Biology subjects

Bournez, L.

Publications and source records attributed to Bournez, L..

3 recordsLinked to original sources

bioRxiv2023

Tick-borne zoonotic flaviviruses and Borrelia infections in wildlife hosts: what have field studies contributed?

Tick-borne flaviviruses and Borrelia spp. are globally spread pathogens of zoonotic potential that are maintained by a transmission cycle at the interface between ticks and vertebrate hosts, mainly wild animals. Aside data on pathogen burden in ticks, information on the status of various hosts relative to infection could be critical. We reviewed how those infections have been studied in wildlife species in the field to discuss how collected data provided relevant epidemiological information and identify needs for further studies. The literature was screened for populational studies on direct or antibody detection for tick-borne Borrelia spp. and flaviviruses in animals, in the wild. Overall, Borrelia spp. were more studied (73% of case studies, representing 297 host species) than flaviviruses (27% of case studies, representing 114 host species). Studies on both Borrelia spp. and flaviviruses focused mainly on the same species, namely bank vole and yellow-necked mouse. Most studies were order-specific and cross-sectional, reporting prevalence at various locations, but with little insight into the underlying epidemiological dynamics. Species with potential to act as reservoir hosts were overlooked, notably passerine birds. We highlight the necessity of collecting both demographics and infection data in wildlife studies, and to consider communities of species, to better estimate zoonotic risk potential in the One Health context.

ecology↗

bioRxiv2023

The distribution, phenology, host range and pathogen prevalence of Ixodes ricinus in France: a systematic map and narrative review

The tick Ixodes ricinus is the most important vector species of infectious diseases in European France. Understanding its distribution, phenology, and host species use, along with the distribution and prevalence of associated pathogens at national scales is essential for developing prevention strategies. The aim of this paper is to provide a systematic map and narrative review of the existing knowledge on the eco-epidemiology of I. ricinus in France. Using literature published up to 2020, the present paper provides a distribution map for the species and a summary of environmental factors explaining observed geographical differences in phenology and temporal differences in abundance. The diversity of vertebrate host species used by this tick, along with their degree of infestation when available, are presented and discussed with respect to their potential contribution to the population dynamics of I. ricinus and the circulation of tick-borne zoonotic pathogens. Prevalence data of detected pathogens are summarised in different maps. Results from 187 identified references show that the species is present in most departments, but scarce under Mediterranean climate and in coastal habitats. Its phenology is generally bimodal with variations depending on climate. Abundance seems positively influenced by forest cover and host abundance. Rodents and ruminants are the most studied species groups, but the diversity of sampling protocols (e.g., location, season, exhaustivity of inspection) precluded direct comparisons between species groups. Data on pathogens are patchy, with most studies conducted near research units. Among pathogens, Borrelia burgdorferi sensu lato is the most searched for in ticks and seems more prevalent in north-eastern and central France. The review carried out here has made it possible to highlight the gaps in our knowledge of tick-host-pathogen interactions, their ecology and their distribution, and the need to address these gaps in order to optimize tick and tick-borne diseases prevention and control strategies.

ecology↗

bioRxiv2022

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.

ecology↗