Tularemia Goes West: Epidemiology of an Emerging Infection in Austria

Abstract

The zoonotic disease tularemia is caused by the Gram-negative bacterium Francisella tularensis, with the two major subspecies tularensis and holarctica being responsible for infections in humans and animals. The F. tularensis subspecies holarctica is less virulent and prevalent in Europe and Asia. Over the last few centuries, few epidemic outbreaks and low numbers of infections have been registered in the eastern part of Austria, specifically in the provinces of Lower Austria, Burgenland, and Styria. The reported infections were mostly associated with hunting hares and the skinning of carcasses. Within the last decade, ticks have been identified as important vectors in Tyrol and served as first evidence for the spread of F. tularensis to Western Austria. In 2018, the pathogen was detected in hares in the provinces of Tyrol, Vorarlberg, and Salzburg. We presume that F. tularensis is now established in most regions of Austria, and that the investigation of potential host and vector animals should be spotlighted by public institutions. Tularemia in humans presents with various clinical manifestations. As glandular, ulceroglandular, and typhoidal forms occur in Austria, this infectious disease should be considered as a differential diagnosis of unknown fever.

Keywords: Austria; F. tularensis; epidemiology; tularemia.

Figure 1

Cumulative cases of human tularemia in Austria divided by provinces from 1990–2019. Abbreviations: V = Vienna, B = Burgenland, LA = Lower Austria, UA = Upper Austria, C = Carinthia, ST = Styria, S = Salzburg, T = Tyrol, VO = Vorarlberg [82].

Figure 2

Summative geographic distribution of human tularemia cases in the various Austrian provinces from 1990 to 2019. The size of the dots corresponds to the number of humans infected with F. tularensis during a five year period [82].