Pre-Event
Planning
Pre-Event
Training
The
first step to establishing surveillance for smallpox is in training
health care providers and public health staff on the disease itself,
how to efficiently diagnose and differentiate the disease, and
the laboratory testing used to confirm it. Pre-event training should
include:
- Clinical
case definition.
- Differential
diagnosis of febrile vesicular pustular rash illness.
- High level
of alertness for cases of smallpox.
- Laboratory
diagnostic issues (VZV, others).
- Notification
procedures.
- Post-event
surveillance methods (Case search and Contact Tracing).
Public health
authorities should have systems and protocols in place to interview
the case and manage their contacts and the contacts of contacts
through a series of interviews and follow-up activities. Preparations
for the following should be completed during pre-event training.
- Case interview.
- Contact identification.
- Contact households,
other sites, travel modes.
- Contact risk
category for prioritization.
- Assignment
of contacts to tracing teams.
- Contact and
contact household member interviews.
- Vaccination
of contact and household members.
- Contact surveillance
for fever/rash follow-up.
- Reporting
of contacts with fever and rash for isolation.
- Vaccine take
and severe adverse event surveillance.
- Reporting
of severe adverse vaccination events.
- Maintaining
forms and data files.
- Data reporting.
Pre-Event
Smallpox Surveillance Clinical Case Definition
The following
is the clinical case definition for smallpox during a pre-event
period. This definition is slightly more broad than the standard
case definition in the hopes that it will be more sensitive in
catching a first case.
VARIOLA
DEFINITION:
An illness with acute onset of fever > 101¾F followed by a rash
characterized by firm, deep-seated vesicles or pustules in the
same stage of development without other apparent cause. Since
varicella (chickenpox) is the illness most commonly confused with
smallpox, it is important to learn this definition, as well. Remember
that the smallpox rash will have a different appearance and feel
than varicella.
VARICELLA
DEFINITION:
An illness with acute onset of diffuse (generalized) maculopapulovesicular
rash without other apparent cause.

Since it’s
the disease most often confused for smallpox, it will be important
to understand the epidemiology of varicella in order to determine
the likelihood of a rash illness being smallpox. In the United
States, the comparison was found to break down in interesting ways.
Both diseases
(at least when smallpox was naturally occurring) are most commonly
seen in the spring. While smallpox age ranges can be in any group,
current varicella epidemiology finds them mostly in children, with
only a small percentage of cases occurring in adults. With smallpox,
we consider the entire population to be susceptible. However, previous
immunity might remain among adults who were previously vaccinated.
Although rapidly changing after the introduction of varicella vaccine,
the most cases still occur among young children, with very few
adults susceptible, except for adults in tropical countries. Both
diseases are more severe at the extremes of age and among the immunocompromised,
yet smallpox causes ten times more fatalities. For all those fatalities,
however, varicella is much more infectious. Smallpox vaccine is
no longer routinely recommended, whereas a relatively new varicella
vaccine is rapidly gaining acceptance and changing the epidemiology
of the disease.
Because very
few healthcare providers currently working have experience with
smallpox and the early symptoms are indicative of so many other
diseases, we know we will miss the first few cases. However, the
pursuit of false positives can cost public health a lot in both
personnel and funding when, at this time, we know that many of
the rashes we’ll see are more likely to be caused by varicella,
disseminated herpes zoster or enteroviral infections. If after
going through the rash illness algorithm, a case is considered
to be suspect smallpox, it will mean a public health emergency.
Laboratory testing should be obtained immediately so that the appropriate
interventions can begin.
Public health
authorities also need to prepare their surveillance by ensuring
that there is someone dedicated to coordinating all surveillance
activities and that there are several different mechanisms that
are in place for reporting cases; such as standard physician reporting,
as well as laboratory reporting. This may or may not be possible,
but where it can be established, redundant mechanisms can help
to capture suspicion as early as possible.
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