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    "Ticks - Biology and their control"
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  • E-243-W
    "The Biology and Medical Importance of Ticks in Indiana"
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  • E-244-W
    "Lyme Disease"
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Lyme Disease

Lyme disease (LD) was first recognized as a new form of inflammatory arthritis near the town of Lyme, Connecticut in the mid-1970s. Since then, LD has been documented throughout the continental U.S. and now is the most common vector-borne disease in the U.S., with approximately 20,000 cases reported yearly to CDC. LD has been reported from more than 70 counties in Indiana. Readers are encouraged to consult Purdue Extension publication E-244-W "Lyme Disease" (PDF 834KB) in which general information on Lyme disease is presented. It also includes links to other Web sites that provide more in-depth coverage, including information pertaining to treatment of acute and chronic Lyme disease.

Causative agent

  • A bacterium, specifically a spirochete, with the scientific name Borrelia burgdorferi. Spirochetes are large, mobile bacteria that are capable of spreading into various parts of the body.

Geographical distribution of cases

  • The vast majority of LD cases are in southern New England , New York and the mid Atlantic states.
  • A second focus of LD cases is in the upper mid west, with most cases in Minnesota and Wisconsin.
  • The number of LD cases is increasing in Indiana , especially in northern counties.

Symptoms of infection

  • Initial symptoms are flu-like, usually with a characteristic reddish "bulls-eye" rash or erythema migrans lesion (EM lesion) at the site of inoculation (about 60-80% of patients).
  • Subsequent symptoms in patients can include secondary EM lesions (about 25%), neurological complications such as body pain, encephalitis, Bell's Palsy (10-20%), and irregular heartbeat (4-10%).
  • Chronic symptoms in patients can include arthritis, especially in knees, and neurological complications such as body pain, loss of motor skill, memory loss, sleep disorders, and chronic fatigue (about 60%).

Reservoir host of Borrelia burgdorferi

  • The white-footed mouse, Peromyscus leucopus.

Vectors of Borrelia burgdorferi

  • Nymphs of Ixodes scapularis, black-legged tick, in the eastern U.S., including Indiana.
  • Adults of Ixodes pacificus, the western black-legged tick, in Pacific Coast states.

Modes of transmission

  • From infected Ixodes scapularis nymphs to humans via their bite.
  • From infected Ixodes scapularis larvae to nymphs to adults via transstadial transmission.
  • From infected Ixodes scapularis females ticks to their eggs via transovariole transmission.
  • NOTE: there is no human-to-human transmission.

Diagnosis of infection

  • Symptoms, especially the EM lesion or secondary EM lesions, together with June-July onset in Indiana.
  • NOTE: laboratory tests to detect antibodies in patient's blood are of questionable value.

Treatment of infection

  • Antibiotic prescribed by a physician.
  • NOTE: antibiotics are effective during the acute infection, but less effective against chronic disease.

Prevention of infection

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