Table 2.

Primary Care Probabilistic Differential Diagnosis for Inhalation Anthrax

Diagnoses (ICD-9 Code)	Responses No. (%)	Cumulative Percentage
1. Pneumonia (480-486)	237 (42.4)	42.4
2. Influenza (487)	56 (10.0)	52.4
3. Viral syndrome (079.99)	48 (8.6)	61.0
4. Septicemia (038)	43 (7.7)	68.7
5. Bronchitis (466)	41 (7.3)	76.0
6. CNS infection (047-049, 320-323)	35 (6.3)	82.3
7. Gastroenteritis (008-009)	21 (3.8)	86.1
8. Upper respiratory tract infection (460, 465)	17 (3.0)	89.1
9. Nonspecific febrile illness (780.9)	10 (1.8)	90.9
10. Chronic obstructive pulmonary disease (496)	8 (1.4)	92.3
11. Congestive heart failure (428.0)	7 (1.3)	93.6
12. Pulmonary embolism (415.1)	5 (0.9)	94.5
13. Tuberculosis (011.0-011.9)	4 (0.7)	95.2
14. Sinusitis (461.0-461.9)	2 (0.4)	95.6
15. Dehydration (276.0-276.5)	2 (0.4)	95.9
16. Syncopal episode (780.2)	2 (0.4)	96.3
17. Hantavirus pulmonary syndrome (480.8)	2 (0.4)	96.6
18. Adult respiratory distress syndrome (518.5)	2 (0.4)	97.0
19. Dementia (294.1)	1 (0.2)	97.2
20. Acute multiple sclerosis (340)	1 (0.2)	97.4
21. Pyelonephritis (590.1)	1 (0.2)	97.6
22. Diabetic ketoacidosis (250.1)	1 (0.2)	97.7
23. Angina (413.0-413.9)	1 (0.2)	97.9
24. Coxsackie virus infection (074.0-074.8)	1 (0.2)	98.1
25. Pleurisy (511.0-511.9)	1 (0.2)	98.3
26. Lyme disease (088.81)	1 (0.2)	98.5
27. Leukocytosis (288.8)	1 (0.2)	98.7
28. Interstitial pneumonitis (515)	1 (0.2)	98.8
29. Mononucleosis (075)	1 (0.2)	99.0
30. Pericarditis (420.0-420.99)	1 (0.2)	99.2
31. Empyema (510)	1 (0.2)	99.4
32. Aortic dissection (441.0-441.9)	1 (0.2)	99.6
33. Plague (Yersinia pestis) (020.0-020.9)	1 (0.2)	99.7
34. Tularemia (021.0-021.8)	1 (0.2)	99.9
35. Intestinal perforation (569.83)	1 (0.2)	100.0
Total	559 (100)

Note: Of the nonanthrax diagnoses, 559 were from inhalational anthrax cases, 52 from Legionella cases, and 105 from the influenza cases.

ICD-9 = International Classification of Diseases, 9th Revision; CNS = central nervous system.