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Dangerous strain of tick-borne encephalitis spreads

A dangerous strain of Siberian subtype tick-borne encephalitis has gained ground in Finland, says a new report scheduled for release. The disease is incurable once manifested, but anti-inflammatory drugs can provide symptomatic relief in some cases. The virus affects the central nervous system, leading to death in two percent of cases within a week of onset.

Punkki kiinnittyneenä ihmisen iholle.
Two strains of tick-borne encephalitis have been discovered in Finland: the Western European subtype from the West and the more dangerous Siberian subtype from the East. Image: Antti Heikinmatti / Yle

A serious strain of tick-borne encephalitis has begun to emerge in several areas of Finland. A soon-to-be- published report outlines that several cases of the virus have been observed in the region surrounding the south-eastern city of Kotka in recent years.

“When the TBE cases came to light, researchers collected tick samples in the archipelago. The viruses they carried were isolated and analysed, and it became clear that it was the Siberian subtype of the tick-borne encephalitis virus that we were dealing with,” says Olli Vapalahti, a TBE researcher professor at the University of Helsinki.

The symptoms in the cases of the Kotka infections were very severe.

“The patients had high fevers and complained of severe headaches for several days. Some displayed signs of paralysis and two were declared unfit for work as a result,” says Ilkka Pieninkeroinen, chief neurological physician at the Kymenlaakso Central Hospital.

Twenty such cases have been diagnosed in Finland to date, with previous incidences discovered in the western coastal city of Kokkola. Few patients have perished as a result.

“The only treatments are measures to support the body’s basic functions, like hydration. Some antibiotics are also normally given in the early stages, when we haven’t yet established the cause of the symptoms,” says Pieninkeroinen.

Most of the people who have been infected are left with some kind of permanent damage to their central nervous system. Irritability, memory loss and concentration problems are common, along with hearing difficulties, muscle weakness and partial paralysis.

Transmitted by migratory birds

Finland’s Health and Welfare Institute THL states that a record number of 47 tick-borne encephalitis cases were reported in Finland last year. In many cases, it remained unclear whether the strain was of the Siberian or the Western European subtype.

“The type of virus is rarely indentified when the patient becomes ill. We have developed a test that would determine the subtype as part of the blood antibody test. Preliminary tests show that it is effective,” says Professor Vapalahti.

Ticks that carry the TBE virus usually come to Finland as individual outliers. Vapalahti says they do not spread to new areas of their own accord; rather they are carried to islands and peninsulas by migratory birds.

Vapalahti recommends that those people living next to high-risk coastal areas take the TBE vaccination, which has proven to be very effective in combating the virus.

“The vaccine is the only sure way to protect against TBE. Checking for ticks on your skin is not helpful in this scenario, as the infection starts in so quickly. It is a serious disease and the vaccine is a considerable benefit in relation to the risk.”  

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