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Background: Tularemia, which is caused by the intracellular bacterium Francisella tularensis, exist in several different forms: ulceroglandular, oculoglandular, typhoid (septic), pulmonary and oropharyngeal. Sweden experiences recurrent epidemics with irregular intervals and geographical localizations, and the infection is classified as notifiable. The infection is usually treated using ciprofloxacin or doxycycline although aminoglycosides is an option.

Methods: Cases were extracted from the County of Norrbotten database of notifiable diseases and were analyzed with respect to geographic localization, clinical presentation, and a number of other parameters.

Results: A total of 406 cases in the county were reported between July and November of 2015, with a peak in late August. This is a 100-fold increase compared to 2014 and a 10-fold increase compared to 2013.The incidence differed considerably between communities in the county and were up to 330 cases per 100,000 with a mean incidence of 160 cases per 100,000 inhabitants. Cases tended to cluster around bodies of water, where mosquitoes are more prevalent. The ulceroglandular form was dominant with 80% of reported cases, although typhoid, pulmonary, and oropharyngeal cases were reported. Most cases were diagnosed using PCR and/or serology, although some ulceroglandular cases were diagnosed presumptively based on a typical ulcer, palpable nodes, and fever. Most cases were treated by primary care physicians using ciprofloxacin with a high success rate, although doxycycline was sometimes used.

Conclusion: The epidemic, which is the biggest in the County of Norrbotten so far, and one of the biggest in Sweden ever, demonstrates that tularemia is a disease that needs to receive more attention, at least in the northern parts of the country.