The local Sundsvalls Tidning newspaper reported that the town's mental health clinic for convicts (rättspyk) was fighting an "unusual" number of vipers (huggormar). While there had been snakes on the property last year, their numbers shot up this spring.
A patient who was spending time in the yard picked one of the adders, which coiled, turned, and bit him. At the time, five snakes were crawling across the yard.
"There's an unusual number of snakes this year," said clinic manager Bengt Eriksson.
The patient whose hand was bitten did not need medical care, despite the vipers being the only venomous species of snake in Sweden.
"All you could see were two small fang marks," Eriksson noted.
The clinic has now asked the property owners Riksbyggen to remove the snakes from the premises.