CCMS Medicine Winter 2017 - 25

headaches, and be incorrectly diagnosed as
having a viral illness.
In late stage neurologic Lyme disease,
one of the more common manifestations
is a mild to moderate encephalopathy,
with non-specific symptoms of memory
problems and fatigue, but the physician
may not consider Lyme disease in the
differential diagnosis because he or she
mistakenly relies too heavily on the
CDC surveillance criteria. Even if this
patient is shown to have a positive blood
test for Lyme disease, the physician may
mistakenly dismiss it as insignificant
because the clinical manifestations
fall outside of the CDC's surveillance
definition. The CDC recognizes that there
are clinical manifestations of Lyme disease
that fall outside of the narrow criteria
used for the case definition. This should
not be considered as an error by the CDC
but rather as an error by physicians who
misapply the CDC surveillance criteria,
inappropriately using these narrow criteria
developed for epidemiologic surveillance to
exclude clinical cases that do not meet the
strict "surveillance case definition."
The CDC recognizes that the
surveillance criteria should not be used
to exclude the clinical diagnosis of
Lyme disease; the narrow surveillance
criteria are not comprehensive enough
to encompass all manifestations of this
illness. Unfortunately, this surveillance case
definition has caused some confusion and
controversy among physicians and patients
regarding who should be diagnosed with
and treated for Lyme disease.
Physicians who rely too heavily on the
narrow CDC surveillance clinical criteria
might fail to correctly diagnose Lymeinfected patients who present with less
typical manifestations. In this situation
the treatment may be delayed or absent
altogether, resulting in unnecessary pain
and disability. If detected and treated
shortly after initial infection, Lyme
disease is often cured with a brief course
of antibiotics; however, delay in initiating
antibiotic treatment is problematic. When
treatment is delayed, the symptoms that
develop may be less responsive to standard
courses of treatment. Some patients
present with arthritis or a neuropsychiatric
illness as a complication of a previously
undiagnosed Lyme infection.

Over-diagnosis vs Under-diagnosis

Broader Symptom Spectrum for Lyme
With an awareness that the narrow
CDC criteria are appropriate for national
surveillance but not appropriate as the
sole basis for clinical decision-making
in individual cases, some physicians use
a broader, more inclusive set of clinical
criteria for the diagnosis of Lyme disease.
This group of doctors, after conducting
a careful history of tick exposure from
Lyme endemic areas, examining blood test
results, and ruling out other possible causes
of the patient's symptoms, may diagnose
the patient as having "probable Lyme
disease." Probable Lyme disease indicates
that the physician's diagnosis is tentative
but there is sufficient evidence to support
the possibility of Lyme disease as the cause
for the patient's multiple symptoms. In
this case, the physician explains that the
diagnosis is not definitive and reviews the
potential benefits and risks of treatment
with the patient. These physicians
recognize that Lyme disease can present
in a variety of ways and will treat patients
whose symptoms may not fit the narrower
CDC surveillance guidelines.
While recognizing that there are
significant risks associated with antibiotic
treatment, particularly when administered
intravenously, these physicians would
argue that the threat of serious physical,
cognitive, and functional problems
associated with long-term untreated Lyme
infection outweighs the risks of antibiotic
therapy. However, by taking this broader,
more inclusive approach to diagnosis
and treatment, it is likely that these
physicians will also treat some patients
with antibiotics who do not have Lyme
disease. When a patient diagnosed with
"probable Lyme disease" fails to improve
after antibiotic treatment, the diagnosis
should be reconsidered. An unwavering
focus by the physician (or patient) on Lyme
disease as the diagnostic explanation for
ongoing symptoms - even in the absence
of improvement with antibiotics - can be
harmful as other causes of the patient's
ongoing symptoms may be ignored.

Is Lyme disease under-diagnosed or
over-diagnosed? Both are occurring.
When doctors fail to apply good clinical
judgment in the interpretation of highly
suggestive serologic tests (e.g., 4 bands on
the IgG Western blot) in a patient with
high probability of Lyme disease - or
when they fail to consider the possibility
of new onset Lyme disease in a patient
from a Lyme endemic area who presents
with prolonged flu-like symptoms during
spring or early summer months without
having noticed a tick bite or rash - it
is likely that this doctor would risk not
treating someone who may well have Lyme
disease. Some patients may not develop
multiple CDC-specific bands until months
after the infection, and in rare cases, not
at all (the bacteria may evade the immune
system, or the antibodies may be bound
in immune complexes). Conversely,
when doctors fail to apply good clinical
judgment in the interpretation of weakly
positive serologic tests in a patient with a
set of symptoms not linked to Lyme (e.g.,
gastric distress, rhinitis) or with suggestive
but extremely common symptoms with
a broad differential diagnosis that has not
been fully evaluated or treated (e.g., fatigue,
depression, memory problems), then this
would likely be a situation of mis-diagnosis
of Lyme disease. Over-diagnosis might also
be seen if a patient is given a diagnosis of
Lyme disease who has had no known tick
bites or EM rash and no known exposure
to Lyme endemic areas but presents with
typical Lyme symptoms that occur in
other diseases (e.g., arthralgias, numbness/
tingling, diffuse pain) or with weakly
positive tests (e.g., a single positive IgM
Western blot or ELISA). Misdiagnosis is
a problem - whether it is over-diagnosis
or under-diagnosis - as in each case the
consequences can be serious.
It is important to keep in mind that
Lyme antibody tests obtained within the
first few weeks after the bite are often
negative, because it may take several weeks
before the antibodies become detectable on
blood tests.
Subsequent articles will address diagnostic
and treatment challenges, post-treatment
Lyme symptoms, aka "Chronic Lyme
Disease," and co-infections.

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Table of Contents for the Digital Edition of CCMS Medicine Winter 2017

CCMS Medicine Winter 2017 - 1
CCMS Medicine Winter 2017 - 2
CCMS Medicine Winter 2017 - 3
CCMS Medicine Winter 2017 - 4
CCMS Medicine Winter 2017 - 5
CCMS Medicine Winter 2017 - 6
CCMS Medicine Winter 2017 - 7
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CCMS Medicine Winter 2017 - 9
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