What is a tick?
Some basic information:
What is Lyme disease?
Lyme disease is an infection transmitted by the bite of certain, very small, infected ticks. Lyme disease gets its name from the town of Lyme, Connecticut, where the illness was first identified in the United States in 1975. The deer (or black-legged) tick, and the related western black-legged tick, are the primary known transmitters of Lyme disease in the United States. Both are hard-bodied ticks with a two-year life cycle.
What is the infectious agent that causes Lyme disease?
Lyme disease is caused by a corkscrew-shaped bacterium, or spirochete, called Borrelia burgdorferi. Ticks infected with the bacterium spread the disease to humans.
Who gets Lyme disease?
Cases of Lyme disease have been reported by nearly every state in the United States, but the disease is concentrated in the east coastal states, the north central states, and northern California. Connecticut, Rhode Island, New York, New Jersey, Delaware, Pennsylvania, Maryland, and Wisconsin account for about 90% of all cases.
In the Northeast and Great Lakes region, Lyme disease is spread by the black-legged tick, which lives in wooded areas, grasslands, and yards. In the Pacific Northwest, the disease is spread by the western black-legged tick. In the Southeast, the disease is thought to be spread by the black-legged tick. People who work or play outside or in wooded areas (park rangers, construction workers, campers, hikers, fishermen, hunters, golfers, gardeners) and anyone who loves the outdoors are at risk.
How do people get Lyme disease?
Ticks become infected with the Lyme disease bacterium by feeding on infected animals, such as mice, chipmunks, and other wild rodents. Lyme disease is passed to humans and other animals when a tick infected with the bacterium bites the person or animal and stays attached long enough (usually more than 36 hours) to take a blood meal.
The tick that spreads Lyme disease has a 2-year life cycle, and feeds once in each of its three life stages -- larvae, nymph, and adult. In the tick's larvae stage, it is tan, the size of a pinhead, and feeds on small animals like mice. During the nymph stage, the tick is the size of a poppy seed, beige or partially transparent, and feeds on larger animals such as cats, dogs, and humans. Adult ticks are black and/or reddish and feed on large mammals such as deer, dogs, and humans.
What are the signs and symptoms of Lyme disease?
The early stage of Lyme disease is usually marked by one or more of these signs and symptoms:
The skin rash is a red circular patch about 2 inches in diameter that appears and expands around the site of the tick bite. The center may clear as it enlarges, resulting in a "bulls-eye" appearance. The rash may be warm, but it usually is not painful or itchy.
Some infected people do not recognize the early symptoms and are diagnosed only after complications occur.
What complications can result from Lyme disease?
Persons who did not have or did not recognize the early symptoms and who did not receive treatment can end up with serious complications:
How soon after exposure do symptoms appear?
Early symptoms can develop within a week to a few weeks of the tick bite. Other symptoms can appear weeks, months, or years later.
How is Lyme disease diagnosed?
Lyme disease is diagnosed by a physical examination and medical history. The clinical diagnosis is supported by laboratory testing.
Diagnosis of Lyme disease can be difficult. Current tests are not completely accurate, and the symptoms can mimic those of other diseases. Diagnosis is easiest when there is a skin rash.
Who is at risk for Lyme disease?
Lyme disease can affect anyone. Persons who spend time in brushy and wooded areas are at increased risk of exposure. The chances of being bitten by a tick are greatest during times of the year when ticks are most active. Deer ticks in the nymph stage are active from mid-May to mid-August. Adult ticks are most active in mid- to late fall and early spring.
What is the treatment for Lyme disease?
Lyme disease is treatable with antibiotics taken for 3 to 4 weeks. More difficult cases may require longer treatment and combinations of drugs. Re-infection from tick bites is possible after treatment.
How common is Lyme disease?
Lyme disease is the most common disease spread by ticks in the United States. More than 16,000 cases were reported by 45 states in 1996. However, because of considerable under-reporting and misdiagnosis, the actual number of cases is probably several times higher.
Is Lyme disease an emerging infectious disease?
Yes. Lyme disease is a rapidly emerging infectious disease. Since it was first recognized in the United States in 1975, reports of Lyme disease have increased substantially, and the disease is now found in several regions of the country. Factors contributing to the rise in Lyme disease in humans is a thriving tick population and the expansion of suburbs into formerly wooded areas, which increases people's exposure to infected ticks.
How can Lyme disease be prevented?
A Lyme disease vaccine was developed and used for a short time but this has been pulled from the market. The only sure way to prevent the disease is to avoid exposure to infected ticks. Especially avoid areas where wild mice might live, such as the edges of yards, fields, and woods with low, dense ground-cover.
If this is not possible, you can reduce your risk by taking these precautions:
The information on the page is NOT meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about tick bites or Lyme disease, please consult a health-care provider.