A large-scale screening for the taiga tick, Ixodes persulcatus, and the meadow tick, Dermacentor reticulatus, in southern Scandinavia, 2016

Abstract The taiga tick, Ixodes persulcatus, has previously been limited to eastern Europe and northern Asia, but recently its range has expanded to Finland and northern Sweden. The species is of medical importance, as it, along with a string of other pathogens, may carry the Siberian and Far Eastern subtypes of tick-borne encephalitis virus. These subtypes appear to cause more severe disease, with higher fatality rates than the central European subtype. Until recently, the meadow tick, Dermacentor reticulatus, has been absent from Scandinavia, but has now been detected in Denmark, Norway and Sweden. Dermacentor reticulatus carries, along with other pathogens, Babesia canis and Rickettsia r…

Prevalence of tick-borne encephalitis virus in questing Ixodes ricinus nymphs in southern Scandinavia and the possible influence of meteorological factors

Ixodes ricinus ticks are Scandinavia's main vector for tick-borne encephalitis virus (TBEV), which infects many people annually. The aims of the present study were (i) to obtain information on the TBEV prevalence in host-seeking I. ricinus collected within the Øresund-Kattegat-Skagerrak (ØKS) region, which lies in southern Norway, southern Sweden and Denmark; (ii) to analyse whether there are potential spatial patterns in the TBEV prevalence; and (iii) to understand the relationship between TBEV prevalence and meteorological factors in southern Scandinavia. Tick nymphs were collected in 2016, in southern Scandinavia, and screened for TBEV, using pools of 10 nymphs, with RT real-time PCR, an…

Correction to: Detection of Candidatus Neoehrlichia mikurensis in Norway up to the northern limit of Ixodes ricinus distribution using a novel real time PCR test targeting the groEL gene

Candidatus Neoehrlichia mikurensis is an emerging tick-borne pathogen. It is widely distributed in Ixodes ricinus ticks in Europe, but knowledge of its distribution in Norway, where I. ricinus reaches its northern limit, is limited. In this study we have developed a real time PCR test for Ca. N. mikurensis and used it to investigate the distribution of Ca. N. mikurensis in Norway.Real time PCR targeting the groEL gene was developed and shown to be highly sensitive. It was used to detect Ca. N. mikurensis in 1651 I. ricinus nymphs and adults collected from twelve locations in Norway, from the eastern Oslo Fjord in the south to near the Arctic Circle in the north. The overall prevalence was 6…

Prevalence of Borrelia burgdorferi in Ixodes ricinus ticks collected from moose (Alces alces) and roe deer (Capreolus capreolus) in southern Norway

As part of a larger survey, ears from 18 roe deer (Capreolus capreolus) and 52 moose (Alces alces) shot in the 2 southernmost counties in Norway were collected and examined for Ixodes ricinus ticks. Seventy-two adult ticks, 595 nymphs, and 267 larvae from the roe deer, and 182 adult ticks, 433 nymphs, and 70 larvae from the moose were investigated for infection with Borrelia burgdorferi sensu lato (s.l.). The results showed the presence of B. burgdorferi s.l. DNA in 2.9% of the nymphs collected from roe deer and in 4.4% of the nymphs and 6.0% of the adults collected from moose. The spirochetes were not detected in adult ticks from roe deer, or in larvae feeding on roe deer or moose. In comp…

INTERNATIONAL COLLABORATIVE PROJECT ON TICK-BORNE ENCEPHALITIS IN THE BARENTS REGION

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Spatial patterns of pathogen prevalence in questing Ixodes ricinus nymphs in southern Scandinavia

Predicting and mapping human risk of exposure to ixodes ricinus nymphs using climatic and environmental data, Denmark, Norway and Sweden, 2016

Background Tick-borne diseases have become increasingly common in recent decades and present a health problem in many parts of Europe. Control and prevention of these diseases require a better understanding of vector distribution. Aim Our aim was to create a model able to predict the distribution of Ixodes ricinus nymphs in southern Scandinavia and to assess how this relates to risk of human exposure. Methods We measured the presence of I. ricinus tick nymphs at 159 stratified random lowland forest and meadow sites in Denmark, Norway and Sweden by dragging 400 m transects from August to September 2016, representing a total distance of 63.6 km. Using climate and remote sensing environmental…

Prevalence and genotypes of Borrelia burgdorferi sensu lato infection in Ixodes ricinus ticks in southern Norway.

From April to October 2007, host-seeking Ixodes ricinus ticks were collected from 4 locations in southern Norway: Farsund, Mandal, Sogne and Tromoy. Two hundred and ten larvae, 1130 nymphs and 449 adults were investigated for infection with Borrelia burgdorferi sensu lato (s.l.) by real-time polymerase chain reaction (PCR) amplification of the 16S rRNA gene. The total percentage of B. burgdorferi s.l. in nymphal and adult ticks was determined to be 31.3% in Farsund, 25.2% in Mandal, 22.3% in Sogne and 22.1% in Tromoy. Larvae were pooled in groups of 10 before analysis, and Borrelia infection was detected in 1 of the 21 larvae pools. B. burgdorferi s.l. were genotyped by melting curve analys…

Predicting the spatial abundance of Ixodes ricinus ticks in southern Scandinavia using environmental and climatic data

AbstractRecently, focus on tick-borne diseases has increased as ticks and their pathogens have become widespread and represent a health problem in Europe. Understanding the epidemiology of tick-borne infections requires the ability to predict and map tick abundance. We measured Ixodes ricinus abundance at 159 sites in southern Scandinavia from August-September, 2016. We used field data and environmental variables to develop predictive abundance models using machine learning algorithms, and also tested these models on 2017 data. Larva and nymph abundance models had relatively high predictive power (normalized RMSE from 0.65–0.69, R2 from 0.52–0.58) whereas adult tick models performed poorly …

Detection of Candidatus Neoehrlichia mikurensis in Norway up to the northern limit of Ixodes ricinus distribution using a novel real time PCR test targeting the groEL gene

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Background Candidatus Neoehrlichia mikurensis is an emerging tick-borne pathogen. It is widely distributed in Ixodes ricinus ticks in Europe, but knowledge of its distribution in Norway, where I. ricinus reaches its northern limit, is limited. In this study we have developed a real time PCR test for Ca. N. mikurensis and used it to invest…

Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from migratory birds in Southern Norway

Abstract Background Borrelia burgdorferi sensu lato (s.l.) are the causative agent for Lyme borreliosis (LB), the most common tick-borne disease in the northern hemisphere. Birds are considered important in the global dispersal of ticks and tick-borne pathogens through their migration. The present study is the first description of B. burgdorferi prevalence and genotypes in Ixodes ricinus ticks feeding on birds during spring and autumn migration in Norway. Methods 6538 migratory birds were captured and examined for ticks at Lista Bird Observatory during the spring and the autumn migration in 2008. 822 immature I. ricinus ticks were collected from 215 infested birds. Ticks were investigated f…

Spatial data of Ixodes ricinus instar abundance and nymph pathogen prevalence, Scandinavia, 2016-2017.

ticks carry pathogens that can cause disease in both animals and humans, and there is a need to monitor the distribution and abundance of ticks and the pathogens they carry to pinpoint potential high risk areas for tick-borne disease transmission. In a joint Scandinavian study, we measured Ixodes ricinus instar abundance at 159 sites in southern Scandinavia in August-September, 2016, and collected 29,440 tick nymphs at 50 of these sites. We additionally measured abundance at 30 sites in August-September, 2017. We tested the 29,440 tick nymphs in pools of 10 in a Fluidigm real-time PCR chip to screen for 17 different tick-associated pathogens, 2 pathogen groups and 3 tick species. We present…

Tick-borne encephalitis virus, Borrelia burgdorferi sensu lato, Borrelia miyamotoi, Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis in Ixodes ricinus ticks collected from recreational islands in southern Norway

The aim of this study was to determine the occurrence of tick-borne pathogens of medical importance in questing ticks collected from five recreationally used islands along the Norwegian coastline. Furthermore, since coinfection may affect the disease severity, this study aimed to determine the extent of coinfection in individual ticks or co-localization of tick-borne pathogens. In all, 4158 questing Ixodes ricinus ticks were analyzed. For detection of tick-borne encephalitis virus (TBEV), nymphs (3690) were analyzed in pools of ten. To detect Borrelia burgdorferi sensu lato, B. miyamotoi, Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis, 468 nymphs were analyzed individually…

BORRELIA BURGDORFERI SENSU LATO DETECTED IN SKIN OF NORWEGIAN MOUNTAIN HARES (LEPUS TIMIDUS) WITHOUT SIGNS OF DISSEMINATION

The mountain hare (Lepus timidus) population in southern Norway appears to be in decline. Necropsy and laboratory examinations of 36 hares found dead or diseased during 2007-2009 in Vest- and Aust-Agder counties showed that disease and deaths were attributed to multiple causes, with no specific etiology emerging as a cause for population decline. To investigate whether Borrelia burgdorferi sensu lato (s.l.) infection is associated with mortality in mountain hares, tissues and ticks collected from hares were investigated for infection with the spirochete. Borrelia burgdorferi s.l. DNA was not detected in samples from internal organs, whereas Borrelia afzelii, B. burgdorferi sensu stricto (s.…