Fact sheet: Ticks

Media reports about ticks can sometimes be frightening. There may be talk of “tick attacks” or “little bloodsuckers” that are increasing in number every year. News like this is often overly dramatic and can be misleading. Although ticks can carry and spread diseases, tick bites usually do not lead to health problems. The health problems caused by ticks are normally only temporary and not very serious. In fact, tick bites only rarely result in serious or lasting effects on health.

In this fact sheet we would like to give you a realistic idea of how likely you are to get ill if you are bitten by a tick. Please note that this information reflects the situation in Germany and may not be applicable to other parts of the world. You will also find out what you can do to prevent tick bites and possible complications.

What are ticks and where are they found?

Contrary to popular belief, ticks are not insects – they are spider-like arachnids. Adult ticks have eight legs, a round body and are no bigger than a few millimeters. When ticks feed on blood, their bodies get quite a lot bigger. In Europe, the most common kind of tick is called the castor bean tick. These ticks mostly feed on the blood of host animals like rodents and deer. These host animals may have disease-causing germs in their blood, so the ticks might become infected and later spread disease to humans.

Ticks survive the winter by living underground. As soon as the weather gets better, they become more active again and start looking for hosts to feed on  – either humans or animals. Ticks are active between about March and November. They usually live in grassy or woodland areas, parks and gardens, and prefer warm and damp conditions; for example in bushes and shrubs, at the edge of woods, as well as on forest paths and grass.

It is widely believed that ticks fall out of trees, landing on people below, but that is not true. Instead, they attach to you when you walk by and brush against whatever they are resting on, such as bushes. That is why dogs and cats often have ticks, because they walk through shrubs and bushes a lot.

How do ticks bite?

When ticks have found a host to feed on, they usually look for areas of the body with soft skin. They do not normally bite straight away, but sometimes crawl around the body for several hours, finally settling in places like behind the ears, along the hairline or in skin folds. Once a tick has found a suitable place to feed, it uses its mouthparts to cut through the host’s skin, inserts its feeding tube (which also serves as an anchor) into the wound and then sucks blood into its body until it is full.

It does not hurt when a tick latches on to your skin and feeds. If you do not find the tick and remove it first, it will fall out on its own once it is full. This usually happens after a few days, but it can sometimes take up to two weeks. Like when you have a mosquito bite, there may be redness around the site of the tick bite, and it usually itches too. Some people only notice that they have a tick when their skin starts to itch.

Which diseases can be spread by ticks?

The ticks found in Germany can mainly spread two diseases: Lyme disease (also called Lyme borreliosis) and tick-borne encephalitis (TBE). TBE leads to an inflammation of the brain (encephalitis) or the membranes surrounding the brain and spinal cord (meningitis). But the diseases will only be spread if the tick is infected with the bacteria or viruses in question, and also passes them on.

Lyme disease is a lot more common than TBE. Overall, TBE is rare, or does not even occur at all in many areas. Neither of these two diseases can be spread from one person to another. In other words: if someone is infected, they are not contagious to others. It can take up to two weeks for TBE to develop after a tick bite. Lyme disease can take even longer to develop.

Lyme disease

Lyme disease is an infectious disease caused by bacteria. At first the skin surrounding the tick bite becomes inflamed. After some time it may affect joints and various organs too. Lyme disease is more common than TBE but it usually does not 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 goes away within a few days after removing the tick. However, if the site of the tick bite turns red a few days or weeks after being bitten, it could be a sign of Lyme disease. The rash associated with Lyme disease is typically circular and spreads until it reaches a diameter of more than five centimeters. Because this rash usually clears in the center, it is also known as “bull’s-eye rash”.

It is important to see a doctor if you develop a rash like this. You should also see a doctor if you get flu-like symptoms such as a fever, headaches, fatigue or muscle pain within six weeks of being bitten by a tick. These symptoms could also be a sign of Lyme disease, even if you do not have a bull’s-eye rash.

Doctors can find out whether you have Lyme disease by giving you a physical examination. Make sure you remember to tell your doctor that you were bitten by a tick if you have symptoms. If a physical examination is not enough, you may have a blood test for Lyme disease.

How high is the risk of developing Lyme disease after being bitten by a tick?

The exact risk of getting Lyme disease from a tick bite is not clear. It is estimated that about 1 out of 100 people in Germany who are bitten by a tick develop Lyme disease. In 2011, just under 8,000 cases of Lyme disease were registered in the eight federal states of Germany where they have to be reported. The risk will mainly depend on

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

The bacteria that are responsible for Lyme disease – called Borrelia burgdorferi bacteria – are found all over Germany. But the proportion of infected ticks varies greatly from region to region, and no reliable statistics are available. Larger ticks are more likely to be infected because they are older and will generally have fed on more host animals.

Even if a tick is infected with Lyme disease, the bacteria will not necessarily spread when it feeds on a host. Unlike the TBE virus, Borrelia bacteria do not live in the ticks’ salivary (spit) glands, but in their bowel. This means that the host will only become infected – if at all – if the tick feeds 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: an infected tick will not normally spread Lyme disease if it is removed within 24 hours.

Treatment and course of the disease

Lyme disease is treated with antibiotics. These are taken over a period of 2 to 4 weeks, depending on the symptoms. Lyme disease usually goes away without any complications. Sometimes, though, initial treatment with antibiotics is not effective enough, and it might be necessary to use different antibiotics.

The symptoms of Lyme disease can also get better without taking antibiotics, but then the disease is more likely to take a more severe course. If the bacteria spread within the body, the first symptom is a burning pain at the site of the tick bite. In rare cases a condition called neuroborreliosis can arise. Here the infection spreads to the brain and nerves. This can lead to paralysis (often affecting the face), a painful inflammation of the nerves or meningitis.

Another rare complication that can develop months or even years after someone is infected is called Lyme arthritis. This happens if the infection spreads to the joints, causing a painful inflammation and swelling. Very rare complications include heart problems and chronic inflammation of the skin.

Both neuroborreliosis and Lyme arthritis are treated with antibiotics and usually do not 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.

Opinion is divided on whether it is a good idea to take antibiotics as a precautionary measure after being bitten by a tick, to try to lower the risk of getting Lyme disease. Previous research has focused on people who had been bitten by tick species that do not live in Europe. Because the ticks that are found in Europe are sometimes infected with other types of Borrelia bacteria, it is not clear whether the research findings are applicable to Germany. In any case, it is important to see a doctor at the latest if any symptoms arise.

Post-Lyme syndrome / “chronic Lyme disease”

People sometimes experience symptoms like achy muscles and joints, exhaustion or memory problems months or even years after being bitten by a tick. Some of those affected and some doctors believe   that these symptoms are caused by a chronic Borrelia bacteria infection. Other people who have these symptoms are not aware that they were ever bitten by a tick, and blood tests do not give any reason to believe that they were, but the symptoms are still thought to be a result of Lyme disease. This condition is sometimes called post-Lyme syndrome or “chronic Lyme disease” – even if the latter is not a generally accepted diagnosis.

There is some disagreement as to whether these symptoms are in fact linked to an infection with Borrelia bacteria. They are non-specific and can also be caused by many other medical conditions. Sometimes doctors recommend taking antibiotics for a very long time. But there is no scientific proof that this approach is effective. We do know, however, that antibiotics have side effects.

Tick-borne encephalitis (TBE)

The risk of getting TBE is much lower than the risk of getting Lyme disease. Only a small proportion of ticks are infected with the virus. And even if a tick is infected, the virus will not necessarily spread to the people the tick feeds on.

If the infection does spread, some people will develop symptoms. In children the infection often goes unnoticed, or the symptoms are only mild and temporary. The symptoms of a mild TBE infection are similar to flu symptoms: fever, headaches, vomiting and dizziness.

Sometimes people feel better for a while and then symptoms such as fever, vomiting and headaches come back again. They may also have symptoms like impaired consciousness, coordination problems or paralysis. These symptoms are caused by the infection of the brain or meninges. Paralysis is usually temporary, but in rare cases it can become permanent. TBE very rarely leads to such serious complications in children. They are more common in adults though. TBE can be fatal, but this is extremely rare.

It is also extremely rare for the infection to spread to the spinal cord (myelitis), which can lead to muscle weakness, paralysis and sensory disturbances. This is more common in older people than it is in younger people. Of those people who are infected with TBE,

• about 70 out of 100 have a mild form and
• about 30 out of 100 have a severe form.

It is estimated that encephalitis will be fatal in 1 out of 100 people who develop it. A total of about 400 cases of TBE (mild and severe forms) were reported in Germany in 2011 – most of them were in the states of Bavaria and Baden-Württemberg.

TBE is diagnosed by testing blood or cerebrospinal fluid for the TBE virus.

How high is the risk of developing TBE after being bitten by a tick?

The likelihood of getting TBE following a tick bite can only be very roughly estimated. Hardly any of the ticks in the north of Germany, in particular, are infected with TBE. Some regions of Germany have been declared “TBE risk areas”.  These are districts in which TBE infection is more common than in other areas. A district is considered to be a “TBE risk area” if at least 1 out of 100,000 people living in that district, or in that area including all neighboring districts, had a TBE infection within the last five years. So far, between 1 and 40 out of 100,000 people living in such areas have developed TBE within a time period of five years.

In other words: The risk of getting TBE is very low, even in “TBE risk areas”. The German federal states with the highest occurrence of TBE are Baden-Württemberg, Bavaria, Hesse, Rhineland-Palatinate and Thuringia. You will find a map of the “TBE risk areas” in Germany on the Robert Koch Institute website. This shows in more detail which districts are associated with a higher risk of infection. But even in the “TBE risk areas” in the south of Germany, only a small proportion of the ticks are infected with TBE. It is estimated that 0.1 to 5% of the ticks that live there carry the virus.

Disease-carrying ticks are also found in other countries. TBE is most commonly found in Eastern Europe – for instance, in some regions of Russia, the Czech Republic, Lithuania and Poland. The risk of infection is also higher in some areas of Austria, Hungary, Croatia, Sweden and Finland. But the virus is only rarely found in Italy, Greece, Norway and Denmark. TBE does not occur at all in Great Britain and the Benelux countries (Belgium, the Netherlands and Luxembourg).

Treatment and course of the disease

So far, there is no treatment that specifically fights the TBE virus. Instead, treatment only focuses on relieving the symptoms. Because TBE is caused by a virus, antibiotics do not help. No antiviral drugs are currently available.

Although TBE usually clears up without any lasting health problems, the symptoms can last for months. In very rare cases it can be fatal. Serious complications are quite a lot more common in adults than in children. Children normally only have a mild form of TBE: serious symptoms are rare and there are hardly ever any lasting effects.

When can it make sense to have a TBE vaccination?

The TBE vaccination can only protect you against the TBE virus, not against Lyme disease, which is quite a lot more common. Research has shown that most people who have the vaccination develop antibodies against the TBE virus. These antibodies stop the TBE virus from spreading within the body.

The vaccination consists of three injections. The second injection is given about 1 to 3 months after the first injection, and the third injection is given after another 5 to 12 months. A booster injection after 3 to 5 years is recommended. Within 2 to 4 weeks of the first injection a lot of people will already have temporary immunization protection. In principle, children can be vaccinated against TBE too, but their risk of serious complications from TBE is much lower than that of adults anyway.

The vaccination quite often has temporary side effects, including fever, dizziness, headaches, tingling or nausea. In very rare cases it can lead to more serious problems, such as nerve damage.

The German Standing Vaccination Committee (Ständige Impfkommission, STIKO) recommends having a TBE vaccination if you spend a lot of time outdoors in a “TBE risk area”. The statutory health insurance funds in Germany cover the cost of the vaccination for people who live in “TBE risk areas”. If you are planning to travel to a higher risk area, contact your health insurance fund beforehand to find out whether they will pay for the vaccination. The immunization of people in certain professions, such as agriculture and forestry, is paid for by their employer.

How can I protect myself from ticks?

The risk of being bitten by a tick will to a great extent depend on where you are and what you do when outdoors in nature. For example, it is recommended that you wear closed shoes when walking through tall grass or shrubs. Wearing clothes that cover as much of your skin as possible – such as long trousers and long sleeves – makes it more difficult for ticks to attach themselves to you. It is easier to see ticks on light-colored clothing than on dark clothing.

Ticks sometimes crawl around on your body for a few hours before biting. So it is a good idea to check yourself for ticks soon after returning from a walk in grassy or woodland areas, and remove any ticks you might find – perhaps even before they have attached themselves. Children generally do not remember to do things like this, and may need to be reminded or helped. Adults can also ask someone for help, particularly when checking for ticks in places that they cannot see themselves.

According to the German Robert Koch Institute, tick repellent sprays can offer temporary protection from ticks. Their effect wears off after two hours.

How do I remove ticks?

Removing ticks as soon as possible can lower the risk of getting Lyme disease. It is important not to squeeze the tick while removing it, because then the Borrelia bacteria might be squeezed out of the tick and into your body. You can avoid this by doing the following:

• Slide a thin object between your skin and the tick. You could use tick tweezers or a tick-removal card, for example. Normal tweezers are also an option, if the tips of the tweezers bend inwards. If nothing else is available, you can use long fingernails too.  
• Slowly push or pull the tick out of your skin.  
• Once you have removed the tick, you can disinfect the site of the tick bite and inspect it to see whether you managed to remove all of it. For instance, if you see a small dark dot, the mouthparts may have been left behind. This does not pose any particular danger. A doctor can remove the rest of the tick.

Covering the tick in things like nail polish, glue, toothpaste, alcohol or oil before removing it could increase the risk of infection. You will find a more detailed description in our information "Removing ticks".

What does this mean in my case?

Whether or not someone is worried about ticks will depend on how at risk he or she feels personally. A lot of people enjoy spending time outdoors, do not consider ticks to be dangerous, and do not want to worry about what clothes to wear when out and about in nature. But others find it important to protect themselves as best as possible, are careful about what they wear and make sure they get vaccinated before heading to a “TBE risk area”.

You can lower your risk of Lyme disease and TBE by being aware of ticks and checking your body and your children’s bodies after spending time outdoors.  After a tick bite, is important to watch out for symptoms that could be a sign of a tick-borne disease, and then see a doctor if any arise. And having a realistic idea of the health risks associated with ticks can make it easier to deal with them.

Author: Institute for Quality and Efficiency in Health Care (IQWiG)

Next planned update: April 2015. You can find out more about how our health information is updated in our text "Informed Health Online: How our information is produced".

© IQWiG (Institute for Quality and Efficiency in Health Care)