The US capitol bioterrorism anthrax exposures: clinical epidemiological and immunological characteristics.
BACKGROUND
Bioterrorism-related anthrax exposures occurred at the US Capitol in 2001. Exposed individuals received antibiotics and anthrax vaccine adsorbed immunization.


METHODS
A prospective longitudinal study of 124 subjects--stratified on the basis of spore exposure, nasopharyngeal culture results, and immunization status from inside and outside an epidemiologically defined exposure zone--was performed to describe clinical outcome and immune responses after Bacillus anthracis exposure. Antibody and cell-mediated immune (CMI) responses to protective antigen (PA) and lethal factor were assayed by enzyme-linked immunosorbent assay and fluorescence-activated cell sorting.


RESULTS
Antibody and CMI dose-exposure responses, albeit generally of low magnitude, were seen for unimmunized subjects from inside, within the perimeter, and outside the exposure zone and in nonexposed control subjects. Anti-PA antibody and CMI responses were detected in 94% and 86% of immunized subjects. No associations were seen between symptoms and exposure levels or immune responses.


CONCLUSIONS
Anthrax spores primed cellular and possibly antibody immune responses in a dose-dependent manner and may have enhanced vaccine boost and recall responses. Immune responses were detected inside the perimeter and outside the exposure zone, which implies more-extensive spore exposure than was predicted. Despite postexposure prophylaxis with antibiotics, inhalation of B. anthracis spores resulted in stimulation of the immune system and possibly subclinical infection, and the greater the exposure, the more complete the immune response. The significance of low-level exposure should not be underestimated.
Doolan
Denise L
DL
Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA. dooland@nmrc.navy.mil
Freilich
Daniel A
DA
Brice
Gary T
GT
Burgess
Timothy H
TH
Berzins
Mara P
MP
Bull
Robert L
RL
Graber
Norma L
NL
Dabbs
Jason L
JL
Shatney
Lori L
LL
Blazes
David L
DL
Bebris
Lolita M
LM
Malone
Maria F
MF
Eisold
John F
JF
Mateczun
Alfred J
AJ
Martin
Gregory J
GJ
D000881:Anthrax / Q000453:epidemiology* / Q000276:immunology* / Q000503:physiopathology / Q000517:prevention & control; D022122:Anthrax Vaccines / Q000008:administration & dosage* / Q000276:immunology; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000276:immunology; D001408:Bacillus anthracis / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D001427:Bacterial Toxins / Q000276:immunology; D023482:Bioterrorism; D004219:District of Columbia / Q000453:epidemiology; D006801:Humans; D007115:Immunization Schedule; D019570:Inhalation Exposure; D008214:Lymphocytes / Q000276:immunology; D009000:Monocytes / Q000276:immunology; D013171:Spores, Bacterial / Q000276:immunology; D016896:Treatment Outcome
D022122:Anthrax Vaccines; D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin