Prevalence of ticks infected withFrancisella tularensis in natural foci of tularemia in western Slovakia

Abstract

The prevalence of ticks infected with F. tularensis was followed during a systematic surveillance in endemic area of tularemia in western Slovakia over the years 1984-93. Ticks were collected from vegetation in localities of Podunajské Biskupice, in the vicinity of the capital of Slovakia, Bratislava, near the river Danube. In total 6033 ticks, mostly adults of Dermacentor reticulatus and Ixodes ricinus (4994 and 1004, respectively) and 35 nymphs of Haemaphysalis concinna, were examined for the presence of F. tularensis. Out of 4542 starving ticks, 34 F. tularensis strains were isolated predominantly from D. reticulatus (30), and to a smaller extent also from I. ricinus (3) and H. concinna (1). Natural infection with F. tularensis was further proved from 1491 adults of D. reticulatus fed on laboratory animals, rabbits and white mice, together in 27 cases. From that, 21 times it was by positive isolation either from suspensions of partly or fully engorged ticks and their feaces, or from spleens of animals dead after the feeding of ticks. In addition, solely the development of antibodies against the agent was confirmed in 6 rabbit hosts. The presence of F. tularensis in all the above mentioned tick species and namely the relatively high and permanent infestation of D. reticulatus adults, ranging between 0.5-2% during the followed time period, demonstrated the maintenance of active natural focus of tularemia in the area under study. The present paper also emphasizes the epidemiologic consequence of various species of ticks in endemic foci of tularemia and the aspect of possible ways of transmission of the agent to humans.

The status of tularemia in Europe in a one-health context: a review

“…tularensis persisted in tick populations at prevalence rates of 2-4% for 4 years in Martha's Vineyard [94]. Similarly, in Europe, Gurycová et al [53] found that F. tularensis subsp. holarctica persisted at prevalence rates of 0·2-1% in ticks in western Slovakia for 6 years in an area in which tularemia was endemic.…”

“…The range of arthropod vectors connected with tularemia has expanded to include ticks [19,40,[53][54][55][56][57][58][59][60], mosquitoes [56,61], horse flies [56], fleas [62] and gamasid mites [3]. In Europe, much of the research on the role of arthropod vectors in the transmission of F. tularensis subsp.…”

Susceptibility of the Common Hamster (Cricetus cricetus) to Francisella tularensis and Its Effect on the Epizootiology of Tularemia in an Area Where Both Are Endemic

“…holarctica strain isolated from a European brown hare (Lepus europaeus) in 2007 (Permit number for animal challenge: 22.1/2703/003/2009). One animal was infected intramuscularly on its hind leg (case 1) with 10 3 colonyforming units (CFU), as ticks harbor high infectious doses of F. tularensis (Gurycová et al, 1995), and one orally with 10 5 CFU (case 2), a dose used in earlier studies in similar Class 1 species, in voles (Microtus pennsylvanicus and Microtus rossiaemeridionalis) (Olsufiev and Dunayeva, 1970;Bell and Stewart, 1983;Olsufiev et al, 1984;Sjö stedt, 2007). Hamsters were checked three times a day to record clinical symptoms.…”

Tularemia in Denmark: Identification of a Francisella tularensis subsp. holarctica Strain by Real-Time PCR and High-Resolution Typing by Multiple-Locus Variable-Number Tandem Repeat Analysis

“…The tick species was not determined. In central Europe, ticks of the species Ixodes ricinus and Dermacentor reticularis have been shown to be naturally infected with F. tularensis, at a prevalence of 0.1 to 0.2% (6,8,22).…”