Download Smallpox Charlotte McKinley Jessica Midence Izabella Messina

Smallpox
Charlotte McKinley
Jessica Midence
Izabella Messina
Smallpox




Smallpox is a serious, contagious and sometimes
fatal disease.
There is no specific treatment for smallpox, and the
only prevention is vaccination.
The name smallpox is derived from the latin word
“spotted” and refers to the raised bumps that appear
on the face and body of an infected person.
Smallpox is in the Orthopoxvirus genus of viruses.
Origin of Smallpox



The name Variola was first used in the 6th century.
Derived from the Latin word varius (spotted) or
varus (pimple).
Anglo-Saxons in the 10th century used the word poc
or pocca (bag or pouch) to describe an
exanthemous disease, possibly smallpox.
In the 15th century, the English used the prefix small
to distinguish variola the smallpox from syphilis, the
great pox.
First Case of Smallpox



There is no animal
reservoir, and no human
carriers.
First certain evidence
comes from the mummified
remains of Ramses. (1157
B.C.)
Written descriptions did not
appear until the 10th
century in Southwestern
Asia.
Smallpox Travel



Smallpox was likely carried from Egyptian traders to
India during the millennium B.C. where it became
established as an endemic infection.
Epidemics of the disease can be found in the bible,
and in ancient Greek and Roman literature.
From Asia and Africa smallpox spread with
increasing frequency into less populous areas, and
then into Europe.
Smallpox in the Ancient World





Peloponnesian Wars (430 B.C.)
Thucydides recorded smallpox symptoms.
A person aboard a ship from North Africa came to
Athens infected with smallpox.
Described as violent heats, unnatural, putrid odors,
stomach distress, and the body covered with small
pustules and ulcers.
Also noted that those who survived became
immune.
Smallpox in the New World



In the early 16th century smallpox began to
imported into the western hemisphere.
The Spanish inadvertently owe success in
conquering the Aztec and Incas in Mexico to
smallpox.
Smallpox arrived in North America via
Canada, and Mexico.
Smallpox as Biological Warfare


Lord Jeffrey Amherst, Commanding General
of British Forces in North America during the
French and Indian War. (1754-1763)
Used blankets (smallpox blankets) coated
with smallpox dust as germ warfare to wipe
out the Native American population.
History of Variolation and Vaccine



Known that survivors became immune to the
disease.
As a result, physicians intentionally infected healthy
persons with smallpox organisms.
Variolation is the act of taking samples (pus from
pustules or ground scabs) from patients whose
disease had been benign, and introducing it into
others through the nose or skin.
Survival Rates with Variolation



Two to Three percent of variolated persons died of
smallpox, became the source of a new epidemic, or
developed other illnesses from the lymph of the
donor such as tuberculosis or syphilis.
The case fatality rates were still ten times lower in
those that were variolated compared to those with
naturally occurring smallpox.
Side effects of variolation were the appearance of
smallpox itself, but it would disappear after a week
or so.
Variolation in the New World





Reached the New World in 1721.
Used to stop the epidemic in Boston.
In 1766 American Soldiers under George
Washington were unable to take Quebec from the
English because of smallpox.
Smallpox was apparently one of the main causes of
the preservation of Canada in the British Empire.
In 1777 Washington had all of his soldiers variolated
beginning with new military operations.
Cows, Milkmaids, and the Pox



In rural areas of Europe it was known the milkmaids
became immune to smallpox after developing
smallpox
1774, farmer Benjamin Jesty was the first to
vaccinate his wife and kids with material taken from
the utters of cows.
1791, school teacher Peter Plett vaccinated his
students with material from the utters of cows.
Edward Jenner
Edward Jenner





Studied to become a physician in England.
In May of 1776 dairymaid Sarah Nelmes consulted
Jenner about a rash on her hand.
He took this opportunity to test the protective
properties of cowpox against smallpox.
Determined that cowpox can be passed from person
to person as well as from cow to person.
The next step was to see if the cowpox would
protect the patient from smallpox.
Edward Jenner





Jenner published the data collected in 1798.
However, Jenner’s technique did not catch on as
anticipated.
After more and more people were becoming
immune to smallpox vis a vis cowpox it became
accepted as the way of the future.
In 1840 variolation was forbidden by an Act of
Parliament.
In England vaccination with cowpox became
compulsory in 1853.
Edward Jenner



Jenner spent his time supplying cowpox material to
others around the world.
In recognition of his work the British government
awarded Jenner ten thousand pounds in 1802, and
twenty thousand pounds in 1807.
Jenner was honored for his technique, and vaccine
became the universally used term to indicate
introducing material under the skin to produce a
protection against disease.
Eradication






In 1801 Jenner said, “The annihilation of the
smallpox, the most dreadful scourge of the human
species, must be the final result of this practice.”
Compulsory vaccinations began in the following
years:
1807 in Bavaria
1810 in Denmark
1835 in Prussia
1853 in Britain
Eradication



Even after vaccination outbreaks still continued
because the virus was imported by travelers where
there were still endemics.
Not until after WWI did most of Europe become
smallpox free, and not until after WWII was
transmission stopped throughout Europe and North
America.
In less developed countries smallpox continued
largely unabated until the middle of the 20th century.
Eradication



1940s: large scale preparations of a stable freeze
dried vaccine was perfected by Collier.
1950: Pan American Sanitary Organization decided
to undertake a hemisphere wide eradication
program.
1958: Union of Soviet Socialist Republics proposed
to the WHO that a global smallpox eradication
program be undertaken.
Eradication



The campaign was based on a two fold
strategy.
1) Mass vaccination campaigns in each
country using a vaccine of ensured potency
and stability that would reach at least 80% of
the population.
2)Development of a system to detect and
contain cases and outbreaks.
Eradication


26 October 1977 the last naturally occurring
case of smallpox was recorded in Merka
Somalia.
In 1978 two cases were reported. These
were both from people working in labs with
smallpox in England.
Eradication



1980: WHO formally declared that smallpox
was dead.
The eradication of smallpox was one of the
most important branches of modern
medicine.
Jenner has been acknowledged as the father
of immunology,
TAXONOMY
FAMILY: POXVIRIDAE
1. SUBFAMILY: CHORDOPOXVIRINAE (infect vertebrates)
GENERA: ORTHOPOXVIRUS (variola, vaccinia, cowpox, monkeypox)
AVIPOXVIRUS (fowlpox)
CAPRIPOXVIRUS (sheep-pox)
LEPORIPOXVIRUS (myxoma)
PARAPOXVIRUS (milker’s nodule)
SULPOXVIRUS (swinepox)
2. SUBFAMILY: ENTOMOPOXVIRINAE (infect arthropods)
Species of the Genus Orthopoxvirus
Species
Animals Infected
Host Range
Geographic Range
Variola
Human
Narrow
Formerly worldwide
Vaccinia
Human,a cow, pig, buffalo,
rabbit, etc.
Broad
Worldwideb
Cowpox
Rodent,a cow, human, cat, etc.
Broad
Europe
Monkeypox
Squirrel,a monkey, ape, human
Broad
Western and central Africa
Ectromelia
Mouse, mole
Narrow
Europe
Camelpox
Camel
Narrow
Africa and Asia
Taterapox
Gerbil
Narrow
Western Africa
Volepox
Vole
?
United States
Raccoonpox
Raccoon
?
United States
Skunkpox
Skunk
?
United States
Uasin Gishu
Horse
Medium
Eastern Africa
aPrimary
host.
to vaccination; no known natural host.
bSecondary
http://books.nap.edu/html/variola_virus/ch2.html#TopOfPage
CHARACTERISTICS SHARED BY
SPECIES OF ORTHOPOXVIRUS :
- The largest and most complex viruses
- Virons particles can be seen with a light microscope
- They contain a linear genome of a single
double-stranded DNA
- They replicate in the cytoplasm of the host cell,
therefore they must provide their own mRNA and
DNA synthetic machinery
(including DNA-dependent RNA polymerase)
- Inclucison bodies: type B and type A
- Virions have a brick-like shape and are present in
2 forms, both are infectious:
1. EEV (Extracellular Enveloped Virus)
2. IMV (Intracellular Mature Virus)
- Serological cross-reactivity
- Produce a hemagglutininin antigen (HA)
- Vaccinia is the most intensively studied member of
the poxvirus family
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
MORPHOLOGY OF THE VIRION
- have an brick-like shape; dimensions 400x200nm
- four major elements:
1. core ( 9 nm thick membrane, biconcave disk,
a tightly compressed nucleoprotein)
2. lateral bodies ( unknown function)
3. outer membrane ( a protein shell 12nm thick,
the surface consists of irregularly arranged tubules)
4. envelope ( an inconstant element,
proteins are glycosylated and acylated)
- Virons are present in two infectious forms:
1. EEV (Extracellular Enveloped Virus)- released from
cells spontaneously, by exocytoses are enclosed within
a lipoprotein envelope, which contains the haemagglutinin
and other specific polypeptides
- CEV (Cell Associated Enveloped Virus)
2. IMV (Intracellular Mature Virus) – released by
cellular disruption, lacks envelope, “naked virus”
Vaccinia Virus – Electron micrographs
A. Non- enveloped virion (surface of outer membrane with tubular elements)
C. Thin section of non-enveloped virion (biconcave core)
B. Enveloped virion, found in extracellular medium
D. Viral core, released after treatment of virions with Nonidet
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
VIRAL REPLICATION – CELL CYCLE
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
VIRAL REPLICATION – CELL CYCLE
http://www.rkm.com.au/VIRUS/SMALLPOX/smallpox-life-cycle.html
CELLULAR CHANGES
“Viral factory” visualized in stained cells as
the B-type inclusion body, is first seen at 2.5h
cupules first appear at 4 hours and some are
completed as immature particles 6-8hours.
From 8 hours onwards mature particles appear.
“Toxic”changes may occur in the inf.cells, which in
monolayer cultures become rounded and retract
from each other.
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
Cytoplasmic inclusion bodies in infected cells
B-type (Guarnieri bodies)- sites of viral replication
produced by all orhopoxviruses
A-type – strongly eosinophilic, found in cells infected with: cowpox,ectromelia and
raccoonpox virus; appear late in the infection and are not associated with
viral replication (may contain mature virions)
Fenner,F. et al. Smallpox and Its Eradiction. Genevea, Switzerland:WHO. 1998:1460
STRUCTURE OF THE VIRAL GENOME
- Schemat of vaccinia virus DNA
- Contains a single linear molecule of a double stranded DNA
About 200 kbp long; guanine+cytosine content 36%
- when denatured the two sister strands form a large single-stranded circular molecule,
being attached at each end of the genome by covalent links
- for the most part, the DNA sequences in the central part of the genome are unique,
but the terminal fragments (inverted terminal repeats) cross-hybridize with each other
and with the termini of other species of orthopoxvirus
- The ITR’s include: an A+T-rich, incompletely base-paired, hairpin loop that connects the
two DNA strands; set of short tandemly repeated sequences. The ITR’s are variable in
length owing to deletions, repetitions, and transpositions
- Inverted repeats in vaccinia are 10 kbp long
in variola are 725 bp
- Variola vs. Vaccinia: genomes are highly conserved with >95% nucleotide identity,
however towards the termini the sequences diverge
Poxviruses that have been inactivated that don’t damage their DNA
can be reactivated
VIRAL PROTEINS
-Encodes about 200 proteins
-The central part of the genome encodes for structural and functional proteins;
Virulence genes are found near the inverted repeats,
-numerous virus-encoded enzymes,are packaged within the virus core,
including:
* multisubunit DNA-dependent RNA polymerase
* RNA polymerase associated protein of 94kd (RAP94)
* a transcription factor (VETF)
* capping and methylating enzymes
* poly(A) polymerase
These components are used to synthesize translatable mRNA
-Importatnt proteins for replication:
* topoisomerase
* thymidine kinase – allows the incorporation of Thymidine into DNA
* thymidylate kinase – catalyzes the reversible phosphorylotransfer between ATP and TMP
* ribonuceoside reductase – converts ribonucleoside diphosphates ( NDP’s ) into deoxyNDP’s
* dUTPase – minimize the misincorporation of Uracil into DNA
* Uracil-DNA gylclosylase – removes the RNA base (Uracil) from DNA
* DNA ligase
non enzymatic -VIRAL PROTEINS
1. Membrane proteins:
A33R, A34R, A36R :*N-glycosylated, phosphorylated
* fromation of actin tail and microvilli, which facilitate
viral dissemination
A36R : required for kinesin recruitment and is involved in
microtubule-based motility of IEV’s
A56R: Hemagglutinin, N- and O- glycosylated , promote cell fusion and
cell to cell viral spread
A27L: required for the formation of IEV, fusion protein,
microtubule –dependent movment,
normal sized plaques , has additional role in the viral assembly
A28L: fusion protein; A28 deficient virions with normal amounts of A27 and
A17 (binding partner) are unable to induce cell fusion
2. Core proteins:
F17R, L4R, A3L, A10L : account for ~70% of the viral core by weight,
bind DNA
VIRAL IMMUNOMODULATORY STRATEGIES
1. Poxviruses encode multiple classes of immunomodulatory proteins to inhibit
diverse processes as:
* apoptosis
* the production of interferon
* the production of chemokines and inflammatory cytokines
* the activity of complement, NK, CTL’s, antibodies
2. The inhibitory proteins, produced by virus, fall into three main classes:
- Virokines * resemble host cytokines
* secreted from infected cells to block hosts receptors
* vIL-10, vIL-18
- Viroreceptors * mimic host cellular receptors
* altered cellular receptors that have lost their transmembrane
sequnces and consequently are secreted from infected cells
to sequester ligands
* vINF-Rs, vTNFRs
- Intracellular proteins * target host signal transduction pathways
* inhibit inner antiviral pathways:
apoptosis – vFLIP’s, serpins
proinflammatory cascades - TNF
VIRAL IMMUNOMODULATORY PROTEINS
j
Johnston,J.B.et al.Poxvirus Immunomodulatory Strategis:Current Perspectives.
Journal of Virology (2003), 77: p.6093-6100
VIRAL IMMUNOMODULATORY PROTEINS
Complement Regulatory Proteins
- VCP – Vaccinia virus Complement control Protein, consists of short consensus
repeats found in hosts’ complement regulatory proteins.
Inhibits the classic and alternative pathways of complement through
binding and inactivating both C4b and C3b
-SPICE- the smallpox inhibitor of complement enzymes
- molecularly engineered homologue of VCP (Rosengrad et al;.Univ. of Penn.)
Demostrated: the functional advantage of variola complement regulatory protein
Over the vaccinia homologue
- More human complement specific than VCP
-100-fold more potent at inactivating C4b&C3b;
-SPICE serves to inhibit the formation of the C3/C5 convertases necessary for
Complement-mediated viral clearance
SPICE- provides the first evidence that variola proteins are particulary adept at
overcoming human immunity, and the decreased function of VCP suggests one
reason why the vaccinia virus vaccine was associated with relatively low mortality.
Disabling SPICE may be useful therapeuticaly
Smallpox
Clinical Presentations, Transmission,
Treatment, Vaccination
Transmission of Smallpox







Humans are the only natural host of smallpox and it is not known to
be transmitted by insects or animals (no animal reservoir)
Transmission generally occurs from direct and fairly prolonged faceto-face contact (in order for infected spit particles to pass from one
person to another)
Infected aerosols and air droplets spread in face-to-face contact with
an infected person after fever has begun, esp. if symptoms include
coughing
Smallpox can also be spread through direct contact with infected
bodily fluids or contaminated objects (ie. Bedding and clothing)
In rare instances, smallpox can spread through the air of an
enclosed area
Variola major renders infected people bedridden so spreading to
the community is reduced
In variola minor, however, the symptoms are so mild that patients
remain ambulatory during the infection phase and can spread the
virus more widely
Pathogenesis of Smallpox





The portal of entry for smallpox is the respiratory tract or inoculation
on the skin
Excretions from the mouth and nose, rather than scabs, are the most
important source of infectious virus
Studies have shown that primary infection in the nose or mouth do
not produce a “primary lesion” that ulcerates and releases virions
onto the surface
Four models have been studied to learn about the spread of the
infection through the body: mousepox in mice, rabbitpox in rabbits,
and monkeypox and smallpox in monkeys and apes
During incubation the virus proceeds through infection, replication,
and liberation (usually accompanied by cell necrosis) first at the site
of inoculation and then to the regional lymph nodes, then deeper
lymph nodes and possibly into the bloodstream
Pathogenesis of Smallpox





When tests were performed on humans to determine the
pathogenesis, the virus was only rarely collected from the serum
of infected persons, even though viraemia had definitely occurred
Therefore it was determined that viraemia in ordinary smallpox
was restricted to the pre-eruptive and early eruptive stages of the
disease
In hemorrhagic smallpox, however, virus was readily found in the
blood and titers were high; thus hemorrhagic smallpox can be
associated with overwhelming infection and the continued
release of virus into the bloodstream
The primary event for production of lesions of the rash in
orthopoxvirus infections is localization (in the small blood vessels
of the dermis) of virus particles that circulate in the bloodstream
Vasodilation leads to greater density of lesions
Pathogenesis of Smallpox







After introduction of smallpox into the oropharyngeal cavities it spreads
to the regional lymph nodes
Asymptomatic viremia occurs on the 3rd or 4th day after infection, with
further dissemination of the virus to spleen, bone marrow, and other
lymph nodes.
The virus localizes in small blood vessels of the dermis and
oropharyngeal mucosa, leading to initial onset of the enanthem and
exanthem, at which point (about day 14) the patient becomes infectious
The spleen, lymph nodes, kidneys, liver, bone marrow, and other
viscera also may contain large amounts of virus
Secondary viremia occurs by the 8th to 12th day after initial infection;
this is followed by onset of fever and toxemia.
Smallpox is disseminated through the body in the lymph and
bloodstream as cell-associated particles
Enveloped forms of the virus are more important than non-enveloped in
the dissemination of the virions over a distance
Pathogenesis of Smallpox

The development and evolution of skin lesions is an extremely
valuable clue to the diagnosis and involves the following steps:
 Dilatation of the capillaries in the papillary layer of the dermis occurs
initially, followed by swelling of the endothelial cells in the vessel
walls; perivascular cuffing with lymphocytes, plasma cells, and
macrophages can be seen.
 Lesions then develop in the epidermis, where the cells become
swollen and vacuolated; characteristic B-type inclusion bodies can be
found in the cytoplasm.
 The cells increase in size and the cell membranes rupture, leading to
vesicular lesions.
 Pustulation results from the migration of polymorphonuclear cells into
the vesicle.
 The contents of the pustule gradually become desiccated, leading to
crusting or scabbing of the lesions.
 Re-epithilialization and scarring occur as the lesions heal.
Effects on Other Organs




A striking feature of smallpox reports is that there is
an absence of specific lesions anywhere except in
the skin and mucous membranes
The endothelial cells lining the sinusoids of liver
were often swollen and occasionally proliferating or
necrotic (in more severe cases)
Reticulum cell hyperplasia occurred in bone marrow
and spleen
Spleen was usually engorged with very numerous
large lymphoid cells
Pathogenesis of Smallpox


When studies were done on rabbits with
rabbitpox to determine the cause of death the
rabbits had extreme hypertension, leading to
a shock-like syndrome, decreased urinary
output and a rise in blood-urea and plasma
potassium levels
Death seemed to be caused by lethal
concentrations of potassium ion, which was
possibly from the hypertension
Clinical Presentations







Smallpox is also called Variola
4 orthopoxviruses are known to infect humans: variola,
vaccinia, cowpox, and monkeypox
Variola virus is strictly a human virus, although primates
and other animals can be infected under lab conditions
Infection begins when the virus comes into contact with
oropharyngeal (mouth and throat) or respiratory mucosa;
virus multiplication then occurs in regional lymph nodes
There are 2 clinical forms of Smallpox: Variola Major and
Variola Minor
Variola major is severe and the most common form with
more extensive rash and higher fever with a death rate
of about 30%
Variola minor has less common presentation and much
less severe with death rate of 1% or less

Variola Major has 4 clinical presentations
based on the nature and evolution of the
lesions; those 4 types are:



Ordinary: most frequent (more than 90% of cases
in both vaccinated and unvaccinated persons);
corresponds to classical description of smallpox
Modified: milder and may occur in previously
vaccinated people; rarely fatal
Flat and Hemorrhagic: very severe but uncommon
Stages of Smallpox

Incubation Period



Lasts on average 12-14 days but can range from 7-17 days
Person is not contagious and exhibits no symptoms
Prodrome Phase
 This is when initial symptoms develop and is also called the preeruptive stage
 Begins abruptly with fever, malaise, headache, head and body
aches, prostration, and often nausea and vomiting
 Body Temperature rises to at least 101F and is often higher
 Note that this severe febrile prodrome right before the onset of
the rash is characteristic of smallpox and can be used to
differentiate it from other rash illnesses
 This phase lasts 2-4 days and is sometimes contagious
Stages of Smallpox: Rash Phase










When the first visible lesions appear the fever may start to go down
This is the most contagious period (the time when the saliva has the most virus
in it)
Lasts 4 days
Rash emerges as small red spots on tongue and in mouth (about 24 hours
before the appearance of rash on the skin)
Lesions in the mouth and pharynx enlarge and ulcerate quickly, releasing large
amount of virus into the saliva
These spots develop into sores that break open and spread large amounts of
virus into mouth and throat
The rash starts on the face as a few macules, known as herald spots, and
spreads to the arms and the legs then to the hands and feet
The rash usually spreads to all parts of the body in just 24 hours
By the 3rd day of the rash the rash becomes raised bumps or papules
By the 4th day the bumps become vesicular, fill with a thick, opaque fluid and
often have depression in center that looks like a bellybutton (this umbilication is
a major distinguishing characteristic of smallpox especially from chickenpox)
Stages of Smallpox: Rash Phase







The fever will rise again at this time and remain high
until scabs form over the bumps
By the 6th or 7th day the lesions have become pustules:
they are sharply raised, typically round, tense, firm to
the touch (some describe them as feeling like BB’s
under the skin)
B/w 7 and 10 days the pustules mature and reach their
max size, and the umbilications remain throughout the
whole time
Although lesions are dense around the nose and
mouth, the majority of lesions are discrete (in some
cases the lesions become confluent)
At around 10 days of the rash the pustules begin to
form a crust
At about 14 days most of the lesions scab over and
some begin to separate
About 3 weeks after the onset scabs have separates
and the site of each lesion is depigmented and
eventually becomes pitted scars because of deeper
skin layer involvement
Stages of Smallpox: Rash Phase




The rash of smallpox has a
centrifugal distribution, meaning it is
most dense on the face, and more
dense on the extremities than on the
truck
The palms of the hands and soles of
the feet are involved in the majority of
cases
These characteristics are important in
differentiating smallpox from other
causes of rash illness
Another differentiating characteristic
of smallpox is that the lesions are all
in the same stage of development on
that part of the body (unlike
chickenpox) these stages of
development are: macules, papules,
vesicles, and crusted lesions



That was “ordinary” smallpox, now for
the
3
other
types
Modified: prodromal illness still occurs but is less severe
than the ordinary type, usually a fever but not as high, skin
lesions tend to evolve more quickly, are more superficial
and may not show the uniform characteristic of more
typical smallpox
Flat (or malignant) smallpox: sever with a high fatality rate;
in flat-type the lesions remain more or less flush with the
skin and don’t become raised, accounted for 5-10% of
cases in India, the prodrome symptoms are severe and
last 3-4 days, fever remains elevated throughout the
course of the illness and severe toxic symptoms, skin
lesions progress very slowly; lesions contain very little
fluid and are not umbilicated; the lesions are soft and
velvety to the touch, most cases are fatal
Hemorrhagic smallpox: sever and uncommon form of
smallpox that is almost always fatal, involves extensive
bleeding into the skin, mucous membranes and GI
tract, in the large Indian series it occurred in 2% of
cases, the prodrome has prolonged fever with little or
no remission, intense headache, restlessness,
extreme prostration and toxicity; death often occurs
between the 5th and 7th day of illness when only a few
maculopapular cutaneous lesions are present
When is a person contagious?



A person with smallpox is sometimes
contagious with the onset of fever (the
prodrome phase) but a person is most
contagious with the onset of the rash
Luckily, by the time a person gets the rash
they are so sick they can’t likely move around
the community
An infected person is contagious until the last
smallpox scab falls off
Clinical Diagnosis


There are 3 major criteria for diagnosing if a rash is indeed
smallpox:
 Prodrome that begins 1-4 days before rash onset and includes
fever over 101F, and at least one of the following symptoms:
prostrations, headache, backache, chills, vomiting, abdominal
pains
 Presence of classic smallpox lesions: firm, round, deep-seated
vesicles or pustules
 Lesions on the palms of the hands and/or soles of the feet
There are 5 minor criteria looked at for diagnosis of smallpox:
 Lesions are centrifugal distribution
 First lesions appear on the oral mucosa, face, or forearms
 Patient appears toxic
 Rash has slow evolution, each stage lasting 1-2 days
 There are lesions on palms of the hands and/or soles of feet
Common conditions confused with
Smallpox











Varicella (primary infection with varicella zoster virus)
Disseminated herpes zoster
Impetigo
Drug eruptions
Contact dermatitis
Erythema multiforme minor
Eyrthema multiforme (includes Steven Johnsons Syndrome)
Enteroviral infection esp. Hand, foot and mouth disease
Disseminated herpes simplex
Scabies and insect bites
Molluscum contagrosum
Laboratory Diagnosis of Smallpox




Culture on Egg chorioallantoic membrane
(CA): classical method; poxvirus grow on CA
Direct examination of vesicle or pustular
material: aggregations of virus may be seen
in certain cytoplasm upon staining
Tissue culture: growth in cultured cells
EM: negative staining is used to visualize
characteristic large brick shape of poxvirus




Relatively rapid
Can distinguish orthopox viruses from other
viral agents
Cannot differentiate between variola and
vaccinia viruses
May not be as sensitive as PCR-Based
methods
Laboratory Diagnosis of Smallpox


PCR Based method: In North America a positive test is
considered diagnostic for vaccinia virus unless medical or
epidemiologic evidence suggests otherwise
With slight modifications to the fluorescently labeled probe, this
assay can also be used to detect variola virus





Family specific primers are used first, then subgroup-specific primers
are used if the former is not successful in producing PCR product
DNA Probes: Assays using immobilized oligonucleotides in a
microarray have been developed to identify and discriminate
among orthopoxviruses
In situ hybridization of formalin-fixed tissues
Serology: Classical methods such as complement fixation and
gel precipitation commonly were used in the past; experimental
enzyme-linked immunoassays are currently being evaluated
Strain identification: A restriction fragment length polymorphism
assay (RFLP) has been developed by CDC using polymorphisms
found on 45 variola strains from 1939 to the 1970s
Laboratory Diagnosis



Lab diagnosis of smallpox is made by examination of material from a
skin lesions
For a patient who meets criteria for moderate risk, the most
important laboratory procedure is rapid diagnostic testing for
varicella zoster virus, or VZV
Most common method for detecting VZV is direct fluorescent
antibody, or DFA




This method detects VZV directly in cells using anti-VZV
antibody conjugated to fluorescein dye
This technique is very sensitive and specific but is critically
dependent on careful collection of material from lesion
Electron microscopy, detection of VZV DNA by polymerase chain
reaction testing of vesicular fluid or scabs, standard PCR, and
cytology smears are other rapid methods for detections of VZV
Ultimately, smallpox is a disease which can be easily diagnosed by
trained health workers without the need for laboratory support
Outcomes of Infection:





Those who survive usually have scars
If eye involvement then blindness could occur
Recovery results in long lasting immunity to
reinfection with variola virus; no evidence of chronic
or recurrent infection with variola virus
In fatal cases death usually occurs b/w the 10th and
16th days of illness
The cause of death from smallpox is not exactly
clear since the infection involves multiple organs;
perhaps uncontrolled immune response as well as
overwhelming viremia and soluble variola antigens
Treatment of Smallpox


Vaccine is administered up to 4 days after exposure
to the virus and before the rash appears, provides
protective immunity and can prevent infection or
ameliorate the severity of the disease
There is really no effective treatment, other than the
management of the symptoms




Adequate fluid intake (difficult)
Alleviation of pain and fever
Keeping skin lesions clean to prevent bacterial infection
Some compounds, such as Cidofovir, are under
investigation as chemotherapeutic agents
Vaccination




In 1796, Edward Jenner demonstrated that immunity to smallpox
could be produced by inoculating a human with material from a
lesion on the udder of a cow (cowpox); Jenner called this
material vaccine from vacca which is Latin for cow
At some time during the nineteenth century, the virus used for
smallpox ceased to be cowpox and was changed to vaccinia
Vaccinia is in the same family has cowpox and smallpox but
genetically different
In the early 1950s (150 years after Jenner’s vaccination came
out) an estimated 50 million cases of smallpox occurred in the
world each year, which feel to around 10-15 million by 1967 b/c
of vaccination
Vaccination




The smallpox vaccine is actual
live vaccinia virus, unlike other
vaccines which use dead virus;
for this reason the vaccination
site must be cared for to
prevent spread
Smallpox vaccine is
administered using a
bifurcated needle, not an
injection, unlike any other
vaccine
The bifurcated needle is
dipped into the vaccine and
then used to prick the skin 15
times in about 3 seconds in a
5mm radius area
It is administered into the
superficial layer of the skin
Vaccination







If vaccination is successful a red, itchy bump develops at the
vaccine site in 3-4 days; this is caused by the vaccinia virus
replicating in the basal cells of the epidermis producing a papule
surrounded by erythema
In the first week the bump becomes a blister, fills with pus, and
begins to drain
A person is considered protected with the development of a
pustule like this at the vaccination site
During the second week the blister begins to dry and a scab
forms; the scab then falls off leaving a scar
Most people experience the side effects of a sore arm, fever, and
body aches and axillary lymphadenopathy (3-5 days after
vaccination)
1st time vaccinators have a stronger reaction than those who are
re-vaccinated
Because the virus is live it can be spread to other parts of the
body or to other people so great care must be given to the
vaccination site to prevent this
Vaccination








The vaccine provides a high level of immunity for 3-5 years and
decreasing immunity thereafter
If a person is re-vaccinated the immunity lasts even longer
Studies show that even 30 years after a vaccination, while a person may
not be protected against smallpox they have a less severe disease
The vaccine has been effective in preventing smallpox in 95% of people
vaccinated
Evidence for a brisk cell-mediated immune response has also been
detected
It is believed that healing of the vaccinia infection is associated with intact
cell-mediated or T-cell and cytokine immune competence, and that
viremia is defended by an intact antibody or B-cell immune competence
If the vaccine is given in 1-2 days after exposure to smallpox it is effective
in preventing smallpox or mitigating the symptoms of those who have
been exposed
The fatality rate among people vaccinated less than 10 years before
exposure was 1.3%; it was 7% among those vaccinated 11-20 years prior,
and 11% among those vaccinated 20 or more years prior to infection;
52% of unvaccinated people died
Vaccination







The antibodies induced by the vaccinia vaccine cross protect for
other Orthopoxviruses (including monkeypox, cowpox, and
smallpox)
Three different smallpox vaccines are available (or will soon be) in
the U.S.
All 3 contain the New York City Board of Health strain of live
vaccinia virus
Dryvax is the currently licensed vaccine; it was produced by Wyeth
Lederle in the early 1980s from calph lymph containing live
vaccinia virus; the vaccine is provided as a freeze dried powder in
a multi-dose vial
Dryvax is produced by infecting a calf with vaccinia and then
collecting the lymph from the virus filled pustules on the calf’s
udder
Dryvax contains the antibiotics polymyxin B, streptomycin,
tetracycline and neomycin
A second vaccine produced years ago by Aventis Pasteur would
be available in the case of an emergency
Vaccination






New smallpox vaccines also contain live New York City Board of
Health vaccinia virus, but are produced using cell culture
technology rather than live animals; these vaccines may also be
distributed as a freeze dried powder but do not contain antibiotic
In October 2002 Acambis-Baxter Laboratories began preparing
Tissue culture cell vaccines
The two types of cells being used to cultivate the vaccinia virus
are: Vero monkey kidney cells, and human fibroblast cell line
(MRC5)
It is thought that these cell cultured vaccines will have less sideeffects than the calph-lymph vaccine
The other vaccines currently being developed: Modified vaccinia
Ankara (MVA) vaccine, Japanese strain LC16m8 vaccine
Current supply: there are 14.8 million doses of DryVax available
and 85 million doses of the Aventis product, and when the
Acambis vaccines are available there will be an additional 209
million doses available
Who Should Not Get the Vaccine?

The vaccine is contraindicated for:
 Persons who have experienced a serious allergic reaction to a prior
dose of vaccine or to a vaccine component
 Persons with significant immunosuppression from any cause (HIV,
transplant, receiving treatment for cancer) or anyone with an
immunosuppressed person in their household
 Pregnant women and persons with a pregnant person in the
household
 Breastfeeding women
 Children under 12 months; in fact the Advisory Committee on
Immunization Practices (ACIP) advises against non-emergency
vaccination in children under 18
 Persons with any heart problems, stroke or transient ischemic attack,
high blood pressure, high cholesterol, or diabetes
 Persons with any sort of skin condition
 Persons with inflammatory eye diseases requiring steroid therapy
4 Main Complications of Vaccination

Ecxema vaccinatum





Progressive vaccinia (vaccinia necrosum)











Occurred in otherwise healthy individuals
Characterized by development, from 6-9 days after vaccination, of a generalized rash, sometimes covering whole
body
Prognosis good
Occurred in 143 persons with no deaths
Postvaccinial encephalitis


Occurred in persons who suffered from an immune deficiency or with humoral or immune globulin deficiencies
Local lesion at the vaccination site failed to heal; all lesions spread progressively until the patient died, usu. 2-5
months later
Occurred in 11 person, with 4 deaths
Generalized vaccinia


Occurred in vaccinated persons or unvaccinated contacts who were suffering from or had a history of eczema
An eruption occurred at the sites on the body that were at the time affected by eczema or had been
Symptoms severe; eruptions became intensely inflamed
Occurred in 74 persons with no deaths; 60 cases from contact with vaccinated persons with 1 death
Most serious complication
Occurred in 2 forms: 1. seen in infants under 2 years old, had violent onset, characterized by convulsions 2. seen
in children older than 2 years had abrupt onset, with fever, vomiting, headache, and malaise
Fatality rate was about 35%, with death usually occurring within a week
Occurred in 16 persons with 4 deaths
Other complications: congenital vaccinia (infection of fetus), accidental implantation (autoinoculation
of any disrupted skin), vaccinia keratitis (autoinoculation of the eye and prior eye disease)
Finally, in the past 1000 for every 10 million people vaccinated for the first time experiences reaction
that was serious but not life threatening; b.w 14-52 people developed life threatening symptoms
Eczema Vaccinia
Progressive Vaccinia
Generalized Vaccinia
Progressive Vaccinia
Developed Erythema Multiforme 1
mo. After vaccine
Secondary herpes infection
Contact Vaccinia
Treatments for Complications from
Vaccination







Vaccinia Immune Globulin (VIG) is a sterile solution of the immunoglubulin
fraction of plasma from person who was vaccinated with smallpox vaccine
VIG was produces in the 1960s and it contained a high titer of anti-vaccinia
neutralizing antibody
VIG has shown to work in the treatment of smallpox vaccine adverse
reactions caused by continued replication of vaccinia virus, such as the
above mentioned complications
VIG is available from CDC under an investigational new drug protocol
Cidofovir is an antiviral medication (not previously used in humans) used to
treat vaccinia infection; it is considered a second line therapy for smallpox
vaccine adverse reactions
A new intravenous formulation of VIG is being produces to support
treatment of adverse events that may result from smallpox vaccination
VIG is not recommended for mild instances of inadvertent inoculation, mild
generalized vaccinia, erythema multiform, post-vaccination encephalities,
and isolated vaccinia keratitis
Vaccinations Now


Routine vaccination in the U.S ended in 1972 for children and 1976 for
healthcare workers
On December 13, 2002, President Bush announced the following US
policy:





Smallpox vaccinations are required for military personnel; according to the
Department of Health and Human Services (DHHS), approximately 500,000
military personnel will be vaccinated.
Smallpox vaccinations are recommended for smallpox response teams
comprised of public health staff and healthcare workers likely to be involved
in the initial care of any patients with smallpox.
Smallpox vaccinations also are being offered to other healthcare workers
and to first-responders (including police officers, firefighters, and emergency
medical technicians).
Smallpox vaccinations likely will be made available to the general public on a
voluntary basis once large stockpiles of the vaccine are licensed.
Small Response Teams: Department of Health and Human Services will
work with state and local governments to form volunteer smallpox response
teams who can provide critical services in the event of a smallpox outbreak
Vaccinations Now


On April 30, 2003, the President signed into
law the Smallpox Emergency Personnel
Protection Act of 2003
The law establishes a no-fault program to
provide benefits and compensation to certain
individuals (ie, healthcare workers and
emergency responders) who are injured as a
result of administration of smallpox
vaccination or other smallpox
countermeasures
Vaccinations Now


In a report released in August 2003, the Institute of Medicine (IOM)
Committee on Smallpox Vaccination Program Implementation made
several recommendations regarding offering smallpox vaccination to
the general public
Specifically, the Committee recommended that CDC proceed by:



Conducting brief quantitative surveys to determine public interest and desire for
smallpox vaccine; these surveys should include public and private health
agencies as well as the general public, in order to understand the potential scope
of public interest.
Determining the budgetary and other requirements that would meet the demand
noted.
Identifying, monitoring, and referring people to existing or planned smallpox
vaccine clinical research trials or other well-structured clinical programs that meet
the basic requirements of medical and public health ethics, including assurances
for safety of vaccinees and their contacts, acceptable balance between risk and
benefit, and acceptable distribution of scarce public health resources to meet all
preparedness as well as other public health goals; The committee encourages
CDC to consider utilizing a pilot program or some other means of evaluating the
initial experiences with this effort.




During the smallpox eradication campaign (1970s) and during
smallpox outbreaks in the past, a "ring vaccination" (used in
1967) strategy has been followed
This approach is incorporated into the current CDC Smallpox Plan
Ring vaccination essentially involves creating a circle of
vaccinated persons around each case to interrupt the chain of
transmission.
The strategy involves the following steps:





Rapid identification and isolation of all smallpox cases
Identification and vaccination of contacts of smallpox cases
Monitoring contacts for development of fever and isolating them if fever
occurs
Vaccination of household members of contacts if no contraindications to
vaccination exist
In addition to ring vaccination, rapid voluntary vaccination of a
large population may be required to:



Supplement priority surveillance and containment control strategies in areas
with smallpox cases
Reduce the "at-risk" population for additional intentional releases of smallpox
virus if the probability of such occurrences is considered significant
Address heightened public or political concerns regarding access to
voluntary vaccination
Management of an Outbreak







Surveillance of smallpox infection is probably easier than for any
other infectious disease because of the distinctive rash, which is
wholly characteristic
Containment involves efficient detection of cases and
identification and vaccination of contacts
Patients diagnosed with smallpox should be physically isolated
All specimen collectors, care givers and attendants coming into
close contact with patients should be vaccinated as soon as
smallpox is diagnosed as the cause of an outbreak
Medical care givers, attendants, and mortuary workers, even if
vaccinated, should wear gloves, caps, gowns, and surgical
masks
Contaminated clothing and bedding, if not incinerated, should be
autoclaved or washed in hot water containing bleach
Fumigation of premises may be done with formaldehyde
Isolation Precautions


Airborne and Contact Precautions in addition to Standard Precautions
should be implemented for patients with suspected smallpox.
Airborne Precautions:




Place the patient in a private room with negative air-pressure ventilation (minimum 6 air
exchanges/hr).
Use external air exhaust or high-efficiency particulate air (HEPA) filters if the air is
recirculated.
Keep the door to the room closed.
Contact Precautions:






Place the patient in a private room if available.
If a private room is not available, place the patient in a room with a patient who has
active infection with the same organism (ie, cohort patients with smallpox).
Wear gloves when entering the room, change gloves after having contact with
infectious material, remove gloves before leaving the room, and immediately wash
hands using an antimicrobial agent.
Wear a gown when entering the room if clothing will have significant patient contact;
remove the gown before leaving the room.
Move and transport the patient for essential purposes only. If transport is necessary, a
mask should be placed on the patient.
When possible, dedicate the use of noncritical patient-care equipment.
Autopsy and Burial Procedures



According to WHO "Cadavers should be cremated, in a properly
designed facility, whenever possible and all persons coming in
contact with them should be vaccinated or at least placed on
daily fever watch. Body bags treated with hypochlorite bleach
can also be used."
Consideration should be given to using sealed systems when
burying patients who have died of smallpox. An example of the
type of system that can be used to seal remains prior to placing
them in a casket for burial is the BioSeal Facility System,
produced by Barrier Products
This system utilizes a poly-aluminum foil–extruded laminate
material that when used with a heat sealer will provide Level 1
containment for all gases, fluids, vapors, and odors associated
with the transport and storage of human and animal remains.
BIOTERRORISM
-The Center for Disease Control and Prevention (CDC) divided biological
agents that are critical biothreat agents into 3 categories ( A, B,C ) based upon
their risk for causing mass casualties in the event of bioterrorist atack.
-Variola ( smallpox) wass classified as a category A agent:
* poses a risk to national security (it can be easily disseminated or transmitted
person to person)
* causes high mortality, with potential for major public health impact
* might cause public panic and social disruption
* demands special action for public health preparedness
- Variola requires Lab. Biosafty Level 4
BIOTERRORISM
- Smallpox is a disease that followed humanity for thousands of years until ~30 years ago.
It was possible to eradicate smallpox, because an effective live vaccine from
crossreacting virus – vaccinia was developed.
The global vaccination program was financed and managed by the World Health
Organization (WHO) and the official eradiction announcement was made in 1980.
- Over 20 years have passed since general vaccinations stopped and very few people
are protected against the disease today.
- General vaccination, due to the number of complications that can be expected,
is probably not possible with the present vaccines, except in an emergency.
There is ongoing research in order to develop new vaccines.
Tengell et al. Smallpox-eradicated, but growing terror threat.
Clin Microbiol Infect (2002), 8: 504-509
BIOTERRORISM
- It was formerly thought that smallpox was not very suitable for biological warfare,
because it was too infectious. An attack would entail a high risk of a worldwide
epidemic, striking even the populations of the attackers.
- Terrorists generally lack the means for vaccinating large groups of people and
have less opportunity to run large – scale virus cultures. Thus, it has been
considered far more probable that they would prefer bacterial resource such as
anthrax, which entails less risk of uncontrollable epidemics.
-Terrorist movement or the military command of a state could draw a conclusion
that an attack with variola in the USA could allow the epidemic to remain local
because of the expected vigorous countermeasures. If the risk of a worldwide
epidemic seems small, an attack might be an attempt.
- Additionally, we have now seen that terrorist can be extremely fanatical.
The attacks on September 11th, 2001 demonstrated the great ruthlessness and
considerable resources of some terrorists.
Atlas R.F. Bioterrorism: From Threat to Reality. Annu Rev.Microbiol.(2002)56: 167-85
BIOTERRORISM
Why is variola virus considered an ideal bioterrorist weapon:
-
-
It is highly transmissible by the aerosol route from infected to susceptible
people;
The civilian populations of most countries contain a high proportion of
susceptible persons;
Smallpox is associated with high morbidity and about 30% mortality;
Initially, diagnosis of a disease that has not been seen for 20 years would
be difficult;
At present, other than the vaccine, which may be effective in the first few
days post-infection, there is no proven drug treatment available for
clinical smallpox;
It induces panic;
Mahy,B.W.J. An overview on the use of a viral pathogen as a bioterrorism agent: why smallpox?
(2003) Antiviral Research 57: 1-5
BIOTERRORISM
-Vaccinia virus, if released as an aerosol and not exposed to UV lights may
persist for as long as 24 hours. It is belived that variola virus would exhibit
similar properties.
-Vaccinia virus, if released as an aerosol, is almost completely destroyed within
6 hours in an atmosphere of high temperature (31C – 33 C) and
humidity (80%). In cooler temperatures (10 C- 11 C) and humidity (20%), nearly
two thirds of a vaccinia aerosol survives for as long as 24 hours. It is belived that
variola would behave similarly.
-Virus in scabs is more durable. At a temperature of 35 C and 65% humidity ,
the virus can persist for 3 weeks. At cooler temp. (26 C) the virus has survived
for 8 weeks at high humidity and 12 weeks at a relative humidity less than 10%
-Dutch investigators demonstrated that it was possible to isolate variola virus from
scabs that had been sitting on a shelf for 13 years.
-Vaccinia / Variola viruses are sensitive to disinfectants like hypochlorite (bleach)
and ammonia – are effective for cleaning surfaces
Henderson,D.A. et al. Smallpox as Biological Weapon. (1999) JAMA, 281 : 2127-2137
BIOTERRORISM
Bill Patrick, a former bioweaponeer who worked at Fort Detrick, Md. ,
before the American offensive biological weapons program was dismanteled
in 1969, says:
- Bioweaponeers in the US program had begun weaponizing smallpox before
the US biological weapons offensive effort was halted.
- “We made a beautiful powder for smallpox. We used chemical to protect it
during dissemination and aerozolation”
- A gram of powdered virus ( equivalent of a quarter of a teaspoon of baking
powder) would infect 100 people.
http://www.mercola.com/fcgi/pf/2001/nov/14/smallox.htm
BIOTERRORISM
- There are only two official stocks of smallpox virus that are held:
1. USA: at CDC in Atlanta, Georgia
2. Russia: at Vector in Novosibirsk, Siberia (moved in 1984 from Moscow)
-Dr. Kenneth Alibek (formerly Kanatjan Alibekow),
a native from Kazakhstan, medical doctor,
and officer of the Red Army,
he worked from 1975 to 1992 for the Soviet Biopreparat
complex ( an ostensibly civilian pharmaceutical production
association that was actually a top-secret branch of
the Soviet biological weapons program).
Dr.Alibek was the Chief Scientist and first deputy director
of Biopreparat in 1988. He defected to the USA in 1992.
BIOTERRORISM
- His book ( with Stephen Handelman) Biohazard: The Chilling True Story of
the Largest Covert Biological Weapons Program in the World
(Random House 1999)
describes his experience with Russian biological warfare (BW) activites.
-In 1998, Dr.Alibek visited the Center for Nonproliferation
Studies in Monterey and met with the staff for the ChemiCal and Biological Weapons Nonproliferation Project
(CBWNP). He was interviewed by Jonathan B. Tucker,
CBWNP Director. Additionally he released a statement,
where he discussed the BW situation in Russia in a
great detail.
1.The Soviet Union had the most efficient, sophisticated,
and powerful offensive BW programs in the world. It
developed a completely new class of weapons based on
genetically modified agents, eg. during the 1980’s they
developed antibiotic-resistant strains of plague, anthrax,
and tularemia.
BIOTERRORISM
2. Russia researched the genetic alteration of smallpox.
* “In 1990 and 1991, we engineered a smallpox at Vector.
It was found that several areas of the smallpox genome
can be used for the introduction of some foreign genetic material.
The first development was smallpox and VEE. VEE,
or Venezuelan equine encephalitis, is a brain virus.
It causes a severe headache and near-coma, but it is generally not lethal.
Alibek said that the researchers spliced VEE into smallpox .
The result was a recombinant chimera virus: Veepox.”
* More recently, Alibek claims, the Vector researchers may have created
a recombinant Ebola-smallpox chimera. One could call it Ebolapox.
ABC News - Dec. 3, 2002 - by Brian Ross
http://www.sierratimes.com/cgi-bin/warroom/topic.cgi?forum=6&topic=39
BIOTERRORISM
EBOLAPOX
*Ebola virus uses the molecule RNA for its genetic code, whereas smallpox uses DNA.
Alibek believes that the Russian researchers made a DNA copy of the disease-causing
parts of Ebola, then grafted them into smallpox. Alibek said he thinks that the Ebolapox
virus is stable -- that is, that it will replicate successfully in a test tube or in animals –
which means that, once created, Ebolapox will live forever in a laboratory,
and will not uncreate itself. Thus a new form of life may have been brought into the
world.
*"The Ebolapox could produce the form of smallpox called blackpox," Alibek says.
Blackpox, sometimes known as hemorrhagic smallpox, is the most severe type of
smallpox disease. In a blackpox infection, the skin does not develop blisters. Instead,
the skin becomes dark all over. Blood vessels leak, resulting in severe internal
hemorrhaging. Blackpox is invariably fatal. "As a weapon, the Ebolapox would give the
hemorrhages and high mortality rate of Ebola virus" Alibek said.
ABC News - Dec. 3, 2002 - by Brian Ross
http://www.sierratimes.com/cgi-bin/warroom/topic.cgi?forum=6&topic=39
BIOTERRORISM
Mousepox
- Mark Buller, a scientist, who is funded by the US government,
deliberately created a deadly form of mousepox, which is closely related to the smallpox
virus, through genetic engineering. Reason: to study what bioterrorists might do.
-Another team ,Ramshaw's team, continued research by adding a gene called IL-4
to the modified mousepox. He expected that doing this would boost antibody production,
but instead, the new mousepox virus was far more lethal, killing 60 percent of vaccinated
mice.
Debora Mackenzie. US develops lethal new viruses.(2003) New Scientist
http://www.cals.ncsu.edu/course/gn301/Supplements/Mousepox_Virus_SR3.html
- Additionally, Alibek stated :
* No dry smallpox weapon was developed, just one in a liquid form.
* Some supplies of smallpox (also plague and anthrax) were manufactured,
stored, and stockpiled. Immediately after receiving an order it would take just
two or three days to transfer these agents from storage tanks into cluster
bomblets and spray tanks. Each 500kg cluster bomb contained more than 100
bomblets. The bombs would be stored in the refrigerated bunkers until use.
The Nonproliferation Review / Spring-Summer 1999
http://cns.miis.edu/pubs/npr/vol06/63/alibek63.pdf
BIOTERRORISM
- Q: What was the logic of developing an agent like smallpox, which is so contagious
that it could create a huge pandemic?
A: Unfortunately, it is a normal progression to develop more powerful weapons. Why,
for example, did we develop a 100-megaton hydrogen bomb when both superpowers
had 10-megaton and 20- megaton bombs?
-For the Soviet Union, the main doctrine was to use biological weapons in so – called
total wars involving possible mutual destruction between the USA and the Soviet Union
and their allies
-Given, however, the economic situation in the former Soviet Union, the incentive
to sell equipment and knowledge suitable for biological weapons production without
regard to their eventual use is great both for the government and for individual scientists
and businessmen. The Russian government has long been short of funds, and its
biotechnology arena has also been adversely affected. Many of its scientist are
unemployed; those that are employed are paid poorly or not at all.
The Nonproliferation Review / Spring-Summer 1999
http://cns.miis.edu/pubs/npr/vol06/63/alibek63.pdf
BIOTERRORISM
CDC plan and guidelines for containment and vaccination in the event of
smallpox bioterrorist attack:
• The plan calls for isolation of confirmed or suspected smallpox patients to limit
the potential exposure of nonimmune persons.
• Vaccinia vaccine would be recommended for persons who were exposed to
the initial release of the virus:
- Persons who had face-to-face, household, or close-proximity contact (~2m) with
confirmed or suspected smallpox patients
- Laboratory personnel involved in the collection or processing of clinical specimens
from confirmed or suspected smallpox patients
- And other persons who have an increased likelihood of contact with infectious
materials from a smallpox patient
Atlas R.F. Bioterrorism: From Threat to Reality. Annu Rev.Microbiol.(2002)56: 167-85