Condition Basics

What is Lyme disease?

Lyme disease is a bacterial infection spread by ticks. You can get Lyme disease if you're bitten by an infected tick. But most people who've had a tick bite don't get Lyme disease. If you don't treat Lyme disease, it can lead to problems with your skin, joints, heart, and nervous system.

What causes it?

Lyme disease is caused by a bacteria. Infected ticks spread the bacteria by biting people or animals.

Two types of ticks carry the Lyme disease bacteria in the U.S. They are:

Dogs, cats, and horses can become infected with Lyme disease bacteria, but they can't pass the illness to humans. But infected ticks may fall off the animals and then bite and infect humans.

Can you prevent it?

To help prevent Lyme disease, cover up as much skin as you can when you will be in wooded or grassy areas. Wear a hat, a long-sleeved shirt, and long pants with the legs tucked into your socks. Use a bug repellent with DEET that can keep away ticks.

What are the symptoms?

One sign of Lyme disease is a round, red rash that spreads at the site of a tick bite. This rash can get very large. Flu-like symptoms are also common. If Lyme disease goes untreated, you can develop swelling and pain in your joints, plus problems with your heart and nervous system.

How is it diagnosed?

Your doctor will ask questions about your symptoms and do a physical exam. The round, red rash is a sign of Lyme disease. Your doctor will also ask questions to find out if you've been around infected ticks. You may have a blood test to see if you have certain antibodies in your blood.

How is Lyme disease treated?

Lyme disease is treated with antibiotics. If Lyme disease goes untreated, it can lead to problems with your skin, joints, nervous system, and heart. The problems often get better with antibiotics. But in rare cases, they can be lifelong.