Dorota Kiewra

Ixodes ricinus ticks (Acari, Ixodidae) as a vector of Borrelia burgdorferi sensu lato and Borrelia miyamotoi in Lower Silesia, Poland – Preliminary study

Ixodes ricinus is the primary vector of Borrelia spirochetes in Europe, including both the Lyme borreliosis (LB) group and the relapsing fever (RF) group. The aim of the study was to estimate the prevalence of different genospecies from the B. burgdorferi s.l. complex and B. miyamotoi in questing I. ricinus collected in chosen areas in Lower Silesia, SW Poland. A total of 599 I. ricinus ticks were investigated using the PCR-RFLP method. The calculated overall minimum infection rate of ticks with Borrelia spirochetes in Lower Silesia was 15.5%. Five different restriction patterns, characteristic of B. afzelii, B. garinii, B. burgdoreri s.s., B. valaisiana, and B. miyamotoi, were obtained and confirmed by DNA sequencing. At least 14% of ticks were infected with B. burgdorferi s.l. while B.afzelii was the dominant genospecies (68.5%). The MIR for B. miyamotoi was calculated at 2%. Four co-infections in single adult ticks were found: B. miyamotoi/B. afzelii, B. miyamotoi/B. burdorferi s.s., B. miyamotoi/B. garinii, and B. afzelii/B. burgdorferi s.s. The results of this study confirm the risk of LB and RF occuring in both urban and protected areas.

Evaluation of Three Microbial Formulations Against Culex pipiens pipiens Larvae in Irrigation Fields in Wroclaw, Poland

Abstract Two evaluations of microbial mosquito larvicides were conducted in irrigation fields located along the Odra River near the city of Wroclaw, Poland. In the first evaluation, 3 dosages each of Bacillus thuringiensis israelensis (Bti)—VectoBac® water dispersible granule (WDG) and VectoBac aqueous suspension formulation (12AS)—and Bacillus sphaericus (Bs)—VectoLex® WDG—were tested against larvae of Culex pipiens pipiens. There was little difference between formulations and rates of application between day 2 and 7 following the treatment. VectoBac WDG at 300 g/ha resulted in 100% mortality of Cx. p. pipiens. Between 0.5 and 1 liter of VectoBac 12AS caused sufficient mortality for up to 7 days. The effective short-term application rate of VectoLex WDG was found to be 400 g/ha. The above doses can be recommended for up to 7-day control in this habitat. In the second evaluation, using VectoBac WDG at 800 g/ha, the residual efficacies of 2 ground application methods, a knapsack sprayer configured for large droplet application and a motorized backpack blower configured for small droplet application, were compared. The results indicated no significant difference between the 2 application methods, but a significant long-term effect of VectoBac WDG was observed at the rate of 800 g/ha.

Influence of Selected Meteorological Variables on the Questing Activity of Ixodes ricinus Ticks in Lower Silesia, SW Poland

ABSTRACT: The relationship between climate data and tick questing activity is crucial for estimation of the spatial and temporal distribution of the risk of ticks and tick-borne diseases. This study establishes correlations between selected meteorological variables provided by the Weather Research and Forecasting model (WRF) and the questing activity of Ixodes ricinus nymphs and adults on a regional scale across Lower Silesia, Poland. Application of Generalized Linear Mixed Models (GLMM), built separately for adults and nymphs, showed that solar radiation, air temperature, and saturation deficit appeared to be the meteorological variables of prime importance, whereas the wind speed was less important. However, the effect of meteorological parameters was different for adults and nymphs. The adults are also more influenced by forest cover and the percentage of forest type if compared to nymphs. The WRF model providing meteorological variables separately for each location and day of tick sampling can be useful in studies of questing activity of ticks on a regional scale.

The role of domestic dogs and cats in the zoonotic cycles of ticks and pathogens. Preliminary studies in the Wroclaw Agglomeration (SW Poland).

The collection of 729 tick specimens (Ixodes ricinus, 88.6%; Ixodes hexagonus, 9.2%; Dermacentor reticulatus, 2.2%) removed from 373 dogs and 78 cats, along with 201 ticks from vegetation (I. ricinus, 75.6%; D. reticulatus, 24.4%), allows one to say that pets play an important role in maintaining tick life cycles in different urban area. It shows the lack of statistical differences between tick intensity in high-impact anthropogenic areas (HIAA), low-impact anthropogenic areas (LIAA) and mixed areas designed, in an objective way, by GIS techniques. The comparable (statistically insignificant) level of infection with Borrelia spp. of I. ricinus from pets (22.5%) and vegetation (24.8%), shows that dogs and cats do not have zooprophylactic competence for Borrelia spp. in different urban areas. Moreover, Borrelia spp. was detected in I. hexagonues (1.5%) collected from pets, and in D. reticulatus (2%) obtained from vegetation. The presence of D. reticulatus in the Wrocław Agglomeration confirms its expansion and the distribution range in Poland.

Relationship between Temporal Abundance of Ticks and Incidence of Lyme Borreliosis in Lower Silesia Regions of Poland

ABSTRACT: The aim of this study was to identify the factors determining the incidence of Lyme borreliosis (LB) in southwestern Poland by estimating the prevalence of B. burgdorferi s. 1. in I. ricinus, and to analyze the temporal abundance of ticks in relation to epidemiological data on LB incidence. Host-seeking ticks collected in 2011 in four districts in southwestern Poland were examined by nested PCR for the presence of B. burgdorferi s.l. In total, 2,507 host-seeking I. ricinus were collected. The temporal abundance of ticks varied between districts. The minimal infection rates with B. burgdorferi s.l. were 11.5% for nymphs and 37.7% for adults. There were no statistical differences in the level of infection between districts either for nymphs or for adults. Five different genospecies were identified within the B. burgdorferi s.l. complex: B. garinii, B. afzelii, B. lusitaniae, B. valasiana, and B. burgdorferi s.s., and additionally B. miyamotoi. Our results point to a relationship between tick temporal abundance and LB incidence both for adults and nymphs. The high abundance of ticks is positively correlated with the number of LB cases in humans. The ticks abundance may be considered as a major factor in determining the LB risk in southwestern Poland.

Biometrical analysis of the common tick, Ixodes ricinus, in the Ślęża Massif (Lower Silesia, Poland)

ABSTRACT The aim of this study was to biometrically analyze the behavioral activity of Ixodes ricinus ticks as influenced by season and trend in numbers, based on material collected during three years in the Ślęża Landscape Park within the Ślęża Massif (Lower Silesia, Poland) using a time series decomposition method. The effects of the abiotic factors of air temperature and humidity on this activity were also determined. A total of 2,745 nymphs and adults of I. ricinus was observed and collected from 2001 through 2003. It was the only collected species from the 17 representatives of the family Ixodidae recorded from Poland. The abundance of the common tick in the Ślęża Landscape Park confirms the risk of tickborne diseases in these nature areas that are under legal protection. The chance of being bitten by ticks increases in the spring and autumn when the behavioral activity of these arthropods reaches their highest levels. Predictions concerning the level of tick behavioral activity should take into account not only seasonality but also the effects of random components, which accounted for about half of the tick activity in our study. The method of time series decomposition employed in our research appears to be useful in making such prognoses. Humidity is particularly significant as it can determine the activity of I. ricinus to a large extent.

Local-scale spatio-temporal distribution of questing Ixodes ricinus L. (Acari: Ixodidae)-A case study from a riparian urban forest in Wrocław, SW Poland

This paper presents the distribution of questing Ixodes ricinus ticks in suburban forest intensively visited by people. The local-scale observations conducted during a 4-year study at 99 plots (of 100m2 each) located throughout the entire area of a riparian urban forest, showed a high variation in the density of ticks from year to year. Although I. ricinus is generally permanent in the study area, spatial distribution of sample plots harbouring I. ricinus is variable, i.e. mainly random for adults and larvae, and random or clustered for nymphs. Among the most common plant species in the herb layer, there were not any species which had a statistically significant and constant impact on the occurrence of any of the development stages of I. ricinus. Also relations between the density of tick development stages and vegetation variables, including cover of the herb layer, total species number, species number of the herb layer, and percentage coverage of particular species, as well as ecological indices for light, soil moisture, reaction, and nutrients, did not show any constant and predictable pattern in subsequent years of the study. Only tree and shrub layers were found as variables positively affecting the density of ticks. Although small, suburban forests can be considered as tick-borne risk areas, it is impossible to determine in details areas of tick-borne risk.

Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to Bacillus thuringiensis isolates: preliminary study

Bacillus thuringiensis is a highly specific entomopathogenic microorganism. Although defined as having properties which work against insects, its role in the control of tick populations is still insufficiently known. In our bioassay, four environmental strains of B. thuringiensis, along with one commercially available product (Vectobac), have been used against ticks. Vectobac turned out to be ineffective in the biocontrol of ticks; however, two of environmental B. thuringiensis strains proved to be efficient against both Ixodes ricinus and Dermacentor reticulatus. In those cases, the mortality rate for ticks was assessed as being up to 80%, and LC50 ranged between 9.1 × 106 and 1.3 × 1015 (cfu/ml). Dermacentor reticulatus males were the most sensitive to bacteria. The similarity between the most and least efficient B. thuringiensis strains in enzymatic profiles—including lipases, phosphatases, proteases, and chitinases—may indicate a limited role of detected enzymes in the pathogenicity profile of bacterial strains against ticks.

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

ABSTRACT 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, Wrocław). 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.