Multiple independent transmission cycles of a tick-borne pathogen within a local host community

Many pathogens are maintained by multiple host species and involve multiple strains with potentially different phenotypic characteristics. Disentangling transmission patterns in such systems is often challenging, yet investigating how different host species contribute to transmission is crucial to properly assess and manage disease risk. We aim to reveal transmission cycles of bacteria within the Borrelia burgdorferi species complex, which include Lyme disease agents. We characterized Borrelia genotypes found in 488 infected Ixodes ricinus nymphs collected in the Sénart Forest located near Paris (France). These genotypes were compared to those observed in three sympatric species of small mammals and network analyses reveal four independent transmission cycles. Statistical modelling shows that two cycles involving chipmunks, an introduced species, and non-sampled host species such as birds, are responsible for the majority of tick infections. In contrast, the cycle involving native bank voles only accounts for a small proportion of infected ticks. Genotypes associated with the two primary transmission cycles were isolated from Lyme disease patients, confirming the epidemiological threat posed by these strains. Our work demonstrates that combining high-throughput sequence typing with networks tools and statistical modeling is a promising approach for characterizing transmission cycles of multi-host pathogens in complex ecological settings

Molecular assessment of Theileria equi and Babesia caballi prevalence in horses and ticks on horses in southeastern France

International audienceEquine piroplasmosis (EP) is a tick-borne disease caused by Babesia caballi and Theileria equi that is potentially emerging in non-endemic countries. We conducted a descriptive study to investigate EP prevalence and spatial distribution in an endemic region: the Camargue and the Plain of La Crau in France. In spring 2015 and 2016, we carried out sampling at stables (total n = 46) with a history of horses presenting chronic fever or weight loss. Overall, we collected blood from 632 horses, which were also inspected for ticks; these horses had been housed in the target stables for at least 1 year. We obtained 585 ticks from these horses and described land use around the stables. Real-time PCR was employed to assess T. equi and B. caballi prevalence in the horses and in the ticks found on the horses. For the horses, T. equi and B. caballi prevalence was 68.6% and 6.3%, respectively. For the ticks found on the horses, prevalence was 28.8% for T. equi and 0.85% for B. caballi. The most common tick species were, in order of frequency, Rhipicephalus bursa , R. sanguineus sl. , Hyalomma marginatum , Haemaphysalis punctata , and Dermacentor sp. Horses bearing Rhipicephalus ticks occurred in wetter zones, closer to agricultural areas, permanent crops, and ditches, as well as in drier zones, in the more northern countryside. Compared to horses bearing R. bursa , horses bearing R. sanguineus sl. more frequently occurred near the Rhone River. Prevalence of T. equi in the ticks was as follows: Hyalomma marginatum (43%), Dermacentor sp. (40%), R. bursa (33%), R. sanguineus sl. (19%), and Haemaphysalis punctata (17%). In contrast, B. caballi only occurred in Dermacentor sp. (20%) and R. bursa (1%)

Is sacral nerve modulation reprogramming effective after permanent implantation for faecal incontinence?

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Distribution of ticks, tick-borne pathogens and the associated local environmental factors including small mammals and livestock, in two French agricultural sites: the OSCAR database

International audienceBackground: In Europe, ticks are major vectors of both human and livestock pathogens (e.g. Lyme disease, granulocytic anaplasmosis, bovine babesiosis). Agricultural landscapes, where animal breeding is a major activity, constitute a mosaic of habitat types of various quality for tick survival and are used at different frequencies by wild and domestic hosts across seasons. This habitat heterogeneity, in time and space, conditions the dynamics of these host-vector-pathogen systems and thus drives acarological risk (defined as the density of infected ticks). The principal objective of the OSCAR project (2011-2016) was to examine the links between this heterogeneity and acarological risk for humans and their domestic animals. Here, we present the data associated with this project.New information This paper reports a database on the distribution and densities of I. ricinus ticks-the most common tick species in French agricultural landscapes-and the prevalence of three tick-borne pathogens (Anaplasma phagocytophilum, Borrelia spp. and Babesia spp.) in two sites in north-western ("Zone Atelier Armorique" ZA site) and south-western ("Vallees et Coteaux de Gascogne" VG site) France. The distribution and density of ticks along a gradient of wooded habitats, as well as biotic variables, such as the presence and abundance of their principal domestic (livestock) and wild hosts (small mammals), were measured from forest cores and edges to more or less isolated hedges, all bordering meadows. Ticks, small mammals and information on local environmental conditions were collected along 90 transects in each of the two sites in spring and autumn 2012 and 2013 and in spring 2014, corresponding to the main periods of tick activity. Local environmental conditions were recorded along each tick and small mammal transect habitat type, vegetation type and characteristics, slope and traces of livestock presence. Samples consisted of questing ticks collected on the vegetation (mainly I. ricinus nymphs), biopsies of captured small mammals and ticks fixed on small mammals. In the VG site, livestock occurrence and abundance were recorded each week along each tick transect. A total of 29004 questing ticks and 1230 small mammals were captured during the study across the two sites and over the five field campaigns. All questing nymphs (N = 12287) and questing adults (N = 646) were identified to species. Ticks from small mammals (N = 1359) were also identified to life stage. Questing nymphs (N = 4518 I. ricinus) and trapped small mammals (N = 908) were analysed for three pathogenic agents A. phagocytophilum, Borrelia spp. and Babesia spp. In the VG site, the average prevalence in I. ricinus nymphs for A. phagocytophilum, Borrelia spp. and Babesia spp. were, respectively 1.9% [95% CI 1.2-2.5], 2.5% [95% CI 1.8-3.2] and 2.7% [95% CI 2.0-3.4]. In small mammals, no A. phagocytophilum was detected, but the prevalence for Borrelia spp. was 4.2% [95% CI 0.9-7.5]. On this site, there was no screening of small mammals for Babesia spp. In ZA site, the average prevalence in nymphs for A. phagocytophilum, Borrelia spp. and Babesia were, respectively 2.2% [95% CI 1.6-2.7], 3.0% [95% CI 2.3-3.6] and 3.1% [95% CI 2.5-3.8]. In small mammals, the prevalence of A. phagocytophilum and Borrelia spp. were, respectively 6.9% [95% CI 4.9-8.9] and 4.1% [95% CI 2.7-5.9]. A single animal was found positive for Babesia microti at this site amongst the 597 tested

Risk assessment associated with ticks in urban and periurban green spaces in the region of Lyon, France: Results of ticks and rodents surveillance from 2019 to 2022

International audienceIn Europe, ticks can transmit many zoonotic pathogens to humans including bacteria of the Borrelia Burgdorferi (s.l.) complex responsible for Lyme borreliosis (LB). In the Auvergne Rhône-Alpes region (southeastern France), the incidence rate of LB was estimated 156 cases per 100,000 inhabitants. While the risk of exposure to tick bites is well known in forests and rural areas, it remains unclear in urban and peri-urban green spaces, which are however very frequented by human beings.Two urban parks and one peri-urban park were subject to acarological surveillance from 2019 to 2022 using the dragging method. A rural site was used as control. In each park, one hundred 10 m2 transects were chosen at random in closed (forests, woods), intermediate (edges) and open (lawns, meadows) environments. From 2020 to 2022, rodents were also captured with traps twice a year in one urban and one periurban park in the context of the BioRodDis BiodivERsA project. Ticks were stored in 70% ethanol for subsequent morphological identification. DNA extracted from ticks and ears from rodents and were screened for Borrelia burgdorferi sl by qPCR. In 2021 and 2022, new sites distributed along a western, northern ans southern ecological corridors from the outskirts to the center of the city were also monitored for ticks.The acarological surveillance confirms the presence of Ixodes ricinus ticks in urban and periurban sites respectively with significantly higher abundances in periurban green spaces. It shows that areas under forest cover and forest edges are the most at risk of tick exposure. Molecular analyses detected bacteria of the Borrelia burgdorferi sl complex in ticks in almost all periurban green space. Only one tick was found infected in the urban environments explored. Similar tendencies were obtained for prevalences in rodents.The study suggests that the risk of Ixodes ricinus and Borrelia burgdorferi sl exposure is possible even in the urban area but significantly lower than in peri-urban and rural environments. The surveillance should be extended to other sites, animals and humans to improve knowledge on risk exposure to ticks and determine drivers for ticks presence and abundance in urbanized environments

Where to find questing Ixodes frontalis ticks? Under bamboo bushes!

International audienceseveral species of vertebrate hosts, vectors and pathogens. While most studies in Europe are focused on Ixodesricinus, other Ixodes species may also be involved in the transmission or maintenance of pathogens. This is thecase of Ixodes frontalis, a poorly known species associated with different bird species such as blackbirds, thrushesand robins, with a wide distribution covering most European countries.In a previous study, high densities of questing I. frontalis larvae were found during autumn-winter at a siteclose to Nantes (western France) where a long-term survey focused on I. ricinus was conducted. These I. frontaliswere mostly observed under bamboo bushes. In the present study, we investigated the presence of I. frontalisunder bamboo bushes at various locations. With that aim in mind, a systematic search for questing I. frontalis wasundertaken by the flagging method in public urban parks and private gardens presenting bamboo bushes (32sites). This survey was carried out during autumn-winter to maximize the probability of finding the mostabundant stage, i.e. larvae. We searched for I. frontalis first in the area of Nantes (10 sites), then in other regionsof France (21 sites) and at one site in northern Italy. A single visit to each site revealed the presence of I. frontalisat 29 out of 32 sites: larvae were always present, nymphs were frequent (59 % of the positive sites), while adultswere found at only 14 % of the sites. Questing stages of this understudied species are thus easy to find, bydragging or flagging under bamboo bushes in autumn or winter. We make the assumption that bamboo offers afavourable place for birds to roost overnight outside their breeding period (i.e. spring), sheltered from bothpredators and wind. This would explain higher densities of I. frontalis under bamboo, relative to other biotopes.As I. frontalis is known to harbour zoonotic pathogens, the consequences of this discovery on the epidemiologyof tick-borne diseases are discussed

Seasonality of host-seeking Ixodes ricinus nymph abundance in relation to climate

There is growing concern about climate change and its impact on human health. Specifically, global warming could increase the probability of emerging infectious diseases, notably because of changes in the geographical and seasonal distributions of disease vectors such as mosquitoes and ticks. For example, the range of Ixodes ricinus, the most common and widespread tick species in Europe, is currently expanding northward and at higher altitudes. However, little is known about the seasonal variation in tick abundance in different climates. Seasonality of I. ricinus is often based on expert opinions while field surveys are usually limited in time. Our objective was to describe seasonal variations in I. ricinus abundance under different climates. To this end, a seven-year longitudinal study, with monthly collections of I. ricinus host-seeking nymphs, was carried out in France, in six locations corresponding to different climates. Tick data were log-transformed and grouped between years so as to obtain seasonal variations for a typical year. Daily average temperature was measured during the study period. Seasonal patterns of nymph abundance were established for the six different locations using linear harmonic regression. Model parameters were estimated separately for each location. Seasonal patterns appeared different depending on the climate considered. Western temperate sites showed an early spring peak, a summer minimum and a moderate autumn and winter abundance. More continental sites showed a later peak in spring, and a minimum in winter. The peak occurred in summer for the mountainous site, with an absence of ticks in winter. In all cases except the mountainous site, the timing of the spring peak could be related to the sum of degree days since the beginning of the year. Winter abundance was positively correlated to the corresponding temperature. Our results highlight clear patterns in the different sites corresponding to different climates, which allow further forecast of tick seasonality under changing climate conditions

Le projet Oscar : prendre en compte l'hétérogénéité spatiale du paysage pour comprendre les déterminants de la distribution du risque lié aux maladies à tiques

International audienceLes tiques sont des vecteurs majeurs de maladies à la fois animales et humaines (la plupart étant zoonotiques) et dans l'hémisphère nord, elles sont considérées comme les vecteurs les plus importants en santé humaine en raison notamment de la maladie de lyme. Même si l'espèce la plus fréquente en Europe - Ixodes ricinus - est d'abord forestière en raison de l'hygrométrie importante qu'elle exige, on la retrouve cependant dans d'autres biotopes (bordures de prairies, haies, landes...) où elle exploite une grande diversité d'hôtes à la fois dans la faune sauvage (rongeurs, cervidés...) et domestique (bovins, ovins...), qui sont éventuellement des réservoirs d'agents pathogènes. En raison de l'hétérogénéité spatiale de ces différents milieux à l'échelle du paysage, on ne peut pas comprendre la propagation dans l'espace et dans le temps de ces maladies au sein des agro-écosystèmes sans prendre en compte la répartition de ces biotopes ainsi que la distribution et les mouvements des animaux. Le projet OSCAR (Outil de Simulation Cartographique à l'échelle du paysage Agricole du Risque acarologique ; ANR Agrobiosphère, 2012-2016) a pour objectif d'analyser la distribution observée du risque acarologique (défini comme le produit de la densité de tiques par la prévalence des agents pathogènes au sein des tiques), de mieux comprendre la dynamique spatio-temporelle des populations de tiques et d'établir des cartes prédictives du risque acarologique basées sur des scénarios de changement de structure du paysage. Il implique 5 laboratoires (2 du DSA, 1 d'EFPA et 2 du CNRS), qui ont participé aux travaux de collecte d'informations (présence d'animaux domestiques dans les parcelles, localisation de chevreuils équipés de colliers GPS, abondance des micromammifères estimée par piégeage, caractérisation des biotopes étudiés...) et de matériels biologiques (tiques, sangs...) dans 2 zones d'études (les zones Atelier Armorique et Vallons et Côteaux de Gascogne). Des travaux de biologie moléculaire ont permis de caractériser la variabilité génétique au sein des populations de tiques et de rechercher la présence de 3 agents pathogènes dans ces échantillons (Anaplasma phagocytophilum, Borrelia spp. et Babesia spp.). L'analyse des densités de tiques sur la végétation a montré de fortes variations à l'échelle du paysage (avec une absence de tiques en bordure de pâtures lorsque les haies sont trop réduites par exemple). Concernant l'abondance des micromammifères, nous avons observé qu'un réseau de haies et de bosquets plus dense est plus favorable aux mulots sylvestres, tandis que les campagnols roussâtres sont plus abondants dans les habitats boisés isolés. Les importantes fluctuations d'abondance interannuelles de ces rongeurs entraînent de fortes fluctuations des densités du stade nymphal des tiques sur la végétation une saison plus tard. Les prévalences (dans les tiques collectées sur la végétation) des 3 agents pathogènes étudiés se sont avérées faibles (2 à 5 %). Les prévalences d'A. phagocytophilum et de Babesia (B. venatorum et B. capreoli) dans les chevreuils se sont quant à elles révélées importantes (de 65 % à 85 %). L'analyse de la variabilité génétique d'A. phagocytophilum a montré l'existence de plusieurs clades génétiquement distants dont un plus particulièrement associé au chevreuil. Les analyses de génétique des populations des tiques à l'échelle du paysage ont révélé d'importants flux de gènes et une absence de structuration entre populations, suggérant une importante dispersion via les mouvements des hôtes. La dernière année du projet est consacrée à la réalisation d'un modèle spatialisé prenant de compte l'hétérogénéité du paysage afin de prédire les densités de tiques en fonction des différents éléments qui le composent et explorer ainsi par simulation comment la modification de la structure du paysage impactera les densités de tique