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PATHOLOGY PERSPECTIVES DEER TICK LIFE CYCLE Most ticks live about two years. Typically they hatch in spring, but a second hatching occurs in late summer. The tiny larvae stay close to the hatch site (often in leaf mold), hoping to latch onto a passing host, usually a bird or small mammal like a chipmunk or mouse. Any larvae that don't fi nd a host die. If this initial host is a carrier for any pathogens, the tick becomes an intermediate reservoir. After its fi rst blood meal, the larva drops off and molts into a small nymph that overwinters in woody, leafy areas. Nymphs become active again in spring, climbing up grass or bushes to seek out a new host. Humans are most likely to encounter them at this stage; the majority of tick bites are from nymphs and are reported between May and August. When the nymph has fi nished its meal (which can take fi ve days or more), it drops off the host and molts for several weeks to become an adult. At this stage the tick seeks a larger host, like a deer. Ticks may live and mate on this host for months. In the fall, the females fall off into leafy underbrush to lay thousands of eggs that will begin the cycle again the following spring. LYME DISEASE In 1974, the town of Old Lyme, Connecticut, saw a sudden spike in the incidence of what was assumed to be juvenile rheumatoid arthritis (JRA). Because JRA is not considered to be communicable, another cause for this sudden outbreak was postulated. A research team led by Willy Burgdorfer, PhD, investigated, and in 1982 they defi nitively identifi ed a spirochetal bacterium that lives in the midgut of deer ticks as the causative agent of these mysterious cases of childhood arthritis. Resources Burgdorfer, W. et al. 1982. Lyme disease—a tick-borne spirochetosis? Science 216, no. 4552:1317–19. Edlow, J.A. Tick-borne diseases, introduction. WebMD. www.emedicine. com/emerg/TOPIC584. HTM (accessed August 2008). bloodstream of the host. If this transfer is made, then symptoms develop, and complications may occur. SIGNS AND SYMPTOMS Early symptoms of Lyme disease generally appear 7–30 days after a tick bite. They include a circular red rash that clears in the center (a bull's eye rash, image 5) that is hot and itchy, but not raised from the skin. This is often called erythema migrans. Fever, fatigue, night sweats, headache, swollen lymph nodes, and neck ache may mimic fl u or mononucleosis. Later symptoms can include Lyme disease is an infection with Borrelia burgdorferi (image 4) that is transmitted through the bite of deer ticks. This is the most common tick- borne disease in the United States, infecting about 20,000 people each year. The vast majority of infections, about 90 percent, occur in 10 key states, including Connecticut, Delaware, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island, and Wisconsin. Lyme disease does occur outside these areas, however. It has been reported in 46 states and the District of Columbia, although in much lower numbers. When a person is bitten by a deer tick, the parasite typically feeds for several days before falling off (if it isn't discovered before that time). Not every tick bite results in infection; it is estimated that Lyme disease occurs in only 3–5 percent of all recognized tick bites. It can take several hours, or even a couple of days for the bacteria in the midgut of the tick to enter the irregular heartbeat and dizziness, confusion, facial paralysis, numbness, tingling, and poor coordination. Finally, the infection can cause extreme and painful infl ammation of one or more large joints: knees, elbows, and shoulders are most typically involved. Lyme disease is common, and its symptoms are easily mistaken for other conditions. People who live in areas with a high incidence and who develop symptoms of Bell's palsy or chronic fatigue syndrome are often routinely tested for Lyme disease. DIAGNOSIS AND TREATMENT The diagnostic procedure for Lyme disease begins a description of symptoms, followed by blood tests. These tests are sensitive and can give accurate information about exposure to B. burgdorferi, but they cannot determine whether symptoms are related to a current or visit massageandbodywork.com to access your digital magazine 109