Factors Driving the Abundance of Ixodes ricinus Ticks and the Prevalence of Zoonotic I. ricinus-Borne Pathogens in Natural Foci

ABSTRACTEnvironmental factors may drive tick ecology and therefore tick-borne pathogen (TBP) epidemiology, which determines the risk to animals and humans of becoming infected by TBPs. For this reason, the aim of this study was to analyze the influence of environmental factors on the abundance of immature-stageIxodes ricinusticks and on the prevalence of two zoonoticI. ricinus-borne pathogens in natural foci of endemicity.I. ricinusabundance was measured at nine sites in the northern Iberian Peninsula by dragging the vegetation with a cotton flannelette, and ungulate abundance was measured by means of dung counts. In addition to ungulate abundance, data on variables related to spatial location, climate, and soil were gathered from the study sites.I. ricinusadults, nymphs, and larvae were collected from the vegetation, and a representative subsample ofI. ricinusnymphs from each study site was analyzed by PCR for the detection ofBorrelia burgdorferisensu lato andAnaplasma phagocytophilumDNA. Mean prevalences of these pathogens were 4.0% ± 1.8% and 20.5% ± 3.7%, respectively. Statistical analyses confirmed the influence of spatial factors, climate, and ungulate abundance onI. ricinuslarva abundance, while nymph abundance was related only to climate. Interestingly, cattle abundance rather than deer abundance was the main driver ofB. burgdorferisensu lato andA. phagocytophilumprevalence inI. ricinusnymphs in the study sites, where both domestic and wild ungulates coexist. The increasing abundance of cattle seems to increase the risk of other hosts becoming infected byA. phagocytophilum, while reducing the risk of being infected byB. burgdorferisensu lato. Controlling ticks in cattle in areas where they coexist with wild ungulates would be more effective for TBP control than reducing ungulate abundance.

Download Full-text

Nested Species Distribution Models of Chlamydiales in Ixodes ricinus (Tick) Hosts in Switzerland

Applied and Environmental Microbiology ◽

10.1128/aem.01237-20 ◽

2020 ◽

Vol 87 (1) ◽

Author(s):

Estelle Rochat ◽

Séverine Vuilleumier ◽

Sébastien Aeby ◽

Gilbert Greub ◽

Stéphane Joost

Keyword(s):

Environmental Factors ◽

Ixodes Ricinus ◽

Vegetation Index ◽

Respiratory Infections ◽

Smartphone Application ◽

Climatic Conditions ◽

Lower Percentage ◽

Distribution Models ◽

Content Type ◽

Distribution Maps

ABSTRACT The tick Ixodes ricinus is the vector of various pathogens, including Chlamydiales bacteria, which potentially cause respiratory infections. In this study, we modeled the spatial distribution of I. ricinus and associated Chlamydiales over Switzerland from 2009 to 2019. We used a total of 2,293 ticks and 186 Chlamydiales occurrences provided by a Swiss Army field campaign, a collaborative smartphone application, and a prospective campaign. For each tick location, we retrieved from Swiss federal data sets the environmental factors reflecting the topography, climate, and land cover. We then used the Maxent modeling technique to estimate the suitability of particular areas for I. ricinus and to subsequently build the nested niche of Chlamydiales bacteria. Results indicate that I. ricinus habitat suitability is determined by higher temperature and normalized difference vegetation index (NDVI) values, lower temperature during the driest months, and a higher percentage of artificial and forest areas. The performance of the model was improved when extracting the environmental variables for a 100-m radius buffer around the sampling points and when considering the climatic conditions of the 2 years previous to the sampling date. Chlamydiales bacteria were favored by a lower percentage of artificial surfaces, drier conditions, high precipitation during the coldest months, and short distances to wetlands. From 2009 to 2018, we observed an extension of areas suitable to ticks and Chlamydiales, associated with a shift toward higher altitude. The importance of considering spatiotemporal variations in the environmental conditions for obtaining better prediction was also demonstrated. IMPORTANCE Ixodes ricinus is the vector of pathogens including the agent of Lyme disease, the tick-borne encephalitis virus, and the less well-known Chlamydiales bacteria, which are responsible for certain respiratory infections. In this study, we identified the environmental factors influencing the presence of I. ricinus and Chlamydiales in Switzerland and generated maps of their distribution from 2009 to 2018. We found an important expansion of suitable areas for both the tick and the bacteria during the last decade. Results also provided the environmental factors that determine the presence of Chlamydiales within ticks. Distribution maps as generated here are expected to bring valuable information for decision makers in controlling tick-borne diseases in Switzerland and establishing prevention campaigns. The methodological framework presented could be used to predict the distribution and spread of other host-pathogen pairs to identify environmental factors driving their distribution and to develop control or prevention strategies accordingly.

Download Full-text

The role of different species of wild ungulates and Ixodes ricinus ticks in the circulation of genetic variants of Anaplasma phagocytophilum in a forest biotope in north-western Poland

Ticks and Tick-borne Diseases ◽

10.1016/j.ttbdis.2020.101465 ◽

2020 ◽

Vol 11 (5) ◽

pp. 101465

Author(s):

Małgorzata Adamska

Keyword(s):

Ixodes Ricinus ◽

Genetic Variants ◽

Anaplasma Phagocytophilum ◽

Wild Ungulates ◽

Ixodes Ricinus Ticks ◽

North Western

Download Full-text

Influence of environmental factors on the occurrence of Ixodes ricinus ticks in the urban locality of Brno–Pisárky, Czech Republic

Journal of Vector Ecology ◽

10.3376/1081-1710(2007)32[29:ioefot]2.0.co;2 ◽

2007 ◽

Vol 32 (1) ◽

pp. 29-33 ◽

Cited By ~ 7

Author(s):

A. Žákovská ◽

J. Netušil ◽

H. Martiníková

Keyword(s):

Czech Republic ◽

Environmental Factors ◽

Ixodes Ricinus ◽

Ixodes Ricinus Ticks

Download Full-text

Anaplasma phagocytophilum in Questing Ixodes ricinus Ticks: Comparison of Prevalences and Partial 16S rRNA Gene Variants in Urban, Pasture, and Natural Habitats

Applied and Environmental Microbiology ◽

10.1128/aem.03300-12 ◽

2012 ◽

Vol 79 (5) ◽

pp. 1730-1734 ◽

Cited By ~ 16

Author(s):

Evelyn Overzier ◽

Kurt Pfister ◽

Claudia Thiel ◽

Ingrid Herb ◽

Monia Mahling ◽

...

Keyword(s):

16S Rrna ◽

16S Rrna Gene ◽

Ixodes Ricinus ◽

Anaplasma Phagocytophilum ◽

Rrna Gene ◽

Gene Variants ◽

Habitat Types ◽

Natural Habitats ◽

Content Type ◽

Ixodes Ricinus Ticks

ABSTRACTUrban, natural, and pasture areas were investigated for prevalences and 16S rRNA gene variants ofAnaplasma phagocytophilumin questingIxodes ricinusticks. The prevalences differed significantly between habitat types, and year-to-year variations in prevalence and habitat-dependent occurrence of 16S rRNA gene variants were detected.

Download Full-text

Infections and Coinfections of Questing Ixodes ricinus Ticks by Emerging Zoonotic Pathogens in Western Switzerland

Applied and Environmental Microbiology ◽

10.1128/aem.07961-11 ◽

2012 ◽

Vol 78 (13) ◽

pp. 4606-4612 ◽

Cited By ~ 75

Author(s):

Elena Lommano ◽

Luce Bertaiola ◽

Christèle Dupasquier ◽

Lise Gern

Keyword(s):

Ixodes Ricinus ◽

Content Type ◽

Borrelia Lusitaniae ◽

Tick Borne Encephalitis ◽

Rickettsia Monacensis ◽

Questing Ticks ◽

Ixodes Ricinus Ticks ◽

The Subject ◽

Tick Borne Encephalitis Virus ◽

Neoehrlichia Mikurensis

ABSTRACTIn Europe,Ixodes ricinusis the vector of many pathogens of medical and veterinary relevance, among themBorrelia burgdorferisensu lato and tick-borne encephalitis virus, which have been the subject of numerous investigations. Less is known about the occurrence of emerging tick-borne pathogens likeRickettsiaspp.,Babesiaspp., “CandidatusNeoehrlichia mikurensis,” andAnaplasma phagocytophilumin questing ticks. In this study, questing nymph and adultI. ricinusticks were collected at 11 sites located in Western Switzerland. A total of 1,476 ticks were analyzed individually for the simultaneous presence ofB. burgdorferisensu lato,Rickettsiaspp.,Babesiaspp., “CandidatusNeoehrlichia mikurensis,” andA. phagocytophilum. B. burgdorferisensu lato,Rickettsiaspp., and “CandidatusNeoehrlichia mikurensis” were detected in ticks at all sites with global prevalences of 22.5%, 10.2%, and 6.4%, respectively.Babesia- andA. phagocytophilum-infected ticks showed a more restricted geographic distribution, and their prevalences were lower (1.9% and 1.5%, respectively). Species rarely reported in Switzerland, likeBorrelia spielmanii,Borrelia lusitaniae, andRickettsia monacensis, were identified. Infections with more than one pathogenic species, involving mostlyBorreliaspp. andRickettsia helvetica, were detected in 19.6% of infected ticks. Globally, 34.2% of ticks were infected with at least one pathogen. The diversity of tick-borne pathogens detected inI. ricinusin this study and the frequency of coinfections underline the need to take them seriously into consideration when evaluating the risks of infection following a tick bite.

Download Full-text

The High Prevalence and Diversity of Chlamydiales DNA within Ixodes ricinus Ticks Suggest a Role for Ticks as Reservoirs and Vectors of Chlamydia-Related Bacteria

Applied and Environmental Microbiology ◽

10.1128/aem.02183-15 ◽

2015 ◽

Vol 81 (23) ◽

pp. 8177-8182 ◽

Cited By ~ 35

Author(s):

Ludovic Pilloux ◽

Sébastien Aeby ◽

Rahel Gaümann ◽

Caroline Burri ◽

Christian Beuret ◽

...

Keyword(s):

Ixodes Ricinus ◽

Human Pathogens ◽

Content Type ◽

The Family ◽

High Prevalence ◽

Ixodes Ricinus Ticks ◽

Medical Importance ◽

High Level ◽

Positive Results

ABSTRACTTheChlamydialesorder is composed of nine families of strictly intracellular bacteria. Among them,Chlamydia trachomatis,C. pneumoniae, andC. psittaciare established human pathogens, whereasWaddlia chondrophilaandParachlamydia acanthamoebaehave emerged as new pathogens in humans. However, despite their medical importance, their biodiversity and ecology remain to be studied. Even if arthropods and, particularly, ticks are well known to be vectors of numerous infectious agents such as viruses and bacteria, virtually nothing is known about ticks and chlamydia. This study investigated the prevalence ofChlamydiaein ticks. Specifically, 62,889Ixodes ricinusticks, consolidated into 8,534 pools, were sampled in 172 collection sites throughout Switzerland and were investigated using pan-Chlamydialesquantitative PCR (qPCR) for the presence ofChlamydialesDNA. Among the pools, 543 (6.4%) gave positive results and the estimated prevalence in individual ticks was 0.89%. Among those pools with positive results, we obtained 16S rRNA sequences for 359 samples, allowing classification ofChlamydialesDNA at the family level. A high level of biodiversity was observed, since six of the nine families belonging to theChlamydialesorder were detected. Those most common wereParachlamydiaceae(33.1%) andRhabdochlamydiaceae(29.2%). “UnclassifiedChlamydiales” (31.8%) were also often detected. Thanks to the huge amount ofChlamydialesDNA recovered from ticks, this report opens up new perspectives on further work focusing on whole-genome sequencing to increase our knowledge aboutChlamydialesbiodiversity. This report of an epidemiological study also demonstrates the presence ofChlamydia-related bacteria withinIxodes ricinusticks and suggests a role for ticks in the transmission of and as a reservoir for these emerging pathogenicChlamydia-related bacteria.

Download Full-text

TBE in Norway

Tick-borne encephalitis - The Book ◽

10.33442/978-981-14-0914-1_12b-24 ◽

2019 ◽

Author(s):

Katrine M. Paulsen ◽

Rose Vikse ◽

Arnulf Soleng ◽

Kristin S. Edgar ◽

Susanne Dudman ◽

...

Keyword(s):

Ixodes Ricinus ◽

Ixodes Ricinus Ticks

Ixodes ricinus ticks are mainly distributed along the Norwegian coastline from Østfold County in the southeast up approximately to 66°N in Nordland County.

Download Full-text