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Humans become infected as they come into contact with infected
animals or their products.    The ultimate reservoir of Bacillus
anthracis  is  the soil,  however,  it is  clear that  simple  soil
contamination with anthrax spores does not necessaryily give rise
to cases and that certain meteorological conditions are necessary.
A vegetative phase is necessary whereby anthrax spores multiply to
a density sufficient to cause disease in animals that graze in the
area.   Inhalation anthrax occurs naturally when aerosols of anthrax
spores are generated during the early processing of imported goat
hair.   Since the disease follows inhalation of anthrax spores, it
is  never  seen  as a  result of   contact with  recently  infected
animals.
  VIRULENCE  of  Bacillus  anthracis  is dependent   upon  plasmid
mediated production of   a three-component exotoxin and an anti-
phagocytic capsule.   The toxic proteins, collectively referred to
as "anthrax toxin," have been purified and cloned and consist of
a protective   antigen  (PA), an edema  factor  (EF), and a  lethal
factor   (LF).  Inhaled anthrax spores that are greater than 5 um
pose no problem, as they are physically cleared from the lung by
the mucociliary escalator system.   Smaller particles are deposited
in  alveoli  or  alveolar ducts  where  they  are  phagocytized  by
alveolar macrophages and carried to mediastinal lymph nodes.      A
hemorrhagic  mediastinitis   results, followed   by bacteremia  and
intravascular multiplication of organisms.  Meningitis often occurs
as a part of the overwhelming septicemia.     INHALATION anthrax is
very difficult to diagnose early.     The disease is biphasic,  and
initial  symptoms mimic a severe viral respiratory    illness  like
influenza.   This lasts for 2 to 3 days and is followed by a second
more  acute  phase characterized   by severe  hypoxia and  dyspnea.
CHEST X-RAY films consistently show widening of the mediastinum.
Patients   soon  become hypotensive,  and  about  one-half  develop
meningeal signs.
  Bacillus anthracis cells are large,    gram-positive bacilli and
individual cells have square or concave ends.    Ovoid, subterminal
endospores that do not cause any significant swelling of the cells
may be observed.   The spores appear as unstained areas within the
bacterial cells in GRAM'S STAINed preparation.   The organism grows
well on ordinary blood agar within 18 to 24 hours at 35 degrees
Centigrade.    The colonies are typically flat and irregular,  4 mm
to 5 mm in diameter and is not hemolytic on sheep blood agar.
  Few good data exist on the TREATMENT of inhalation anthrax but
recent animal studies have prompted the Armed Forces Epidemiology
Board to recommend treatment of suspicious clinical symptoms with
a loading dose of ciprofloxacin    (1000 mgm)   followed by 750 mgm
twice a day, intravenous doxycycline (200 mgm loading dose followed
by 100 mgm two times daily), or other appropriate antibiotics such
as high dose penicillin.     If the patient has had pre-exposure
vaccination, an additional booster is recommended during therapy.
If  no  pre-exposure  vaccination has occured,   initiation  of the
vaccination series while on antibiotics is recommended.
  The    human  anthrax  VACCINE   consists   of  alum-precipitated
supernatant material from fermentor cultures of toxigenic,     non-
encapsulated strains of Bacillus anthracis.   The vaccine series is
a two   shot series two weeks apart with a booster recommended.


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