Lyme Disease is an illness caused by a corkscrew-shaped spirochete bacterium (Borrelia burgdorferi) that is transmitted to humans, dogs, horses, and other animals by tick bites.
In 70-80% of infected individuals, a rash expanding from the tick bite and exceeding two inches in diameter will appear within a few days up to three weeks after the tick bite. As the rash expands it may develop paler bands, giving it a “target” appearance. Occasionally, similar satellite rashes may appear on other parts of the body. The initial symptoms of Lyme disease are fatigue, malaise, muscle aches and pains, headache, chills, fever. Untreated, additional symptoms may occur including hot swollen joints, paralysis of one side of the face (Bell’s palsy), shooting pains and dizziness caused by disturbances in cardiac rhythm. Most symptoms of Lyme disease respond to antibiotic treatment. Ten to 20% of treated Lyme disease patients may continue to have muscle and joint pains and fatigue that persist for weeks or months despite eradication of the spirochete. The cause of these symptoms is unknown, but may in part reflect an autoimmune response in which residual antibodies attack tissues. If Lyme disease is suspected, it is important to get treated early; antibiotic treatment is very effective and can prevent later, more serious complications.
Examples of rashes from tick bite:
Since first introduced in Maine in the 1980’s, vector deer ticks have become abundant in coastal counties and, with the exception of higher elevations, are now established throughout southern and central Maine. They are less abundant in northern counties where white-tailed deer, the primary host for mated female deer ticks, are sparse and temperatures are cooler. The distribution of Lyme disease cases across the state mirrors that of deer ticks that have been submitted to our lab for identification since 1989.
The greatest risk of humans contracting Lyme disease is during the seasonal peak of deer tick nymphs, which in Maine is reached in late June and July. Approximately two-thirds of Maine cases are reported in June, July and August. Because deer tick nymphs are tiny and their bite painless, they frequently go undetected beyond the ~36 hours they usually need after attaching to transmit the Lyme spirochete.
Adult deer ticks also transmit B. burdorferi during their season, which is in the late fall and early spring. Their size frequently leads to their being removed prior to the transmission of disease for humans; less likely on furred animals, hence adults are the primary transmitters of Lyme spirochetes to dogs and other domestic animals. With one extra opportunity to feed on an infected host, the prevalence of infection in questing adult ticks is generally twice that in nymphs. Male deer ticks, however, rarely feed and do not cause infection. Where deer ticks are firmly established in southern and mid-coastal counties, typically at least half the adults and one quarter of nymphs are infected. Infection prevalence, however, may vary sharply within a community.