A total of eight cases of the disease have been reported so far, with patients in Germany, Switzerland, and the Czech Republic also having been infected.
All of those affected by the disease suffer from a weakened immune system, the Dagens Nyheter (DN) newspaper reported.
The illness, which researchers call “neo disease” after the bacteria which causes it, Candidatus Neoehrlichia mikurensis, also brings about flu-like symptoms with long-lasting high fevers, coughing, and aches.
The disease can be treated with antibiotics.
The first case was discovered in the summer of 2009 after a 77-year-old man from Gothenburg came down with a high fever and lost consciousness.
During his treatment, doctors discovered blood clots in his leg and lungs. The man’s fever returned several times and doctors eventually found traces of an unknown bacteria in his blood.
The disease, which is transmitted by ticks, had never before been reported in Sweden and it was unclear what caused the disease in humans.
The two additional Swedes who have become ill due to the bacteria are in their sixties and seventies.
It remains unclear why the disease causes blood clots, but researchers have a number of theories in mind.
“When the body can’t deal with an infection in the blood, it traps the infection in a blood clot,” Christine Wennerås, a professor at Sahlgrenska University Hospital in Gothenburg, told the newspaper.
According to researchers, ten percent of ticks in southern Sweden carry the bacteria.