The
first symptom of Lyme disease in humans is usually an expanding
red rash at
the site of the tick bite, which may occur within a few days or several
weeks later. The rash may be preceded or accompanied by flu-like
symptoms such as fever, headache, chills, nausea, facial paralysis,
or pain in the muscles and joints. If Lyme disease is suspected,
call your doctor immediately. Early antibiotic treatment is
very effective and can prevent later, more serious complications. Not
all patients develop the rash, however, and many do not recall a
tick bite.
In animals the
rash apparently does not occur. Lameness, loss of appetite, fever,
and lethargy may be the first indications. Animals usually respond
to prompt antibiotic therapy. Consult your veterinarian.
Over 800
cases of Maine-acquired Lyme disease have now been officially recognized.
The tick that transmits Lyme disease is the deer tick Ixodes scapularis (previously I.
dammini). This tick is well established in coastal areas, particularly
in York, Cumberland, and Knox Counties. Increasing numbers are being
found in inland areas often along rivers. Ticks are routinely found
in Androscoggin, Sagadahoc, Kennebec, Lincoln, Waldo, Hancock, and
Penobscot Counties. Dear ticks are occasionally found in other areas
of Maine; they are carried by some species of birds. Map
of tick distribution in Maine.
For completion
of its two-year
life cycle, each consecutive stage of the deer tick -- larva, nymph,
and adult --must take one blood meal. The tiny larvae active
from June to September, are seldom found, and become infected when
they take their first blood meal from a mouse or other small mammal. The
risk of humans contracting Lyme disease is greatest from the bite of
the inconspicuous nymphs which are most active in June
and July. Adult ticks, which can also transmit
Lyme disease, are found most often in the late fall as they search
for larger hosts, primarily deer. Those that are unsuccessful
may overwinter, to reappear in early spring or even during periods
of mild winter weather. The larger reddish females can also transmit
the Lyme bacteria, but the smaller, black males do not attach long
enough to do so.
The seasonal
appearances of the larval, nymphal and adult stages of the deer tick
in Maine are shown in a bar graph developed
from ticks submitted for identification over the last fifteen years.
Not
all deer ticks contain the spirochete. Limited studies
in Maine have shown that although in one site more than half the
adult ticks sampled were infected, infection rates may vary considerably,
even between adjacent areas at the same location.
Twelve
other species of ticks are found in Maine.
Other
tick borne pathogens. The organisms that cause two other
tick-transmitted diseases, human granulocytic ehrlichiosis (HGE)
and babesiosis, have been found in Maine. There have been several
locally-acquired cases of each confirmed in Maine residents during
the last few years. These infections may start with headaches,
fever, and other flu-like symptoms, but without the characteristic
rash of Lyme disease. HGE may cause severe illness, but responds
well to doxycycline and a few other antibiotics. Babesiosis is
an infection that invades red blood cells. It is most common
in older individuals or those with immune deficiencies (i.e.
without a spleen, etc.) and may cause persistent fever, anemia
or other blood abnormalities. HGE may also affect dogs and horses.
Powassan virus has also been found in Maine and to date has resulted
in four human cases. Powassan virus has been isolated from Ixodes
cookei, "the
woodchuck tick",
which is thought to be the primary vector.
