Abundance of Ixodes ricinus and prevalence of Borrelia burgdorferi s.l. in the nature reserve Siebengebirge, Germany, in comparison to three former studies from 1978 onwards

Abstract

BackgroundDuring the last decades, population densities of Ixodes ricinus and prevalences of Borrelia burgdorferi s.l. have increased in different regions in Europe. In the present study, we determined tick abundance and the prevalence of different Borrelia genospecies in ticks from three sites in the Siebengebirge, Germany, which were already examined in the years 1987, 1989, 2001 and 2003. Data from all investigations were compared.MethodsIn 2007 and 2008, host-seeking I. ricinus were collected by monthly blanket dragging at three distinct vegetation sites in the Siebengebirge, a nature reserve and a well visited local recreation area near Bonn, Germany. In both years, 702 ticks were tested for B. burgdorferi s.l. DNA by nested PCR, and 249 tick samples positive for Borrelia were further genotyped by reverse line blotting.ResultsA total of 1046 and 1591 I. ricinus were collected in 2007 and 2008, respectively. In comparison to previous studies at these sites, the densities at all sites increased from 1987/89 and/or from 2003 until 2008. Tick densities and Borrelia prevalences in 2007 and 2008, respectively, were not correlated for all sites and both years. Overall, Borrelia prevalence of all ticks decreased significantly from 2007 (19.5%) to 2008 (16.5%), thus reaching the same level as in 2001 two times higher than in 1987/89 (7.6%). Since 2001, single infections with a Borrelia genospecies predominated in all collections, but the number of multiple infections increased, and in 2007, for the first time, triple Borrelia infections occurred. Prevalences of Borrelia genospecies differed considerably between the three sites, but B. garinii or B. afzelii were always the most dominant genospecies. B. lusitaniae was detected for the first time in the Siebengebirge, also in co-infections with B. garinii or B. valaisiana.ConclusionsOver the last two centuries tick densities have changed in the Siebengebirge at sites that remained unchanged by human activity since they belong to a nature reserve. Abiotic and biotic conditions most likely favored the host-seeking activity of I. ricinus and the increase of multiple Borrelia infections in ticks. These changes have led to a potential higher risk of humans and animals to be infected with Lyme borreliosis.

Heterogeneity in the abundance and distribution of Ixodes ricinus and Borrelia burgdorferi (sensu lato) in Scotland: implications for risk prediction

“…Sampling variation could contribute to a proportion of the observed variation, however the sample size of nymphs collected at each site ( n  = 200) was chosen to be high to minimize this. Variation in prevalence between years has also been reported at sites sampled over several years in Europe [71, 72] and North America [73], although a recent study in the Netherlands found surprisingly little inter-year variation at all sites [74]. …”

“…Another longitudinal study carried out in the Netherlands, in which B. afzelii was the dominant genospecies, found an alternating annual trend in prevalence at three out of four sites [71]. A decrease in B. afzelii prevalence between consecutive years was also noted at several sites in a study from Germany [72]. Rodent species are the most competent hosts for B. afzelii [16].…”

Europe-Wide Meta-Analysis of Borrelia burgdorferi Sensu Lato Prevalence in Questing Ixodes ricinus Ticks

“…A number of field studies have already pointed to increases in average densities and activities of questing ticks in parts of Europe with long-documented I. ricinus populations (14,15). Moreover, the distributional area of I. ricinus appears to be steadily shifting toward higher altitudes and latitudes, increasing the total surface area of tick-suitable habitats in many European countries (16)(17)(18).…”

A novel duplex real-time PCR permits simultaneous detection and differentiation of Borrelia miyamotoi and Borrelia burgdorferi sensu lato

“…In 2013, 834 ticks were collected in the Siebengebirge near Bonn at three neighboring locations typified by their plant community as described earlier [27]. In 2011 and 2012, 553 and 345 I. ricinus, respectively, were collected in the English Garden, Munich, and in 2012 additional 331 in Grafrath, Fürstenfeldbruck, and 60 near Schloss Lustheim, Oberschleißheim, Bavaria.…”

“…2123 ticks were collected in different regions in Germany and 218 in Slovakia by blanket dragging using a cotton flannel [13,27]. In 2013, 834 ticks were collected in the Siebengebirge near Bonn at three neighboring locations typified by their plant community as described earlier [27].…”