What is Lyme disease?

Lyme disease is an infection caused by a spiral-shaped bacterium . It's most commonly spread by a tick bite. The disease takes its name from Lyme, CT. This is where the illness was first identified in the U.S. in 1975.

Lyme disease is a year-round problem in many parts of the U.S. and elsewhere. But April through October is generally the most active tick season. Cases of Lyme disease have been reported in nearly all states in the U.S. and in large areas in Europe and Asia. But the most common areas are the Northeast, upper Midwest, and northwestern states.

What causes Lyme disease?

Lyme disease is caused by bacteria that is spread to humans by tick bites. The ticks that carry the bacteria are:

• Black-legged deer tick (northeastern, mid-Atlantic, and North Central U.S.)

• Western black-legged tick (Pacific coastal U.S.)

Ticks prefer to live in wooded areas, low-growing grasslands, and yards. Not all ticks carry the Lyme disease bacteria. Depending on the location, anywhere from less than 1 in 100 to more than half of the ticks are infected with it.

While most tick bites are harmless, several species can cause life-threatening diseases. Tick-borne diseases include:

• Rocky Mountain spotted fever

• Lyme disease

• Anaplasmosis

• Babesiosis

• Colorado tick fever

• Powassan encephalitis

• Tularemia

• Ehrlichiosis

• Relapsing fever

Who is at risk for Lyme disease?

Factors that can raise your risk for getting Lyme disease include:

• Working or spending time outdoors in grassy areas where tick are found

• Having pets that can bring the ticks into the home

What are the symptoms of Lyme disease?

Many people infected with the Lyme bacteria will never have symptoms. Their bodies will cure the infection without needing any treatment. If the infection causes symptoms, the following are the most common ones that people have. They vary based on how long the person has had the infection.

The most common early symptom is a red rash that:

• Can appear several days after infection, or not at all

• Can last up to several weeks

• Can be very small or grow very large (up to 12 inches across), and may look like a "bullseye"

• Can mimic skin problems such as hives, eczema, sunburn, poison ivy, and flea bites

• Can itch or feel hot, or may not be felt at all

• Can disappear and return several weeks later

Several days or weeks after a bite from an infected tick, you may get the rash again. When the rash returns, it often affects many parts of the body. You may also have flu-like symptoms, such as:

• Headache

• Stiff neck

• Aches and pains in muscles and joints

• Low-grade fever and chills

• Tiredness (fatigue)

• Poor appetite

• Swollen glands

Weeks to months after the bite, you may develop:

• Nervous system symptoms, including inflammation (meningitis) and weakness and paralysis of a facial nerve (Bell palsy)

• Heart problems, including inflammation of the heart (myopericarditis) and problems with heart rate 

• Eye problems, including inflammation (for example, red eye)

Months to a few years after a bite, you may have:

• Inflammation of the joints (arthritis)

• Nervous system symptoms, such as numbness in the arms or legs, tingling and pain, and trouble with speech, memory, and concentration

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How is Lyme disease diagnosed?

Sometimes diagnosing Lyme disease can be hard. The symptoms may seem like other health problems. It may also not be known if the person was exposed to ticks.

Diagnosis is usually based on symptoms, particularly the typical rash of Lyme disease, along with a history of a known or possible tick bite. At the time of the first rash, blood testing is still negative and not helpful. For later symptoms, blood testing is done to confirm the diagnosis and rule out other conditions. If you have nervous system symptoms or joint swelling, your healthcare provider may test spinal or joint fluid for Lyme antibodies or the bacteria.

The symptoms of Lyme disease may look like other health problems. And other problems can be mistakenly diagnosed as Lyme disease. Always talk with your healthcare provider for a correct diagnosis.

How is Lyme disease treated?

Treatment will depend on whether the infection is active. If it's active, then treatment depends on what stage it is at and how severe it is.

Lyme disease in the earliest stage is treated with antibiotics for 2 to 3 weeks. Later stages may need up to 4 to 8 weeks of antibiotics. Doxycycline is the most common antibiotic used. In some cases, you may need to take amoxicillin, cefuroxime, or ceftriaxone.

Treatment will also be considered based on these and other factors:

• If you are bitten by a tick and have any of the symptoms

• If you are bitten by a tick and are pregnant

• If you are bitten by a tick and live in a high-risk area

• What kind of tick you are bitten by

• If the tick has taken a blood meal (engorged)

• How long the tick has likely been on your body

What are possible complications of Lyme disease?

Lyme disease affects people differently. Many people with Lyme disease are diagnosed early and cured by their first treatment. Relapse and incomplete treatment are unusual. But you can be reinfected after treatment if you are bitten by another tick. This is by far the most common reason for repeated infection.

Even untreated, most people with the infection will cure it on their own and never develop complications. Untreated, complications that can occur later may include:

• Joint infection, usually involving a single large joint, such as the knee

• Nervous system disease, including meningitis and encephalitis

• Heart inflammation (myopericarditis)

Rarely, these complications can result in chronic, debilitating conditions.

Some people may develop post-Lyme disease syndrome (PLDS). It may cause lasting musculoskeletal and peripheral nerve pain, fatigue, and memory problems without an active infection. Taking more rounds of antibiotics doesn't help.

Can Lyme disease be prevented?

People aren't able to become immune to Lyme disease. So even if you've had Lyme disease, you can get it again. No vaccine currently is available to prevent the disease in humans.

To help prevent Lyme disease, follow these guidelines.

When should I call my healthcare provider?

If your symptoms get worse or you have new symptoms, let your healthcare provider know.

Key points about Lyme disease

• Lyme disease is an infection caused by bacteria..

• Many people infected with the Lyme bacteria will never have symptoms and may cure it on their own without treatment.

• Lyme disease, if symptomatic, usually starts with a rash that's often described as a "bullseye."

• Lyme disease is generally easy to diagnose based on symptoms and a history of a tick bite or exposure. Blood tests may also be used, and rarely, spinal fluid or joint fluid may be tested.

• Lyme disease in the earliest stage is usually treated with antibiotics for 2 to 3 weeks. Some people develop complications if the infection is not found early.

• People aren't able to become immune to Lyme disease. You can get it again if you get another tick bite.

• Preventing tick bites is the best prevention for Lyme disease. If a tick is found on your body in the first 72 hours, your healthcare provider may give you a preventive antibiotic.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.