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Lyme disease is the most commonly diagnosed tick-borne disease, both in Indiana and the nation. It was first recognized in the United States after a high incidence of arthritis was observed in children around Lyme, Connecticut in the mid 1970s.
Lyme disease has been identified in many states, but 90 percent of cases are reported from approximately 100 counties located along the northeastern and mid-Atlantic seaboard, from Massachusetts to Delaware, and in the upper north-central region of the U.S., including Wisconsin and parts of Minnesota.
Since 1990, there have been 280 Lyme disease cases reported from 70 counties in Indiana, 19 percent of which involved individuals less than 15 years of age. The age range for these Lyme disease cases is from 1 year to 89 years of age. Some Indiana residents were infected while traveling to high-risk states, but most were infected around their home, on the job, or at outdoor recreation sites around the state.
Lyme disease is normally transmitted in a cycle involving deer ticks, small mammals, and deer. Humans can be infected when a tick attaches itself to a person to take a blood meal. The tick must engorge blood on an individual host for approximately 48 hours before it can transmit Lyme disease.
Lyme disease is caused by the bacteria, Borrelia burgdorferi, which causes a flu-like acute disease as well as several chronic syndromes related to swollen painful joints, cardiovascular problems, or neurological problems like Bell’s palsy. Signs and symptoms of Lyme disease usually occur 7-14 days after exposure to an infective tick, but may occur as early as 3 days and as late as 30 days after the bite of an infective tick..
Early symptoms may include: fever, headache, fatigue, neck pain, stiffness in muscles and joints. About 60 percent of the time a rash called erythema migrans will develop at the site of the tick bite. This rash tends to enlarge over time and has ranged in size from 2.5 inches diameter to more than 14 inches in diameter.
If Lyme disease is not treated at this early stage and spreads, additional skin lesions may appear, as well as the systemic syndromes often referred to as late or chronic Lyme. The systemic syndromes can include arthritis of large joints, especially the knees. They can also include cardiovascular problems like atrioventricular blocks, which may require the insertion of a temporary pacemaker, or neurological illnesses like meningitis, encephalitis, or changes in cranial nerve functions (especially facial nerve paralysis). If untreated, these conditions may last for months or for years.
Diagnosis of Lyme disease is based on clinical findings in a patient who has recently been bitten by an infected tick. Human cases may be confirmed in the laboratory by identifying the organism, Borrelia burgdorferi, in culture or biopsy or with serological testing to identify antibodies against the organism.
The Centers for Disease Control and Prevention recommends a two-step testing method to serological testing to improve reliability. The first test is the enzyme-linked immunosorbent assay (ELISA) or enzyme immunoassay (EIA) test to detect either IgM and/or IgG antibodies, followed by the Western Blot test when ELIZA or EIA test is positive or equivocal.
Early Lyme disease responds to antimicrobials such as doxycycline, amoxicillin, or azithromycin when prescribed for two to three weeks. Treatment for late or chronic Lyme disease often requires the use of intravenous antimicrobials, usually ceftriaxone or penicillin, typically for two or three weeks. The prescribing of antibiotics to an individual with a history of a tick bite acquired in an endemic area, but who are not symptomatic is controversial.
While Ixodes scapularis, the deer tick, has been found in 59 Indiana counties, the risk for acquiring an infection appears to be quite low even in the counties where a high number of ticks have been identified. Indiana counties that are judged to have a moderate risk of exposure to Lyme disease are Jasper, Lake, LaPorte, Newton, Porter, Pulaski, Starke and Vigo. All other Indiana counties are considered to be low risk or minimal risk. To view the national risk map prepared by the Centers for Disease Control and Prevention (CDC), click here. [http://www.cdc.gov/ncidod/dvbid/lyme/riskmap.htm]
Prevention of Lyme disease is the same as for all other tick-borne disease. Avoid tick habitat, change yard environments to reduce tick populations, and use personal protective measures to prevent ticks from attaching to skin. For detailed information on tick-borne disease prevention, click here