A total of 212 confirmed cases have been reported to The Public Health Agency of Sweden (Folkhälsomyndigheten) so far this year, sharply increasing from late July onwards. That's twice as many as in a normal year.
But Sweden has not yet seen the end of it, the authority warned on Monday.
“Since the number of cases (of rabbit fever) is usually at its highest in September, the outbreak is expected to grow further in the coming weeks,” it wrote in a statement.
Most cases have been reported in Dalarna, Gävleborg and Örebro counties in central Sweden, but in the past week Västerbotten and Norrbotten have also seen an increase, often limited to a specific area.
Many of those affected by the disease have been infected via mosquito bites.
The purple line shows the number of reported cases of rabbit fever this year until August 9th, and the other line the annual average from 2009-2018. Photo: The Public Health Agency of Sweden
The animals most likely to carry the disease are wild hares, hence the name rabbit fever (also known as tularemia in English or harpest in Swedish), and rodents, but it can also be transferred to humans via mosquito bites and occasionally tick bites.
The health agency said the best way of protecting yourself against the infection is to wear long sleeves and mosquito repellent, and avoid being in close contact with dead animals.
It's also possible for the infection to be transmitted by inhaling dust or drinking water which is contaminated by urine or faeces from animals with the disease, according to Swedish healthcare service 1177. The disease cannot be carried from human to human.
Symptoms of rabbit fever typically begin with swelling or tenderness in the lymph node and a skin lesion at the site of any bite or direct contact, followed occasionally by symptoms which can include a skin rash, nausea, and headaches.
Sweden had a large outbreak of rabbit fever in 2015, when 859 people across the country suffered from the illness, the majority of them in Norrbotten and Västerbotten. In 2018, 107 cases were reported across Sweden, with Dalarna the most severely affected region.