Dermacentor reticulatus - a tick on its way from glacial refugia to a panmictic Eurasian population.

The ornate dog tick (Dermacentor reticulatus) shows a recently expanding geographic distribution. Knowledge on its intraspecific variability, population structure, rate of genetic diversity and divergence, including its evolution and geographic distribution, is crucial to understand its dispersal capacity. All such information would help to evaluate the potential risk of future spread of associated pathogens of medical and veterinary concern. A set of 865 D. reticulatus ticks was collected from 65 localities across 21 countries, from Portugal in the west to Kazakhstan and southern Russia in the east. Cluster analyses of 16 microsatellite loci were combined with nuclear (ITS2, 18S) and mitochondrial (12S, 16S, COI) sequence data to uncover the ticks' population structures and geographical patterns. Approximate Bayesian computation was applied to model evolutionary relationships among the found clusters. Low variability and a weak phylogenetic signal showing an east-west cline were detected both for mitochondrial and nuclear sequence markers. Microsatellite analyses revealed three genetic clusters, where the eastern and western cluster gradient was supplemented by a third, northern cluster. Alternative scenarios could explain such a tripartite population structure by independent formation of clusters in separate refugia, limited gene flow connected with isolation by distance causing a "bipolar pattern", and the northern cluster deriving from admixture between the eastern and western populations. The best supported demographic scenario of this tick species indicates that the northern cluster derived from admixture between the eastern and western populations 441 (median) to 224 (mode) generations ago, suggesting a possible link with the end of the Little Ice Age in Europe.

Update on prevalence of Babesia canis and Rickettsia spp. in adult and juvenile Dermacentor reticulatus ticks in the area of Poland (2016-2018).

Ornate dog tick, Dermacentor reticulatus is an important vector of Babesia canis, and Rickettsia spp. and other pathogens of veterinary and public health interest. The current study is the first to investigate the long-term changes in prevalence of these pathogens in expanding tick populations in Central Europe. Molecular techniques (PCR, sequencing) were applied for the detection of pathogen DNA in adult (n = 2497) and juvenile ticks (1096 larvae and 410 nymphs). DNA of Rickettsia spp. was identified in 35% of adults and 12.6% of juvenile ticks. DNA of B. canis was detected in 3% of adult ticks and only in ticks from the Eastern region (regional prevalence 6%). As previously, no B. canis-positive ticks were found in Western Poland, including ticks from Wroclaw area (n = 298). DNA of B. canis was identified in 0.33% of juvenile ticks (in 3 pools of larvae and 2 nymphs) from the Eastern region. In the current study we confirmed high occurrence of R. raoultii in adults ticks from all four zones and relatively high prevalence of B. canis in the Eastern population of D. reticulatus, corresponding well with high incidence of canine babesiosis in this area of Poland. Finally, we confirmed R. raoultii and B. canis infection in all life stages of D. reticulatus ticks.

The local-scale expansion of Dermacentor reticulatus ticks in Lower Silesia, SW Poland.

The range of D. reticulatus is discontinuous in Europe, with a gap between the Western and Eastern European populations. Recent studies have shown, however, a decrease in the gap as a consequence of D. reticulatus spreading to new areas. This study aims to analyze the dynamic of local-scale changes in the D. reticulatus range in Lower Silesia, SW Poland. All sites of D. reticulatus presence recognized in our research were located in the north-western part of the study area (Wroclaw and its surroundings), whereas the south-eastern part was found to be free of these ticks. However, a five-year observation period (2014-2019) indicates the expansion of D. reticulatus on a local scale, with a general tendency to expand to the east, with northerly or southerly deviations from year to year. The settled sites differed in distance to the nearest built-up area, the density of resident population, as well as land development intensity in the immediate vicinity. The 100% probability isolines of D. reticulatus presence in Wroclaw and its surroundings allowed the determination of the rate of range change, which turned out to be uneven in terms of direction and speed. The average rate of change in the range of tick occurrence was estimated at 7 km in 3 years. A more accurate analysis of the estimated range changes-made using modeling and verification of predicted changes in the field-showed that the likely rate of range change can be estimated at around 0.6-2.3 km/year.

First record of Haemaphysalis concinna (Acari: Ixodidae) in Lower Silesia, SW Poland.

Haemaphysalis concinna Koch is one of 19 species of the genus Haemaphysalis which has been reported in the Palearctic region. In Europe, the presence of H. concinna ticks has been reported in numerous countries. In Poland, to date, the precise occurrence of H. concinna was known only from one site in the north-western region. This paper shows that H. concinna ticks can be considered a typical example of the tick fauna occurring in Lower Silesia, SW Poland. Tick monitoring was conducted using a standard flagging method in 24 sites in the various forest types of Lower Silesia. Among 1622 host-seeking ticks collected, H. concinna accounted for 2.7%. From the collected H. concinna there were: 25 (58.1%) larvae, 15 (34.9%) nymphs, 1 (2.3%) female, and 2 (4.7%) males. The presence of H. concinna was confirmed in 6 out of 24 tested sites in fresh mixed broadleaf forests, fresh mixed coniferous forests and in pastures.

Seroprevalence of Borrelia burgdorferi in forest workers from inspectorates with different forest types in Lower Silesia, SW Poland: preliminary study.

To estimate the Lyme borreliosis (LB) risk for forest workers, totally 646 blood samples were tested for IgG and IgM anti-Borrelia burgdorferi s.l. (anti-B.b.) antibody occurrence using ELISA tests confirmed with western blot. To clarify the varied LB risk, additionally, the data from the Forest Data Bank determining the detailed forest habitat type in particular forest inspectorates were used. The occurrence of the anti-B.b. antibody was confirmed in 22% (8.7% IgM, 17.8% IgG) of forest workers. Analysis of the influence of the habitat type (forest types) indicated the significant positive impact of the occurrence of the deciduous and mixed-deciduous forests on the seroprevalence of anti-B.b. IgG level among forestry workers. However, the share of forest type cannot be the only factor taken into account when assessing risk.

Winter activity of Dermacentor reticulatus (Fabricius, 1794) in the newly emerging population of Lower Silesia, south-west Poland.

This paper presents the unexpected winter activity of Dermacentor reticulatus (Fabricius, 1794) ticks in a newly emerging population in south-west Poland. Host-seeking ticks were collected from vegetation in January 2016 in a meadow ecosystem in six sites located in the Wroclaw Agglomeration, as well as from ten companion animals. A total of 238 questing D. reticulatus ticks, comprising 166 females and 72 males, were collected from all examined sites with the highest number of 102 specimens collected in one hour in one locality (Muchobór Wielki, Wroclaw). Additionally, two fully-engorged females were collected from two dogs along with one slightly engorged female from a cat. The fact that D. reticulatus can be very active in January indicates a need to take into account the increased threat of tick-bite in the winter time.

The prevalence of Anaplasma phagocytophilum in questing Ixodes ricinus ticks in SW Poland.

Ticks constitute important vectors of human and animal pathogens. Besides the Lyme borreliosis and tick-borne encephalitis, other pathogens such as Babesia spp., Rickettsia spp., and Anaplasma phagocytophilum, are of increasing public health interest. In Poland, as in other European countries, Ixodes ricinus, the most prevalent tick species responsible for the majority of tick bites in humans, is the main vector of A. phagocytophilum. The aim of the study was to estimate the infection level of I. ricinus with A. phagocytophilum in selected districts, not previously surveyed for the presence of this agent. Sampling of questing ticks was performed in 12 forested sites, located in four districts (Legnica, Milicz, Luban, and Olawa) in SW Poland. Altogether, 792 ticks (151 females, 101 males, and 540 nymphs) representing I. ricinus were checked for the presence of A. phagocytophilum. The average infection level was 4.3%, with higher rate reported for adult ticks. The highest percentage of infected adults was observed in Milicz (17.4%) and the lowest in Olawa (6.8%). The abundance of questing I. ricinus in all examined sites as well as the infection with A. phagocytophilum indicate for the first time the risk for HGA transmission in SW Poland.

Evidence for an increased distribution range of Dermacentor reticulatus in south-west Poland.

The expansion of Dermacentor reticulatus to new geographical areas has been observed in several countries in Europe, including Poland and it's neighbors. In 2011 and 2012, a total of 148 host-seeking D. reticulatus ticks were collected after flagging the vegetation in Lower Silesia, south-western Poland. Tick monitoring was conducted in mixed and deciduous forest, on meadows, in river valleys and ecotones between forested and grassy areas. The ornate dog ticks were found in 10 out of 33 sites located in five districts: Legnica, Wroclaw, Sroda Slaska, Lubin and Boleslawiec County. All sites where D. reticulatus ticks were found are located to the south-west of the Odra River. The greatest distance between these disconnected localities was approximately 90 km. It seems that at present the southern boundary of the range is Wroclaw district. This study indicates that D. reticulatus can be ranked as a typical element of the fauna in Lower Silesia in southwestern Poland.