Airborne Tularemia in Sweden

Abstract

In the autumn of 1966 an outbreak of tularemia started in Northern Sweden. Totally 676 cases were reported. In Sweden tularemia is usually transmitted by mosquitos or through direct contact with infected hares. In the present outbreak epidemiological, bacteriological and clinical data indicated that the infection was generally transmitted through inhalation of dust from hay contaminated with vole faeces. The clinical picture in this outbreak was dominated by general symptoms, such as high temperature, fatigue, malaise, and severe headache. Many of the patients showed signs of pneumonia or other respiratory symptoms. Extensive serological investigations indicated that in some areas over 20% of the total population had been infected. In 16–32% of the serologically verified cases the infection was subclinical.