Dangerous taiga tick found in Sweden

The feared taiga tick, a parasite that can carry a dangerous form of tick-borne encephalitis (TBE), has spread to Sweden, local media reported Wednesday.

According to Swedish Television, the range of taiga ticks, also known as Ixodes persulcatus, has recently increased in Russia and Finland. During a study, the tick was also detected in nine out of 36 field localities in the Bothnian Bay area in Sweden.

The taiga tick has never before been recorded that far north and dog owners in the region said their dogs became tick-infested for the first time seven to eight years ago. Moose, hares, domestic dogs and ground-feeding birds are the most likely carriers of taiga ticks in northern Sweden, the report said.

The taiga tick is closely related to the most common tick species in Sweden, the Ixodes ricinus. To a layman they look identical, Thomas Jaenson, a professor in medical entomology at the Uppsala University, told Swedish Television.

"It's hard to tell the difference," said Jaenson, "You need a good microscope. But they behave differently. Among taiga ticks it is often the adult females who suck blood from humans whereas among the 'common' tick it is more often the nymphs."

The tick more commonly found in Sweden, the Ixodes ricinus, spreads a form of TBE disease that has an average 1 percent mortality rate. By comparison, the taiga tick spreads a more aggressive and dangerous form of the disease called Far Eastern, which can have a mortality rate of up to 30 percent.

The Far Eastern disease has been recorded in Estonia and has caused several deaths in Russia.

So far, researchers have found no signs of Far Eastern disease in Finland or in Sweden, but there is a chance it could come there via birds who are either infected themselves or who carry the tick, Jaenson said.

He added the taiga tick thrives in cold climates and could spread to other parts of Sweden, beyond the Bothnian Bay area. Endit