Fauzia Manzoor, MD
The
worldwide eradication of smallpox is without question one of the greatest
achievements in the fields of medicine and public health. This feat would have
most certainly been impossible without global cooperation, the use of an
effective vaccine, and a careful epidemiologic surveillance program. The world
has not seen a case of smallpox since 1977, and the last case in the United
States occurred in 1949. Smallpox was produced as a weapon by several nations well
past the 1972 Bioweapons convention that prohibited such actions. The potential
for intentional release of a now eradicated, deadly communicable disease in a
basically non-immune population is truly frightening. This horrific possibility
is difficult for some to imagine.
Recent reports of
smallpox threats have prompted a serious assessment of clinical strategies in
the event Smallpox being used as a Bioweapon. Few natural or intentional
threats generate more concern among emergency management planners, physicians,
nurses, and toxicologists in this country than the use of biological agents as
an act of war against citizens of the United States.
History
Smallpox
is an orthopox virus that affects primates, particularly man. Smallpox was
described more than 2000 years ago. It apparently originated in India or
western Asia and then spread to China. About 700 AD, smallpox spread to Japan,
Europe, and North Africa. European colonization in the Americas and Africa was
associated with extensive epidemics of smallpox among native populations in
these continents in the 1500s and 1600s.
Smallpox
was used as a biologic weapon in the United States during the French and Indian
War. In modern times, however, smallpox was considered an unlikely agent of
biowarfare because there was a high level of population immunity to the virus,
there is an effective vaccine, and the use of the vaccine can rapidly control
outbreaks.
Theoretically, the virus now exists in only two laboratories in the world in the United States and in Russia. Were smallpox virus released as an act of terrorism, the results could be catastrophic. A large proportion of the adult population and all of the pediatric population have no immunity. The CDC says it has access to enough vaccine to effectively respond to an outbreak in the United States. A Dec. 13, 2002, document says the United States currently has sufficient quantities of the vaccine to vaccinate every person in the country in an emergency.
Worldwide
Eradication:
Certain
military and civilian personnel deployed to high-threat areas are being vaccinated. Health
care workers are being asked to volunteer to receive the vaccine. Vaccination
is not currently recommended for the general public.
Types:
There
are two types of smallpox; variola major, with a mortality of 20-30% in
unvaccinated individuals; and variola minor, with a mortality of about 1%.
Infection with variola minor protects against subsequent infection with variola
major. The intranasal or intradermal introduction of dried smallpox variola
minor scabs was used to prevent smallpox nearly 1000 years ago. Subsequently,
Jenner substituted intradermal cowpox, a milder Orthopox virus infection, to
prevent smallpox in 1798. Vaccinia, a related Orthopox of uncertain origin, has
replaced cowpox for vaccination.
Transmission:
The
virus can be transmitted by face-to-face contact, secretions, and aerosols. It
is a durable virus and can exist for long periods outside the host. It is
remotely possible that it still is living outside of the repository labs.
Fortunately, aerosol vaccinia (and probably variola virus) is deactivated
within 24 hours by ultraviolet light and heat. By the time casualties present
to the emergency department with clinical symptoms, they would not need to be
decontaminated.
Incubation
period:
Presentation:
The
majority of smallpox cases present with a typical rash that is most dense on
the face and extremities. The lesions appear during a one- to two-day period
and evolve at the same rate. It should be differentiated from chickenpox.
Chickenpox:
In chickenpox [varicella], new lesions appear
in crops and lesions of different ages are present in adjacent areas of the
skin. Chickenpox lesions are more numerous in the trunk than in the
extremities.)
Hemorrhagic
smallpox:
Some
patients will develop disseminated intravascular coagulopathy (hemorrhagic
smallpox). Hemorrhagic smallpox is uniformly fatal. The illness has a somewhat
shortened incubation period and is accompanied by high fever and head, back,
and abdominal pain. Shortly after the pain starts, the patient develops a dusky
erythema, followed by petechiae and flank hemorrhages into the skin and mucous
membranes. Death occurs by the fifth or sixth day after the rash. Pregnant
women are particularly susceptible to this variant of smallpox. Hemorrhagic
cases of smallpox were frequently misdiagnosed as meningococcemia.
Malignant smallpox:
Another variant of smallpox is malignant smallpox, a “flat-type” smallpox associated with severe toxemia and high mortality. In the malignant form, the abrupt onset and shortened incubation period are similar to the hemorrhagic variant. In malignant smallpox, the skin lesions develop slowly and do not progress to the pustular stage, hence the description as “flat.” The skin develops the appearance of a fine-grained, reddish-colored crepe rubber. Hemorrhage is sometimes noted within the skin. These flat lesions disappear without scabs in survivors. Some patients will have desquamation of large areas of affected skin. Diagnosis of this variant of smallpox may be quite difficult until viral studies are available. These patients were frequently misdiagnosed because the appearance was atypical.
Monkeypox:
Monkeypox is a milder form that has been reported in the Democratic Republic of the Congo (formerly Zaire). The clinical picture is indistinguishable from smallpox. The case fatality rate of verified monkeypox in patients who were not vaccinated against smallpox was 11% (15% for children younger than age 5). As with smallpox, the disease is significantly milder in vaccinated persons. A major differential point of monkeypox is the presence of large cervical and inguinal lymph nodes. These are uncommon in both smallpox and chickenpox.
Sequelae of Small pox:
The
most common sequelae of smallpox are scarring, particularly facial. Rarely,
smallpox may cause blindness due to ocular involvement (keratitis). Other
complications include smallpox pneumonia and arthritis (may have permanent
joint deformities).
Seasonal Occurrence:
The
seasonal occurrence of smallpox is similar to chickenpox and measles. Its
incidence is highest during the winter and early spring. Large outbreaks in
natural smallpox were rare during the summer.
Infective Period:
Transmission of smallpox is slowed because
the disease usually is not infective until the patient has been confined to bed
with high fever and rash appears. Unfortunately, this means that in-hospital
infectivity is quite high. (In Germany, a smallpox patient with a cough,
isolated in a single room, infected persons on three floors of a hospital. This
infectivity would be increased when diagnosis is delayed, as in malignant or
hemorrhagic smallpox.
In
natural smallpox, the disease is infective from the appearance of the rash
through the first 7-10 days of the rash. An aerosol release of variola virus
would disseminate widely, since the virus is stable in aerosol and the infectious
dose is quite small.
During
epidemics in the 1960s and 1970s in Europe, as many as 10-20 second-generation
cases were infected from a single case.
The illness associated with variola minor generally is less severe and
fewer systemic symptoms are seen. The rash often is sparse. This presentation
also may be seen in those who have residual immunity from prior vaccination. In
the partially immune patient, the rash is atypical and scant. The evolution of
the lesions may be more rapid.
Vaccinia
produces a localized pustular lesion at the site of inoculation, with localized
lymph node involvement. When administered to immunocompromised patients,
vaccinia may become progressive. Generalized vaccinia occurs 6-9 days after
inoculation. The patient also accidentally may spread vaccinia to other body
sites (e.g., ocular vaccinia). Postinfectious encephalitis following
inoculation with vaccinia is possible. The most important clue about
disseminated vaccina is a vaccination or exposure to a recently vaccinated individual.
Diagnosis:
Like
many viral diseases, the diagnosis is best made by clinical impression.
Smallpox has an incubation period of 10-14 days followed by the abrupt onset of
fever, headache, malaise, and backache. Three to four days after the onset of symptoms,
a characteristic rash appears on the oropharynx, face, forearms, and hand. The
rash evolves from macules to papules to vesicles and finally to pustules. After
8-9 days, the pustules will rupture and crust over. The rash has profuse
involvement of the face, forearms, and lower legs. The trunk and abdomen
usually are spared.
Routine labs are not helpful, although leukopenia is frequent. Clotting factors may be depressed and thrombocytopenia may be found. Diagnosis may be made with immunofluorescence, electron microscopy, or culture. Orthopox viruses are large, brick-shaped viruses with a single double-stranded DNA molecule. A recently developed polymerase chain reaction (PCR)-based assay of the hemagglutinin gene allows classification of all of the species of the orthopoxvirus family.
Therapy is entirely supportive (IV, fever control, antibiotics to prevent secondary
bacterial infections. Three compounds (cidofovir, its cyclic derivative,
and ribavirin) have significant antiviral activity against variola. These
medications have not been used in treatment and may or may not be effective.
Vaccination:
Vaccination
administered within four days of first exposure has been shown to offer some
protection against acquiring the infection and significant protection against a
fatal outcome. An emergency vaccination program should include all health
workers at clinics or hospitals that may receive such patients and all disaster
workers such as EMS, hospital staff, police, public health staff, and mortuary
staff. These personnel should be vaccinated as soon as the first case is diagnosed,
irrespective of prior vaccination status. Vaccination should be considered for
any other persons who would be responsible for patient care during a suspected
outbreak of smallpox and for the investigation and control of suspected
outbreaks of smallpox.


Prophylaxis:
Prophylaxis
against smallpox has been available since the time of Jenner and is well
documented. Since smallpox is presumed
to have been eradicated worldwide, there is no recommendation or requirement
for routine vaccination of the
general public, however military personnel deployed to high-risk areas are
being vaccinated, and there currently is a voluntary vaccination program for
potentially at-risk health care workers.
|
Disease |
Vaccine |
Availability |
|
Small
Pox |
Given
prior to exposure. Inoculation provides almost 100% protection against the
disease. It is most effective after 4 days after exposure. People who were
previously vaccinated will have protection and have faster onset of
protection when revaccinated. Some antiviral may also may be effective. |
The
CDC says that United States has enough vaccine for every person in the
country in the event of emergency Contraindicated
for immunosuppressed individuals. Not
recommended since 1980. |
Those who have been vaccinated at some time in the past will usually have an accelerated immune response. Those who have been previously vaccinated may be somewhat safer in situations with close patient contact.
Isolation:
Isolation of all contacts of exposed patients would be quite difficult. If the weaponized smallpox is like the natural variety, patients are not infective until the onset of the rash. A practical strategy argues that all contacts should have their temperatures taken daily, preferably in the evening. A fever of 101°F (38°C) or higher should be cause for isolation of the contact until clinical or laboratory diagnosis of the disease or other cause of the fever. All close contacts should be promptly vaccinated. Experience during the smallpox global eradication program showed that patients who had no rash did not transmit infection, so “isolation on fever” is a logical step. The malignant (flat) form of the rash and the hemorrhagic form of the rash are just as infective as the classic rash.
Decontamination:
The
person-to-person infectivity, high mortality, and stability of the virus make
variola a potential BW threat. Other animal poxviruses could be easily
genetically engineered to be virulent in humans.
A
human cell culture-derived vaccinia is being developed at Fort Detrick.
Smallpox vaccine is not without complications, since vaccinia can be lethal to immunosuppressed patients. Indeed, among 5.5 million vaccinations done during the 1961-1962 outbreaks of smallpox in the United Kingdom, vaccination caused at least 18 deaths. With transplantation, more aggressive cancer chemotherapy, use of high-dose steroids, and HIV infections, the number of immunosuppressed individuals has grown markedly since 1952. Each of these patients is at mortal risk from the prophylaxis of smallpox.
Objects
in contact with a contaminated patient need to be cleansed with live steam or
sodium hypochlorite solution (or other standard disinfectants). The virus may
remain viable for extended periods of time in clothing or linens. Bed linens
and dressing material should be autoclaved before laundry or disposal.
Although a vast array of
first responders, including elements of the military, police, and fire
departments, emergency medicine services, and hazardous materials units have
been preparing to respond to such emergencies, relatively few practitioners
have been involved in comprehensive efforts to defend against possible acts of
bioterrorism.
Especially
in a covert attack, however, primary care practitioners, emergency medicine
specialists, and departments of pharmacy—which would be responsible for
maintaining adequate inventories of antidotes, vaccines, and antimicrobials
required for such a contingency—would play a front-line role in the detection,
evaluation, and response to this threat. Formal educational curricula informing
clinicians about the likely agents of bioterrorism are essential to ensure that
cases are identified, reported, treated, and monitored as rapidly and efficiently as possible.
As
practitioners are well aware, the current Smallpox threat remains a fluid,
uncertain situation. In light of rapid changes in both our understanding and
approach to bioterrorist activities, and as new patterns of infection are
recognized, the treatment options, epidemiology, and approaches to management and prophylaxis of Smallpox
are being closely monitored by medical, military, and governmental agencies.
This
has important implications for clinical practice. Because diagnostic and
management strategies are under constant review and evaluation, clinicians are
advised to consult and monitor the most recent recommendations, reports, and
advisories issued by such expert bodies as the Centers for Disease Control and
Prevention and the Food and Drug Administration, as well as such publications
as the Morbidity and Mortality Weekly Report (MMWR) and Biological Warfare Defense General Information Sheet. Regional
poison control centers also are excellent sources of current information
regarding bioterrorist threats, and also may be accessed for up-to-date
information.
In the event of a covert biological agent like Smallpox attack, ED practitioner awareness would most likely occur when increased numbers of patients present with clinical symptoms of a suspicious nature.
Because early presentation of Smallpox has nonspecific clinical features, early recognition and timely intervention may be difficult, and therefore heightened awareness is essential.
Suspicion. Before
the medical personnel approach a potential biological casualty, they need to
ensure that they are appropriately protected. The rescuer will do little good
if he or she becomes infected and is a subsequent casualty. HEPA-filter masks
will provide adequate protection against inhalational biological warfare (BW)
threats. Gowns and gloves complete the ensemble.
The
initial assessment of the patient with a potential Smallpox infection often is
hasty and may cloud the issue. In the early phases, it might mimic common
endemic problems. If the
clinician is not asking how this patient may be different from other patients
with similar illnesses, the patient may not be identified and the window for
effective therapy may be missed.
Stabilization
and Decontamination. Airway, breathing, and
circulation problems should be addressed before any specific management is
contemplated. Physical examination should concentrate on pulmonary and cardiac
systems. Unusual dermatologic and vascular findings should be documented and
photographed.
The
incubation period of Smallpox makes it unlikely that decontamination will be
warranted. If the exposure is quite recent and known, then decontamination with
soap and water or 0.1% bleach may be appropriate.
Diagnosis.
Questions about
food and water sources, vector exposure, immunization history, travel history,
occupation, and illnesses in other family members may offer clues to the
clinician and should be recorded in meticulous detail.
The
amount of expertise available to the emergency clinician will vary with the
medical practice. At tertiary care centers; a full range of laboratory
capabilities should help with a prompt diagnosis. At primary care centers,
specimens should be obtained and forwarded through public health channels or
reference laboratories.
The
clinical laboratory should be notified that these specimens might represent BW
agents so that utmost precautions can be taken and the use of optimum culture
media can be planned.
While awaiting the results of the laboratory diagnosis, the clinician must formulate a clinical diagnosis.
Patients
with smallpox or other viral illness will not suffer significant harm from
empiric antibiotics.
Final
treatment, including protection for the involved health-care workers, must be predicated
on an accurate diagnosis.
Notification.
Hospital
administration, public health officials, and law enforcement must be notified
about the possibility of a biowarfare incident. It is far better to call and
activate systems early so that adequate medical supplies are available.
Public Health management and
details on current planning efforts
In
response to this potential public health catastrophe, U.S. public health, as
well as Department of Defense, authorities have directed the reintroduction of
a smallpox vaccination program. The general civilian population has not
received smallpox vaccinations since 1972; however, the Department of Defense
continued to inoculate non-immunized recruits until 1990. So, the
reintroduction of a highly successful, time-proven immunization program should be a simple, uncomplicated
decision.
The
smallpox vaccination is a live-virus immunization containing vaccinia (not
variola) virus. Vaccinated individuals may shed live virus for 2-3 weeks, and
this shedding inadvertently can be passed to close contacts. Inadvertent
exposure to this live virus can be very serious for persons with compromised
immune systems or chronic diseases, and in pregnant women. This was much less
of an issue during the earlier era of vaccination. We did not have advanced
medical treatments that extended the lives of patients with cancer, human
immunodeficiency virus infection, or autoimmune disorders, nor did we
accomplish significant, successful organ or bone marrow transplantation. Also,
women were generally immunized as children -- well before childbearing age.
Vaccination:
Vaccination
administered within four days of first exposure has been shown to offer some
protection against acquiring the infection and significant protection against a
fatal outcome. An emergency vaccination program should include all health
workers at clinics or hospitals that may receive such patients and all disaster
workers such as EMS, hospital staff, police, public health staff, and mortuary
staff. These personnel should be vaccinated as soon as the first case is diagnosed,
irrespective of prior vaccination status. Vaccination should be considered for
any other persons who would be responsible for patient care during a suspected
outbreak of smallpox and for the investigation and control of suspected
outbreaks of smallpox.
Contraindications to
Smallpox vaccine
Some
important features of these efforts are:
Sharing of disease data – ODRS Ohio Disease Reporting
System - (electronic reporting
mechanism for Ohio Department of Health)

The
idea behind this pre-event vaccination program within the civilian community is
to produce a cadre of medical and emergency personnel who would be able to
investigate index cases of smallpox and care for smallpox victims while not
becoming casualties themselves.
Based on current ACIP (Advisory Committee on Immunization Practices)


CDC has released an updated version of the post-event Smallpox
Response Plan and Guidelines. This is the second revision to these
guidelines since they were released in November 2001.
Version 3 of the guidelines contains an important addition---the
"Smallpox Vaccination Clinic Guide." This guide provides the
operational and logistical considerations associated with implementing a
large-scale, voluntary vaccination program as part of a multifaceted response
to a confirmed smallpox outbreak.
Following a confirmed
smallpox outbreak within the United States, rapid, voluntary vaccination of a
large segment of the population might be required to
1) Supplement priority
surveillance and containment control strategies in areas with smallpox cases.
2) Reduce the at-risk
population for additional intentional releases of smallpox virus if the
probability of such occurrences is considered significant
3) Address heightened
public concerns about access to voluntary vaccination.
The most important component of smallpox containment is the rapid identification, isolation, and vaccination of close contacts of infected patients and contacts of their contacts (i.e., ring vaccination).
This strategy involves identification of infected persons through intensive surveillance, isolation of infected persons, vaccination of household contacts and other close contacts of infected persons (i.e., primary contacts), and vaccination of household and other potential contacts of the primary contacts (i.e., secondary contacts).
The clinic guide will assist planning for larger-scale, post-event
vaccination when exposure circumstances indicate the need to supplement the
ring vaccination approach with broader protective measures. The clinic guide
describes the activities and staffing needs associated with large-scale
smallpox vaccination clinics, including suggested protocols for vaccine safety monitoring and treatment. The clinic
guide provides an example of a model smallpox clinic and provides samples of
pertinent clinic consent forms and patient information sheets that would be
used at a clinic.
The clinic guide and the Smallpox Response Plan and Guidelines, Version 3 are available at http://www.cdc.gov/smallpox.
\

CDC will take additional steps to increase preparedness to respond
to a smallpox exposure of any magnitude, including updates to the Smallpox Response Plan and Guidelines.
Updates on infection control, in-hospital isolation recommendations, post-event
vaccination protocols, and outbreak response strategies are under way and will
be posted on the CDC website.
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From
the Methodist Medical Center, Dallas, Texas.
Pharmacotherapy
23(3):271-273, 2003. © 2003 Pharmacotherapy Publications