BackgroundThe bacteria of the group Borrelia burgdorferi s.l. are the etiological agents of Lyme borreliosis in humans, transmitted by bites of ticks. Improvement of control measures requires a solid framework of the environmental traits driving its prevalence in ticks.MethodsWe updated a previous meta-analysis of the reported prevalence of Borrelia burgdorferi s.l. in questing nymphs of Ixodes ricinus with a literature search from January 2010–June 2017. This resulted in 195 new papers providing the prevalence of Bb for 926 geo-referenced records. Previously obtained data (878 records, years 2000–2010) were appended for modelling. The complete dataset contains data from 82,004 questing nymphs, resulting in 558 records of B. afzelii, 404 of B. burgdorferi s.s. (only 80 after the year 2010), 552 of B. garinii, 78 of B. lusitaniae, 61 of B. spielmanii, and 373 of B. valaisiana. We associated the records with explicit coordinates to environmental conditions and to a categorical definition of European landscapes (LANMAP2) looking for a precise definition of the environmental niche of the most reported species of the pathogen, using models based on different classification methods.ResultsThe most commonly reported species are B. afzelii, B. garinii and B. valaisiana largely overlapping across Europe. Prevalence in ticks is associated with portions of the environmental niche. Highest prevalence occurs in areas of 280°–290° (Kelvin) of mean annual temperature experiencing a small amplitude, steady spring slope, together with high mean values and a moderate spring rise of vegetation vigor. Low prevalence occurs in sites with low and a noteworthy annual amplitude of temperature and the Normalized Difference Vegetation Index (colder areas with abrupt annual changes of vegetation). Models based on support vector machines provided a correct classification rate of the habitat and prevalence of 89.5%. These results confirm the association of prevalence of the three most commonly reported species of B. burgdorferi s.l. in Europe to parts of the environmental niche and provide a statistically tractable framework for analyzing trends under scenarios of climate change.Electronic supplementary materialThe online version of this article (10.1186/s12942-018-0163-7) contains supplementary material, which is available to authorized users.

Ticks and tick-borne pathogens are changing their current distribution, presumably due to the impact of the climate trends. On a large scale, these trends are changing the environmental suitability of Hyalomma marginatum, the main vector of several pathogens affecting human health. We generated annual models of environmental suitability for the tick in the period 1970–2018, using harmonic regression-derived data of the daily maximum and minimum temperature, soil moisture and water vapor deficit. The results demonstrate an expansion of the suitable area in Mediterranean countries, southeast central Europe and south of the Balkans. Also, the models allowed us to interpret the impact of the ecological variables on these changes. We deduced that (i) maximum temperature was significant for all of the biogeographical categories, (ii) soil humidity has an influence in the Mediterranean climate areas, and (iii) the minimum temperature and deficit water vapor did not influence the environmental suitability of the species. The conclusions clearly show that climate change could create new areas in Europe with suitable climates for H. marginatum, while keeping its “historical” distribution in the Mediterranean. Therefore, it is necessary to further explore possible risk areas for H. marginatum and its associated pathogens.

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Background: Population of stray dogs is significant in large cities of Nepal, such as Kathmandu. Most of stray dogs suffer a lack of basic health care. Considering the clinical relevance, the broad distribution and the lack of information of canine vector borne diseases (CVBD) in Nepal, the aim of this study was to evaluate the prevalence of different vector-borne pathogens (VBP) in stray dogs living in the metropolitan area of Kathmandu, and to assess different traits as possible risk factors. Methods: A total of 70 canine blood samples from stray dogs attended at the Kathmandu Animal Treatment Centre during August 2017 were collected on filter paper (Flinders Technology Associates (FTA) cards). Data regarding signalment, clinical signs and epidemiological characteristics were recorded for each animal. Real-time polymerase chain reaction assays were performed for Leishmania spp., Ehrlichia spp./Anaplasma spp., Babesia spp./Theileria spp. and Hepatozoon canis. Results: The overall prevalence detected was 31.43% for Hepatozoon canis, 31.43% for Anaplasma platys, 27.14% for Ehrlichia canis, 18.57% for Leishmania donovani species complex, 12.86% for isolates corresponding to Theileria spp., 12.86% for Babesia vogeli and 2.86% for B. gibsoni. A total of 81.43% of the dogs were positive to at least one of the VBP tested. Co-infections were detected in 41.43% of the dogs. Dogs positive to any of the VBP tested, and particularly to E. canis, were older than those that were negative. Conclusions: To our knowledge, this is the first molecular detection of VBP in stray dogs from Kathmandu, Nepal. The high prevalence of VBP detected highlights the need to implement a surveillance programme and control strategies for these CVBD in the population of stray dogs in this area.