Study in Germany Reveals New Findings About Tick-Borne Encephalitis Cases

According to a recent article, although the number of ticks are rising in Germany currently, the cases of tick-borne encephalitis have been surprisingly lower. Researchers found that this is due to uncomfortable temperatures in their usual habitats.

Tick-Borne Encephalitis (TBE)

Tick-borne encephalitis (TBE) is an important cause of viral infections of the central nervous system in eastern, central, northern and increasingly western European countries, and in northern China, Mongolia, and the Russian Federation. Tick-borne encephalitis virus is a member of the family Flaviviridae.

Approximately 10,000 – 12,000 clinical cases of tick-borne encephalitis are reported each year, but this figure is believed to be significantly lower than the actual number of clinical cases.

The vast majority of infections result from infected ticks, which often remain firmly attached to the skin for days. On rare occasions, infection can result from consumption of unpasteurized milk from infect goats, sheep or cows. People come in contact with the ticks during outdoor activities in forested areas up to an altitude of about 2000 meters. There is no direct person-to-person transmission.

Symptoms:

Most infections remain asymptomatic. In case of clinical illness, the incubation period for tick-borne encephalitis lasts 2–28 days (most commonly 7–14 days) and is followed by 1–8 days of general cold symptoms, such as fatigue, headache, and general malaise, usually combined with fever of ≥38 °C.

After an asymptomatic interval of 1–20 days, up to 15% of patients experience a second phase of the disease characterized by fever frequently exceeding 40 °C and signs of central nervous system involvement, such as meningitis (e.g. fever, headache, and a stiff neck), encephalitis (e.g., drowsiness, confusion, and sensory disturbances), myelitis, or radiculitis.

Encephalitis developing during this second phase may result in paralysis, permanent sequelae or death. About 1% of cases with neurological pathologies may die; higher fatality rates have been reported from the Russian federation, which may be related to a different virus subtype. Severity of illness increases with age of the patient, but fatalities have been reported from all age groups. There is no specific treatment for tick-borne encephalitis.

As Tick Populations Increase, TBE Cases Decrease

Researchers were baffled when tick season – spring and summer – began and cases of TBE did not increase. With more ticks being active during this time, it is more likely that people will be bitten. Although people who get TBE typically do not have any symptoms, there is still the risk of the disease leading to encephalitis and therein damaging the spinal cord. This led researchers to look further into this issue to understand how this came to be.

An Explanation

The researchers found that ticks are traveling to higher altitudes. In fact, the most TBE diseases are being found at altitudes of 500 to 700 meters. This is a result of lower areas becoming too hot for the ticks, which makes them uncomfortable and pushes them to move higher.

However, researchers stress that people should not grow wary of getting the disease. There are still risks, especially in northern areas, and caution should still be used.

In order to minimize your risk, researchers suggest avoiding tick habitats as much as possible. These habitats are usually sparse forests, forest edges, and any areas that have tall grasses or bushes.

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