Epidemiologic Features of a Possible Bioterrorism Event

1. A rapidly increasing disease incidence in a normally healthy population.
   Example: Three days ago 5 people were seen with nausea, vomiting, fever and diarrhea. Two days ago 12 people were seen, yesterday 20 were seen and now 10 have been seen just this morning.
   

2. An epidemic curve that rises and falls during a short period of time.
   Example: Twenty cases of diarrheal illness seen in the emergency department within 4 hours. No cases seen in the 2 days before or after.
   

3. An unusual increase in the number of people seeking care, especially with fever, respiratory, or gastrointestinal complaints.
   Example: No cases of respiratory illness in the last 2 weeks. The first 5 patients of the day have pneumonia and 10 more have called and are coming in with the same symptoms.
   

4. An endemic disease (disease always found in a population) rapidly emerging at an uncharacteristic time or in an unusual pattern.
   Example: Ten patients diagnosed with influenza in July.
   

5. Higher attack rates among people who had been indoors, especially in areas with filtered air or closed ventilation systems, compared with people who had been outdoors.
   Example: Twelve people seen today with respiratory symptoms. All had been at a daylong meeting in a local motel conference room 4 days ago. No other patients with the same symptoms.
   

6. Clusters of patients arriving from a single location.
   Example: Seven people admitted today from a local nursing home with the same respiratory symptoms.
   

7. Large numbers of rapidly fatal cases.
   Example: Two people admitted last night with abdominal pain, fever and bloody diarrhea. Developed HUS and died within 18 hours.
   

8. Any patient presenting with a disease that is relatively uncommon and has bioterrorism potential.
   Example: The x-ray department calls and says, "This is the weirdest x-ray we have seen. I think this looks like the x-ray of an anthrax patient we saw at a seminar."