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- One very important attribute
of Lyme disease infection
is that without treatment, it will become
a chronic persistent infection
in the majority of people.
This means if people
aren't diagnosed accurately
and have misdiagnosis,
the majority of people will
go on to chronic infection
and chronic symptoms.
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A more complicated aspect of Lyme disease
is what occurs in some
people even with treatment.
Some patients with Lyme
disease will continue
to experience chronic symptoms
and signs of Lyme disease.
The best documented
episodes of this happening
are in patients with Lyme arthritis.
The majority of people
respond to antibiotic therapy,
but clearly, a subset of
people with Lyme arthritis,
even with appropriate antibiotic therapy,
go on to develop chronic
problems with their knee,
chronic pain, chronic knee
swelling that doesn't go away
even with aggressive antibiotic therapy.
Other stages of Lyme disease may also have
chronic symptoms after treatment.
This can even occur when
patients are treated early
in Lyme disease with their
acute rash and symptoms.
And there's many theories about why people
develop persistent symptoms
even after antibiotic therapy.
And this is one of the
key parts of the research
at the Johns Hopkins Lyme
disease Research Center
is understanding the mechanism
of persistent symptoms
in both people that have not been treated,
but especially in people
that have been treated
but remain ill.
Understanding those
persistent symptoms in people
that were treated is a huge
mission of our research center.
We can't understand effective therapy
of people with persistent symptoms
until we understand the mechanism,
what's driving the persistent symptoms.
Are the mechanisms
related to the bacteria?
Are the mechanisms related
to the human immune response
to the bacteria?
Or is it a combination of things
that drives these persistent symptoms
in the patients we see?
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Lyme disease is a multi-system infection.
It starts in the skin at
the site of a tick bite.
But it rapidly leaves the
skin, enters the bloodstream
and the lymphatic system and spreads to
other areas of the body.
The Lyme disease bacteria
loves certain types of tissues
when it spreads.
One of the major tissues that
the Lyme disease bacteria
spreads to are the joints.
Another area that the Lyme
bacteria likes to go to
is the heart, and this is one area
that can cause
relatively rapid
symptoms
and sometimes even
fatal symptoms.
When the bacteria affect the
heart's electrical system,
it can cause what's called heart block
or extreme slowing of the heart rhythm.
When the slowing is extreme,
it can actually proceed
to a loss of consciousness
and sometimes death.
And this Lyme carditis can
progress without treatment
and it is a rare but important cause
of death in Lyme disease.
A favored site that the bacteria goes to
is the neurologic system.
The Lyme bacteria can cause meningitis
in the first month of infection.
The Lyme bacteria also can go to
nerves and some of the favored nerves
that Lyme disease involves
are what are called
cranial nerves; people develop
what is called Bell's palsy
or a droopy face.
The majority of nervous system involvement
with Lyme disease causes
painful nerve dysfunction
and this common nerve dysfunction
is a product of the Lyme disease
going to the nervous system
where the nerves typically
are involved in sensation
and pain transmission.
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The biggest risk factor
for persistent symptoms
of Lyme disease is failure to make
an early and accurate diagnosis
and a failure to initiate
adequate treatment.
And that, again, emphasizes
why it's so important
to make the accurate, acute
diagnosis of Lyme disease
to reduce the risk of people
having these persistent symptoms.
Another risk factor
for persistent symptoms
in Lyme disease seems to
be neurologic involvement.
A major area of our research is looking at
neurologic involvement in
patients with persistent symptoms
in Lyme disease.
One intriguing discovery
we've made is that
people's cognitive function
in persistent Lyme disease
is not normal; patients
often tell us that they have
difficulty with memory,
with multi-tasking,
and we've found that, in fact,
that is true on detailed
neuro-cognitive testing,
patients that have persistent symptoms
often have decrements in
their cognitive testing.
A fascinating discovery we're making
is a correlation in
these cognitive deficits
with actual imaging of the brains
using sophisticated techniques
of functional MRI scanning
and
white matter scanning in the MRI.
These early findings
suggest that there may be
a connection between
the cognitive symptoms
patients report
and the actual changes on brain
anatomy using
highly sensitive
MRI scanning.
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The immune system is
critical in the interaction
of the Lyme bacteria with our body
and the immune system
is the crucial aspect
of how we fight Lyme disease.
Not all people's immune
systems are the same
and one of the important
genetic aspects of Lyme disease
probably has to do with genetic variation
in our immune system.
Some people's immune systems may not be
genetically programmed in an ideal way
to fight Lyme disease,
and other people's immune
systems may be stronger
in their way that they respond
to the Lyme disease bacteria.
This variation in genetics
and the genetic control
of the immune system is
likely an important part
of understanding why some people recover
from Lyme disease and others
develop these persistent
symptoms even after treatment.
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Lyme disease can also
be complicated by other
diseases and infections.
People come into Lyme
disease with their own
unique health history
and certainly people's
underlying health history can impact
their manifestations and
response to treatment
in Lyme disease.
And Lyme disease can also
occur as what's called
a co-infection with other
tick-borne infections.
Unfortunately, the deer
ticks that transmit
Lyme disease in North America
can also carry other tick-borne infections
and importantly, if
somebody gets more than one
tick-borne infection
from a single tick bite,
that can create a more severe
and complicated infection.
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