Biomedical Engineering Reference
In-Depth Information
children) for seven days may also be used. Alter-
natives include ofloxacin, levofloxacin, chloram-
phenicol, and TMP-SMX.
Hospital infection control measures are an
important component of management of plague
patients. The incision and drainage of buboes
may pose a hazard to medical personnel, although
buboes may be aspirated for diagnostic purposes.
Droplet precautions should be strictly enforced
for at least 72 hours after the initiation of effec-
tive therapy. Surface decontamination can be
performed with 0.5% sodium hypochlorite solu-
tion (1 part household bleach added to nine parts
water) [3,5,8,10,11,13].
4.4.3 Diagnosis
As with other BT threat diseases, a preliminary
diagnosis should be based upon clinical findings.
Supporting evidence may be gained by demon-
strating classic poxviruses on material from lesions.
Culture should only be attempted in a qualified
BSL-4 laboratory at the CDC or USAMRIID [5,7].
4.4.4 Differential Diagnosis
The differential diagnosis for smallpox includes
chickenpox and monkeypox, allergic contact
dermatitis, erythema multiforme with bullae, orf,
disseminated herpes zoster, impetigo, coxsack-
ievirus, secondary syphilis, atypical measles, and
adverse drug eruptions. Smallpox cases often
present with a rash that is centrifugal in distri-
bution, or most dense on the face and extrem-
ities. The lesions appear at a 1-2 day period,
evolve at the same rate, and are generally at
the same stage of development (i.e., vesicles,
pustules, or scabs). In varicella (chicken pox),
new lesions appear in groups every few days,
and lesions at different stages of maturation are
found in adjacent dermal areas. Varicella lesions
are distributed centripedally, with a greater concen-
tration on the trunk than the extremities; and
are superficial, not occurring on the palms and
soles, unlike variola. Monkeypox is more diffi-
cult to distinguish from smallpox, although gener-
alized lymphadenopathy is a common feature of
monkeypox, the lesions are not as numerous, nor
is the disease as severe. Person-to-person spread
of monkeypox is rare [5,7].
4.4 Disease: Smallpox
4.4.1 Causative Agent
Variola (smallpox) virus could be used as a biolog-
ical weapon in aerosol form or inoculated onto
fomites. The virus is usually spread by the respira-
tory route, is environmentally stable, and may also
be spread through direct contact [5,7].
4.4.2 Clinical Description
The incubation period for smallpox is between
7-17 days. Smallpox is an illness with acute
onset of fever of 101
F or more followed by a
rash characterized by vesicles or firm pustules.
Lesions are classically synchronous in nature. The
prodrome lasts 2-4 days and includes malaise,
fever, rigors, headache, and backache. This is
followed by a typical skin eruption (from macules
to papules to vesicles to pustules, and then scabs
over 7-14 days). Fever may reappear 7 days after
the onset of the rash. Smallpox has had a 20-50%
mortality rate. Flat-type smallpox, characterized by
slow evolution of flat, soft, focal skin lesions, and
severe systemic toxicity has been noted in 2-5% of
patients. Mortality for flat-type smallpox was 66%
in vaccinated patients and 95% in unvaccinated.
Hemorrhagic-type smallpox is characterized by the
appearance of extensive petechiae and mucosal
hemorrhage, is seen in about 3% of patients, and
usually results in death [5,7].
4.4.5 Medical Management
Antivirals for use against smallpox (e.g., cido-
fovir) are under investigation. Supportive treatment
should be given [5,7].
4.4.6 Vaccine/Prophylaxis
Wyeth Calf Lymph Vaccine and DOD cell-culture-
derived Vaccinia must be given by scarifica-
tion. Smallpox vaccination should be given to
all contacts and healthcare workers caring for
suspect smallpox patients,
irrespective of prior
