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Lyme disease (borreliosis)

Borreliosis, also known as Lyme disease or Lyme borreliosis, is caused by a spiral-shaped bacterium called "Borrelia burgdorferi". Borrelia are the most frequently transmitted pathogens by ticks in Germany. Although recognized as a disease for more than 100 years, it was only in 1982 that Willy Burgdorfer discovered that bacteria residing in the intestines of ticks, were the cause. It is estimated that tens of thousands of people catch the disease in Germany each year.

Lyme disease is caused by a spiral-shaped bacterium called "Borrelia burgdorferi".

Symptoms and progression of Lyme disease

The symptoms of Lyme disease can vary, though most of them are not specific. The most common symptom of borreliosis is the typical ring-shaped redness (Erythema migrans) surrounding the location of the tick bite. It may be observed in the first few days following a tick bite, but could also take several weeks to develop.

However, it does not appear for all Lyme disease patients. Other than the rash, there are also more general symptoms observed in the early stages of borreliosis, such as fatigue, fever and headaches.

If left untreated, other symptoms can follow, ranging from severe pains and heart problems to meningitis. A facial paralysis can also be observed relatively often. Arthritis also frequently appears during the later chronic stages.

How do you catch it?

In Germany, the bacteria causing Lyme borreliosis are the most frequently transmitted pathogens by ticks.

According to current scientific knowledge, it is only possible to become infected with the bacteria that causes Lyme disease from a tick bite. Lyme disease patients are not contagious. As Borrelia reside in the midgut of a tick, it takes a while before the bacteria can be transmitted to the bloodstream of the host. Since it can take hours for the bacteria to reach the bloodstream during the tick feeding process, a quick removal of the tick can lower the risk of contracting Lyme disease.

Currently, there is no way to vaccinate against Lyme disease. It is also possible to become infected several times and suffer multiple cases of Lyme disease at different stages simultaneously. Lyme disease occurs everywhere in the world, wherever there are ticks. Several tick species are known to transmit Borrelia. In Europe, the castor bean tick (Ixodes ricinus) is the primary culprit. Disease pathogens are unevenly distributed in the tick populations. According to the Robert Koch-Institute, between 5 to more than 35 percent of ticks may carry Borrelia, depending on the region. On average the likelihood of contracting Lyme disease after a tick bite is between 1.5 and 6 percent. The longer the tick is allowed to feed, the higher the risk of an infection.

Nevertheless, not everyone that comes into contact with Borrelia from a tick bite will actually fall ill. Often the body succeeds in keeping the bacteria in check – the infection causes no symptoms and heals without consequences. That is why Borrelia antibodies can be detected in the blood of many healthy people. Up to 25 percent of people carry these antibodies – without ever becoming ill with Lyme disease. Only 0.5 to 1.5 percent of those bitten by a tick actually fall ill.

Diagnosis of Lyme disease

The clearest indication of Lyme disease for a doctor is an "Erythema migrans", an extensive doughnut-shaped redness. Such a rash often develops around the site of a tick bite, but can also appear on other parts of the body. As it can take up to 28 days before the rash appears, it is important to regularly check the site after being bitten.

When there is an orbital rash and the patient remembers being bitten by a tick, the doctor will prescribe a course of antibiotics to treat borreliosis. Sending a blood test to a laboratory is ineffective, because it is usually impossible to detect antibodies to Borrelia in the early stages of an infection. Conversely, the presence of antibodies at this stage is no evidence of Lyme disease manifesting itself, as these can often be found in the blood of healthy persons.

The diagnosis of Lyme disease in the later stages presents greater difficulties. An orbital rash is usually no longer visible at this time. Many patients will no longer remember been bitten by a tick, because considerable time will have already passed, sometimes even years. The doctor must carefully study the symptoms the patient presents – such as changes to the skin, joint complaints or facial paralysis – as well as consider the possibility of other diseases that may have similar symptoms. A positive laboratory test offers no sure diagnosis and also increases the risk that the true cause is overlooked. However, when a blood test for Borrelia antibodies is negative, the doctor can almost certainly exclude the possibility of Lyme disease in its late stages.

Treatment of Lyme disease

As Lyme disease is caused by bacteria, it is easily treated with antibiotics in its early stages. During later stages of the disease, a course of antibiotics by infusion for several weeks is often necessary.

Protect yourself!

Anyone taking a nature walk should avoid clothes that reveal skin and tuck trouser legs into socks.

The best protection against Lyme disease is to avoid tick bites altogether. It also helps to remove ticks as soon as they are found on the body. As a tick bite is usually not painful, you should check your entire body for ticks after spending any time in nature. Finding out where on the body the tiny parasites prefer to bite was recently determined in a nationwide study.

Taking antibiotics as a prophylactic following a tick bite is not recommended. To test the tick for pathogens following a bite is also not advised. Even if a tick does contain pathogens, in only a fraction of the cases do they lead to the disease. Currently, there is no vaccine available for humans.

Source: Robert Koch-Institute. (2007) Lyme borreliosis. A guide for doctors. [Online] Available at: https://www.rki.de/DE/Content/Infekt/EpidBull/Merkblaetter/Ratgeber_LymeBorreliose.html Last accessed: 25 Oct. 2016"