during the early stages of illness.

Many biothreat induced illnesses will present as an undifferentiated febrile illness that progresses to another syndrome (cutaneous, hemorrhagic, or neurological, etc.). The progression sequence and timing can suggest different causative agents. It is important that all levels of medical personnel maintain a high index of suspicion for biothreats: initially recognizing that a biothreat may be present is necessary for all further steps in identifying it. Depending on geographic location, season, and local environment, endemic cases of bio-agents may be present commonly (many cases per year), uncommonly (few cases present every year), or rarely (cases have been identified before but do not reliably occur every year). Patients presenting with a potentially endemic disease, but at an atypical location or season, or in larger numbers than expected compared to prior years, should trigger suspicion of a potential bio-agent attack. In addition, if there is suspicion of a bioincident, action should not wait for syndromic characterization. Early fever may be the only presenting feature, so a high degree of suspicion, based with intel may be needed.

Combining the syndromic characterization of an illness (for example, an unusual cluster of unexplained fevers), with the epidemiological patterns and risk factors may provide the best clinical picture of the potential causative agent(s) and can guide further treatment and testing. It is important to note that these characteristics are an approximate guide, and the presence or absence of a specific characteristic should not be taken as definitive proof for, or against, inclusion of a biothreat in the differential diagnosis. Particularly in biological warfare attempts, agents may appear with uncharacteristic or novel epidemiological patterns or syndromic characters due to unexpected routes of exposure, or intentional modifications to the biothreats’ genome. Many potential bio-warfare agents are also endemic infectious diseases. (See Appendix C.) However clinical context is important, as an atypically large number of cases of an endemic disease or cases not associated with typical risk factors (e.g., wild rodent exposure for plague or tularemia) suggest an intentional outbreak. Smallpox is a notable exception. It was eradicated from nature in 1980, so any identified cases indicate a bio-warfare use.