EPIDEMIOLOGIC CLUES

1. Large numbers of ill persons with a similar disease or syndrome
2. Large number of cases of unexplained diseases or deaths
3. Unusual illness in a population (e.g., renal disease in a large population may suggest exposure to a toxic agent such as mercury)
4. Higher morbidity and mortality in association with a common disease or syndrome or failure of such patient to respond to usual therapy
5. Single case of disease caused by an uncommon agent (smallpox, pulmonary anthrax)
6. Multiple disease entities in the same patients, indicationg that mixed agents have been used in the attack
7. Apparent aerosol route of infection
8. Illness limited to fairly localized or circumscribed geographical areas.
9. Low attack rates in personnel who work on areas with filtered air supplies or closed ventilation systems
10. Sentinel dead animals of multiple species
11. Simultaneous cluster of similar illness in noncontiguous areas
12. Ill persons who seek treatment at about the same time (point source with compressed epidemic curve)
13. No illness in persons who are not exposed to common ventilation systems (have separate closed ventilation systems) when illness is seen in persons in close proximity who have a common ventilation system
14. Several unusual or unexplained diseases coexisting in the same patient without any other explanation
15. Atypical disease transmission through aerosols, food, or water, which suggest deliberate sabotage
16. Stable endemic disease with an unexplained increase in incidence (i.e. tularemia, plague)