Lyme disease

Lyme disease is a bacterial infection that is spread to humans from the bite of the deer tick. Most Lyme disease in the northeastern United States occurs during summer or fall, when the small nymphal ticks are most prevalent.

The disease was first reported in the U.S. in 1977 in Old Lyme, Conn. The same disease occurs in many parts of Europe and Asia. In the U.S., most Lyme disease infections occur in the northeastern states, from Virginia to Maine; north-central states, mostly in Wisconsin and Minnesota; and west coast, mainly in the northwest.

Other names for Lyme disease include Borreliosis and Bannwarth syndrome.

Lyme disease is caused by bacteria called Borrelia burgdorferi (B burgdorferi). Blacklegged ticks, also called deer ticks, can carry these bacteria. Not all species of ticks can carry these bacteria.

Immature deer ticks, called nymphs, are the most common vectors for Lyme disease. They are about the size of a pinhead. Nymphs pick up bacteria when they feed on small rodents, such as mice, infected with B burgdorferi.

You can get Lyme disease only if you are bitten by an infected tick.

There are three stages of Lyme disease:

• Stage 1 is called early localized Lyme disease. The bacteria have not yet spread throughout the body.
• Stage 2 is called early disseminated Lyme disease. The bacteria have begun to spread throughout the body.
• Stage 3 is called late disseminated Lyme disease. The bacteria have spread to distant sites such as the joints and nerves.

Risk factors for Lyme disease include:

• Doing outside activities that increase tick exposure, including gardening, hunting, or hiking, in an area where Lyme disease occurs.
• Walking in high grasses in areas where Lyme-infected nymph ticks live.

Important facts about tick bites and Lyme disease

A deer tick must be attached to your body for 36 to 48 hours in order to spread the bacteria to your blood.

Nymphal deer ticks are the size of a poppy seed – so small that they are almost impossible to see. Many people with Lyme disease never even see or feel a tick on their body.

Most people who are bitten by a tick do not get Lyme disease.

The Centers for Disease Control and Prevention (CDC) continues to recommend a two-tiered approach to check for antibodies to the bacteria that cause Lyme disease.

Both tests are needed, but they can be done on the same tube of blood.

The most common first test is an enzyme-linked immunosorbent assay (ELISA) screen for antibodies against B burgdorferi. The second test can be an immunoblot or another, different ELISA.

If the first test is negative, either Lyme disease is not the diagnosis or it is too early for the body to have made detectable Lyme antibodies (fewer than 30 days after infection). A repeat test a few weeks later may be needed.

If the first test is positive or indeterminate, a second test is needed to confirm the diagnosis of Lyme disease.

Early in infection, your healthcare provider will usually make a diagnosis of Lyme disease based on your clinical signs and symptoms without doing any lab tests.

People bitten by a tick should monitor the attachment site closely for at least 30 days to see if a rash or develops, and be alert for flu-like symptoms, since 20 to 30 percent of Lyme disease patients do not recall ever having a rash.

A single dose of the antibiotic doxycycline (200 mg) may be given to someone soon after being bitten by a tick, when all of these conditions are true:

• The person has a deer tick that can carry Lyme disease attached to his or her body. This usually means that a nurse or doctor has looked at and identified the tick.
• The tick is thought to have been attached to the person for at least 36 hours.
• The person can start taking the antibiotic within 72 hours of removing the tick.
• The person is at least 8 years old and is not pregnant or breastfeeding.
• Local rate of ticks carrying B burgdorferi is 20 percent or higher.

A 10 to 14 day course of antibiotics is used to treat people who are diagnosed with early Lyme disease, with the duration depending on the choice of drug. The choice of antibiotic depends on the stage of the disease and the symptoms.

Common choices include doxycycline, amoxicillin, cefuroxime, and azithromycin.

Later stages of Lyme disease are also often treated with these same pill antibiotics for up to a month; intravenous ceftriaxone is sometimes needed for refractory arthritis or neurologic disease.

When treated early, antibiotics cure Lyme disease in more than 99 percent of cases. Without treatment, complications involving the joints, heart, and nervous system can occur. However, these symptoms are still treatable and curable.

Occasionally, a person keeps having symptoms that interfere with daily life after they have been treated with antibiotics; this is sometimes called post-Lyme disease syndrome.

Studies have not shown any lasting benefit of using long-term antibiotics after treatment for Lyme disease, and have also shown that most people feel back to baseline within a year without specific additional treatment.

Contact a healthcare provider if you have:

• A large, red, expanding rash that may look like a bull’s eye.
• Had a tick bite and develop fever, chills, sweats within days to weeks.

There are ways to help prevent Lyme disease, including taking the following precautions to avoid tick bites:

• Be extra careful during warmer months.
• When possible, avoid areas with high grass.

If you do walk or hike in these areas, take measures to prevent tick bites:

• Wear light-colored clothing so that if ticks land on you, they can be spotted and removed.
• Wear long sleeves and long pants with pant legs tucked into your socks.
• Spray exposed skin and your clothing with insect repellant, such as DEET for your skin or permethrin for your clothes. Follow the instructions on the container.
• After returning home, remove your clothes and thoroughly inspect all skin surface areas, including your scalp. Shower as soon as possible to wash off any unseen ticks.

How to remove a tick that is attached to your skin

If a tick is attached to you, follow these steps to remove it:

• Grasp the tick close to its head or mouth with tweezers. DO NOT use your bare fingers. If needed, use a tissue or paper towel.
• Pull it straight out with a slow and steady motion. Avoid squeezing or crushing the tick. If parts of the body remain in your skin do not try to fish them out – they will not transmit Lyme and you can cause a skin infection.
• Clean the area thoroughly with soap and water. Also, wash your hands thoroughly.
• Save the tick in a jar or take a good, clear photo to show your healthcare provider if you become sick.
• Watch the site carefully for the next several weeks for signs of Lyme disease.