Lyme disease

Photo of a doctor removing a tick (PantherMedia / Alexander Raths)

Some ticks carry Lyme disease, which can be transferred to humans when they bite. This bacterial infection can be prevented if the tick is removed in time. Lyme disease is usually treated with antibiotics. If the infection is left untreated, complications can arise. But that is rare.

Lyme disease is an infectious disease caused by bacteria. It is more common than tick-borne encephalitis (TBE), another disease that can be transmitted by ticks. In Germany, about 3 out of 10,000 people develop Lyme disease each year.

How can you tell if you have Lyme disease?

If you are infected with Lyme disease, the skin near the bite becomes inflamed. The bacteria that cause the infection – called Borrelia bacteria – might later go on to attack joints or various organs, but Lyme disease usually doesn't cause any serious problems.

It is normal for the skin around a tick bite to turn red and itch. This inflammatory reaction has nothing to do with Lyme disease and usually goes away within a few days after the tick is removed. But if the skin near the bite is red a few days or weeks after you were bitten, it could be a sign of Lyme disease. A Lyme disease rash typically spreads outwards with a ring-like appearance until it reaches a diameter of more than five centimeters. This rash is called erythema migrans (Latin for "migrating redness"), or EM rash. Because of its typical appearance, it is also sometimes called a "bull's eye" rash.

Illustration: Typical signs of Lyme disease – as described in the articleTypical signs of Lyme disease

It is important to seek medical attention if you develop a rash like this. You should also see a doctor if you develop flu-like symptoms such as fever, headache, drowsiness or aching muscles within six weeks of being bitten. These symptoms could also be signs of Lyme disease, even if you don't have an EM rash.

If you do have a typical rash, Lyme disease can be diagnosed just by looking at it. Make sure you remember to tell your doctor that you were bitten by a tick. If it's still not possible to tell whether you have Lyme disease after having a physical examination, you may have a blood test.

What is the risk of getting Lyme disease from a tick bite?

It is estimated that about 1 out of 100 people who are bitten by a tick develop Lyme disease. The risk of Lyme disease will mainly depend on

  • how long the tick was attached to the skin, and
  • how old and big it was.

Large ticks are more likely to be infected with Lyme disease because they are older and will generally have fed on more host animals. Borrelia bacteria are found in all parts of Germany. The proportion of infected ticks varies greatly from region to region, and no reliable statistics are available.

Even if a tick is infected with Lyme disease, it will not necessarily transfer the bacteria when it bites. Unlike TBE viruses, the Borrelia bacteria live in the bowel of the tick, and not in its salivary glands. This means that the host will only become infected – if at all – after the tick has fed for quite a long time. That is why checking your body soon after spending time outdoors, and removing any ticks you may find, is an effective way to prevent Lyme disease.

Treatment and outlook

Lyme disease is treated with antibiotics. This medication is taken over a period of two to four weeks, depending on the symptoms. The disease then usually goes away without any complications. Sometimes, though, initial treatment with antibiotics isn't effective enough, and you might need to use different antibiotics.

The symptoms of Lyme disease may also get better without taking antibiotics, but then the disease is more likely to lead to more serious complications. If the bacteria spread within the body, the first symptom is a burning pain near the tick bite. About 3 out of 100 people then develop a disease called neuroborreliosis, in which the infection spreads to the brain and nerves. This can lead to paralysis (often affecting the face), painful nerve inflammations, or meningitis.

Another rare complication that can develop months or even years after someone is infected is called Lyme arthritis. This affects about 2 out of 100 people. Lyme arthritis arises if the infection spreads to the joints, causing painful inflammations and swelling. Very rare complications include heart problems and chronic inflammation of the skin.

Both neuroborreliosis and Lyme arthritis can be treated effectively with antibiotics and usually don't have any long-term effects. There are no exact statistics on the risk of developing serious complications if Lyme disease is not treated, or not treated properly.

Does it make sense to take antibiotics "just in case"?

No. People are advised not to take antibiotics to try to lower the risk of getting Lyme disease after being bitten by a tick. No studies have shown that taking them as a precaution has any advantages. Antibiotics may have side effects, too.

In any case, it's important to see a doctor if any of the above-mentioned symptoms arise.

Post-Lyme syndrome / “Chronic Lyme disease” – what does it mean?

People sometimes experience symptoms like achy muscles and joints, severe exhaustion or memory problems months or even years after being bitten by a tick. Some of the people affected by these problems and some doctors believe that the symptoms are a delayed complication of a Borrelia bacteria infection. This group of symptoms is sometimes referred to as post-treatment Lyme disease syndrome (PTLDS) or "Chronic Lyme disease" – although the latter is not generally accepted as a diagnosis.

These symptoms are sometimes linked to Lyme disease, even if the person wasn't known to have been bitten by a tick and the blood tests didn't show any evidence of infection. Then it is unlikely that the symptoms actually have anything to do with a Lyme disease infection. They may have been caused by any number of other medical conditions. Sometimes doctors recommend that people who have non-specific joint pain, states of exhaustion or trouble concentrating take antibiotics for a very long time. This is not advisable, though. If the symptoms aren't being caused by Lyme disease, the treatment won't be effective. What’s more, treatment with antibiotics has side effects and may lead to bacterial resistance.