Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted to people by the bite of infected ticks (Ixodes scapularis or Ixodes pacificus).
What is Lyme disease and how is it transmitted?
Caused by the Borrelia burgdorferi bacterium, Lyme disease is transmitted by the bite of certain species of ticks. The bacterium, normally found in mice, squirrels and other small mammals, does not harm these animals—or the deer the ticks feed on—but causes potentially serious disease when transmitted to people. In the Northeast United States, the Lyme disease vector is the black-legged or deer tick (Ixodes scapularis); in Pacific coastal United States, the western black-legged tick (Ixodes pacificus) transmits the disease. Most cases occur in the early spring and summer when the ticks are in the nymph stage, and people are most likely to be outdoors. Nymph-stage ticks are difficult to see with the naked eye.
The first symptom of Lyme disease appears 3 to 30 days after the tick bite: a circular rash (erythema migrans) around the site the bite. It develops into a characteristic “bull’s eye” with a clear center that can be up to 12 inches in diameter. Patients also experience painful lymph node swelling, joint pain (arthralgia), chills, fever, headache, muscle aches (myalgia) and other non-specific symptoms. Left untreated, the infection can lead to more serious symptoms such as drooping of the face (Bell’s palsy), heart palpitations, dizziness, severe headaches and joint pain. After several months, approximately half of all patients with untreated Lyme disease develop arthritis in large joints as well as chronic neurological problems, including cognitive difficulties.
“bull’s-eye” rash typical of Lyme disease
State health departments reported 28,921 confirmed cases and 6,277 probable cases of Lyme disease to CDC in 2008. This represents a 5% increase in confirmed cases compared to 2007. The definition and reporting of probable cases was initiated in 2008 based on revisions to the national surveillance case definition.
How is Lyme disease treated?
Most cases can be treated effectively with antibiotics if treatment begins early. However, a small percentage of those infected and treated continue to experience symptoms such as muscle and joint pain, neurological difficulties and fatigue—likely due to autoimmune disorders triggered by the infection.
Is there a vaccine for Lyme disease?
Twenty years ago, there was a viable vaccine on the market to prevent Lyme disease in humans, and now there is not. To learn why, see our video interview with The New Yorker magazine writer Sue Hapern. Her article titled, “Why It Took So Long to Develop a New Vaccine for Lyme Disease” appeared in the August 2021 issue of The New Yorker.
How can I protect myself from Lyme disease?
You should take measures to prevent tick bites, particularly if you are planning on being in wooded areas where the carrier ticks are common. Insect Shield® Repellent Apparel is effective in repelling ticks, including the kind that can carry Lyme disease. We especially recommend Insect Shield socks and pants for tick protection, but other items of Insect Shield clothing can also prove helpful in thickly wooded areas.