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234 CHAPTER 11

organism of human Lyme disease but different causative
species that cause similar diseases have been discovered
on other continents. These spirochetal agents of human
disease are transmitted by members of the Ixodes com-
plex, which includes I. dammini in eastern North Amer-
ica and I. pacificus in western North America.

Symptoms of Lyme Disease

As previously listed, three distinct stages of Lyme disease
exist. During the first stage, called the localized phase,
symptoms and signs initially emerge. In approximately
80 percent of the cases the accompanying signs will even-
tually include a rash called erythema migrans at the site of
the tick bite. It is estimated that about 50 percent of those
who are infected with Lyme disease will rather quickly
develop a rash within 4 weeks following the bite by an
infective tick. This circular rash may grow progressively
larger over a period of time. However, some who have
contracted Lyme disease will have only mild symptoms
and signs or perhaps none at all. Victims clinically diag- Source: Centers for Disease Control and Prevention (CDC)
nosed with a Lyme disease infection may not even recall
receiving a tick bite or finding any ticks on themselves.
Those who live in endemic areas where Lyme dis-
ease occurs most frequently includes states along the
Atlantic coast, the Midwest, and more recently some
locations in Oregon and California. The circular or bull’s
eye rash appears especially during the warm months of FIGURE 11-9 Erythematous rash in bull’s-eye
pattern at the site of a tick bite
the year and is frequently the only sign of a very early
stage of Lyme disease (Figure 11-9). The disease pro-
gresses through three major stages: disseminated infection, will ensue if treatment has
■ Stage One not been initiated during the early stage and when
early symptoms first appeared. At this point the
Some who become infected with the causative
infection, which is multi-system in its attack, may
organism for Lyme disease will have flulike
symptoms that may include a rash but in a affect the skin, skeletal joints, heart, and the nervous
system within a relatively short period of a few weeks
considerable number of cases will not result in
such symptoms. Symptoms may even mimic to a few months. Subjective symptoms and clinical
signs at this point may include additional rashes
those of mononucleosis due to the swollen lymph
nodes and other well-known maladies early in the over the body other than the area where the initial
bite occurred. Considerable fatigue may be accom-
disease process. Most often there will be general
malaise and fatigue that may include a headache panied by pain, weakness, or numbness in the upper
and lower extremities due to the nervous system in-
and stiff neck, which might become confused with
meningitis. Fever and chills are somewhat common volvement, and may even include partial paralysis of
some facial nerves. Recurring headaches, problems
and in particular muscle and joint pain will appear.
with memory, and an inability to think clearly are
■ Stage Two further manifestations of disturbances of the central
After a month or more (sometimes up to 4 months) nervous system. Tachycardia (rapid heartbeat) may
following the initial infection, the second stage, early occur during this stage and in rare instances serious