Analysis of the environmental and host-related factors affecting the distribution of the tick Dermacentor marginatus.

Understanding and responding to the ecological, social and economic conditions that facilitate disease emergence and transmission represents a substantial challenge for epidemiologists and health professionals. In this article we integrate knowledge about the human and the vector population, to provide a context from which to examine the underlying causal factors of D. marginatus-borne diseases emergence in the study area. Within this framework we analyse the biotic and abiotic factors that drive D. marginatus population dynamics and the role of its typical host for dispersal. These investigations suggest that D. marginatus is a tick species prone to spatially overlap its presence with human population presence. Then we consider the public health implications for the residents, when simply carrying out trivial outdoor activities may increase the risk to contact an infected tick.

Habitat and occurrence of ixodid ticks in the Liguria region, northwest Italy.

Questing ticks were collected during monthly dragging sessions (March-August 2011) in three provinces of the Liguria region, north-western Italy, to evaluate the species occurrence, spatial distribution and relative abundance. A total of 1,464 specimens were collected in 94 dragging sites. Ixodes ricinus was the most abundant species (81.3 % of collected ticks), followed by Haemaphysalis punctata (10.9 %), Dermacentor marginatus (5.5 %), Ixodes frontalis (1.3 %), and Rhipicephalus spp. (0.9 %). Ixodes frontalis is reported for the first time in Liguria. An aggregation of I. ricinus positive sites was observed in inland areas characterized by dense forests dominated by deciduous trees (Castanetum and Fagetum phytoclimatic zones), especially in the west of the region where the differences in the Normalized Difference Vegetation Index (NDVI) were higher between inland and coastal sites. Random-effect logistic regression was used to model the associations of NDVI and season with the probability of finding host-seeking I. ricinus nymphs [corrected]. The NDVI was a good predictor of I. ricinus nymphs abundance, and confirmed its utility in discriminating habitat suitability for this vector in north-western coastal Italy, where dry habitat conditions may limit the distribution of this species.