The most important questions and answers about tick season
Published: Wednesday, Apr 17th 2024, 12:10
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With increasingly mild winters, experts say that ticks are also becoming active earlier and earlier in Switzerland. The arachnids can transmit various diseases, including potentially fatal ones. The most important questions and answers:
WHERE AND WHEN DO TICKS BECOME ACTIVE?
Ticks feel at home in a warm and humid environment. They can be found in forests and parks, but also in gardens on grasses, ferns and shrubs. According to the Federal Office of Public Health (FOPH), the tick season begins in March and ends in October.
Depending on the weather and from a temperature of around seven degrees Celsius, the animals can also become active earlier. Due to mild winters, ticks are now active all year round, experts recently explained at a media conference in Hohenheim (Germany) on the occasion of the South German Tick Congress in February.
WHERE ARE THE RISK AREAS?
Experts have been observing for some time that ticks are increasing their activity due to climate change and mild winters. In Switzerland, the entire Central Plateau, the foothills of the Alps and Ticino are now considered risk areas for tick bites. The small animals are also active at ever higher altitudes of up to 2000 meters.
Information on risk regions can be found on the "Tick model" map on the federal geoportal. There is also the "Tick" app developed by the Zurich University of Applied Sciences (ZHAW). This shows the current tick risk potential in the area and the correct behavior in the event of a bite.
WHAT DISEASES DO TICKS TRANSMIT?
According to the FOPH, the most common tick-borne pathogens in Switzerland are tick-borne encephalitis (TBE) and Lyme disease (also known as Lyme borreliosis). The TBE virus can cause meningitis. The FOPH recommends vaccination from the age of six.
Lyme disease is a bacterial pathogen that normally occurs as a flu-like illness. However, it can also lead to skin problems, vision problems, paralysis and heart problems. In contrast to TBE, cases of Lyme disease do not have to be reported. Ticks can also transmit the less common infectious disease tularemia (also known as "rabbit plague") to humans, which must be reported. Without treatment, the disease can be fatal.
The list of tick-borne pathogens is getting longer and longer, according to the latest report from the Institute of Virology at the University of Zurich (UZH). In 2022, Alongshan virus (ALS), which was discovered in China in 2017, was detected for the first time in tick samples in several regions of Switzerland. The virus is associated with fever, headaches and more severe symptoms. According to the FOPH, there is no vaccination against the ASL virus.
DO ALL TICKS TRANSMIT DISEASES?
However, Swiss ticks are more dangerous than previously thought. Researchers have found viruses or bacteria in almost every tick, as a study published in November 2023 showed. These include the Alongshan virus, which was only discovered a few years ago.
"Almost every tick can potentially make you ill," said Cornel Fraefel, a virologist from the University of Zurich (UZH) who was involved in the study, when asked by the Keystone-SDA news agency. "We found several pathogens in many ticks at the same time." 77.2 percent of the ticks examined tested positive for at least one non-viral pathogen. Among the ticks collected in urban areas, the figure was as high as 83.9 percent.
WHAT IS THE FORECAST FOR 2024?
Experts at the FOPH, the UZH and the ZHAW are following the trends in diseases following tick bites and the spread of the animals. The number of cases of diseases following tick bites is expected to remain high. This is suggested by the development in recent years.
Ticks also have hardly any problems with prolonged dryness. The actual development is still dependent on the weather and the number of people who spend their free time outdoors.
According to the FOPH, tick-borne diseases can occur all year round, depending on location and exposure risk (e.g. occupation, protective measures and vaccination status) as well as tick activity and climatic conditions.
Experts are expecting a large number of TBE infections this year - including in Switzerland, according to a statement at the Southern German Tick Congress. It has also been observed that a high number of TBE cases have recently been reported every two years and not every three years as in the past. This is also to be expected in 2024.
In terms of case numbers, the general trend is clearly pointing upwards. "Infection figures are always subject to annual fluctuations, but the longer-term trend is clearly pointing upwards," emphasized Rainer Oehme, Head of Laboratory at the Baden-Württemberg State Health Office. The experts also warned of a high number of unreported cases.
©Keystone/SDA
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