Detection of Pathogens and Ticks on Sedentary and Migratory Birds in Two Corsican Wetlands (France, Mediterranean Area).

Birds are one of the most species-diverse vertebrate groups and are susceptible to numerous hematophagous ectoparasites. Migratory birds likely contribute to the circulation of these ectoparasites and their associated pathogens. One of the many migration paths crosses the Mediterranean islands including Corsica and its wetlands, which are migration stopovers. In our study, we collected blood samples and hematophagous ectoparasites in migratory and sedentary bird populations in two coastal lagoons: Biguglia and Gradugine. A total of 1377 birds were captured from which 762 blood samples, 37 louse flies, and 44 ticks were collected. All the louse flies were identified as Ornithomya biloba and all the ticks were from the Ixodes genus: Ixodes sp. (8.5%), I. accuminatus/ventalloi (2.9%), I. arboricola/lividus (14.3%), I. frontalis (5.7%) and I. ricinus (68.6%). Five pathogens were detected: Anaplasma phagocytophilum, Erhlichia chaffeensis, and Rickettsia helvetica in ticks, and Trypanosoma sp. in louse flies. Ehrlichia chaffeensis and the West Nile virus were both detected in bird blood samples in Corsica. This is the first report of these tick, louse fly and pathogen species isolated on the bird population in Corsica. Our finding highlights the importance of bird populations in the presence of arthropod-borne pathogens in Corsican wetlands.

Diversity of Tick-Borne Pathogens in Tick Larvae Feeding on Breeding Birds in France.

Birds play a role in maintaining tick-borne diseases by contributing to the multiplication of ticks and pathogens on a local scale during the breeding season. In the present study, we describe the diversity of tick and pathogen species of medical and veterinary importance in Europe hosted by 1040 captured birds (56 species) during their breeding season in France. Of the 3114 ticks collected, Ixodes ricinus was the most prevalent species (89.5%), followed by I. frontalis (0.8%), I. arboricola (0.7%), Haemaphysalis concinna (0.5%), H. punctata (0.5%), Hyalomma spp. (0.2%), and Rhipicephalus spp. (0.06%). Because they may be representative of the bird infection status for some pathogen species, 1106 engorged tick larvae were screened for pathogens. Borrelia burgdorferi sensu lato was the most prevalent pathogen genus in bird-feeding larvae (11.7%), followed by Rickettsia spp. (7.4%), Anaplasma spp. (5.7%), Babesia spp. (2.3%), Ehrlichia spp. (1.4%), and B. miyamotoi (1%). Turdidae birds (Turdus merula and T. philomelos), Troglodytes troglodytes, and Anthus trivialis had a significantly higher prevalence of B. burgdorferi s.l.-infected larvae than other pathogen genera. This suggests that these bird species could act as reservoir hosts for B. burgdorferi s.l. during their breeding season, and thus play an important role in acarological risk.

Research effort on birds' reservoir host potential for Lyme borreliosis: A systematic review and perspectives.

Zoonotic tick-borne diseases threat human and animal health. Understanding the role of hosts in the production of infected ticks in an epidemiological system is essential to be able to design effective measures to reduce the exposure of humans and animals to infectious tick bites. The reservoir host potential, that is, number of infected ticks produced by a host species, depends on three components: tick production, realized reservoir competence and host density. The parameters and factors that determine the reservoir host potential need to be characterized to achieve a robust understanding of the dynamics of pathogen-tick-host systems, and thus to mitigate the acarological risk of emerging infections. Few studies have investigated the role of birds in the local spread of Lyme borreliosis Borrelia. Knowledge of the research effort on the reservoir host potential of birds in Lyme borreliosis Borrelia circulation is necessary to prioritize future research on this topic. We provide a systematic review of the research effort on components of the reservoir host potential of wild birds for Lyme borreliosis Borrelia circulation, and factors that modulate these components in the European epidemiological system. Our review of 242 selected publications showed that tick production has been 1.4 and 21 times more studied than realized reservoir competence and bird density respectively. Only one study achieved to characterize the global host reservoir potential of birds in a given epidemiological system. Investigated factors were mostly related to bird species identity, individual characteristics of birds and tick characteristics, whereas the influence of bird life-history traits have been largely under-investigated. Because simultaneous characterization of all parameters is notoriously complex, interdisciplinary research is needed to combine and accumulate independent field and laboratory investigations targeting each parameter on specific epidemiological system or host species. This can help gain an integrated appraisal of the functioning of the studied system at a local scale.

Evaluating Functional Dispersal in a Nest Ectoparasite and Its Eco-Epidemiological Implications.

Functional dispersal (between-site movement, with or without subsequent reproduction) is a key trait acting on the ecological and evolutionary trajectories of a species, with potential cascading effects on other members of the local community. It is often difficult to quantify, and particularly so for small organisms such as parasites. Understanding this life history trait can help us identify the drivers of population dynamics and, in the case of vectors, the circulation of associated infectious agents. In the present study, functional dispersal of the soft tick Ornithodoros maritimus was studied at a small scale, within a colony of yellow-legged gulls (Larus michahellis). Previous work showed a random distribution of infectious agents in this tick at the within-colony scale, suggesting frequent tick movement among nests. This observation contrasts with the presumed strong endophilic nature described for this tick group. By combining an experimental field study, where both nest success and tick origin were manipulated, with Capture-Mark-Recapture modeling, dispersal rates between nests were estimated taking into account tick capture probability and survival, and considering an effect of tick sex. As expected, tick survival probability was higher in successful nests, where hosts were readily available for the blood meal, than in unsuccessful nests, but capture probability was lower. Dispersal was low overall, regardless of nest state or tick sex, and there was no evidence for tick homing behavior; ticks from foreign nests did not disperse more than ticks in their nest of origin. These results confirm the strong endophilic nature of this tick species, highlighting the importance of life cycle plasticity for adjusting to changes in host availability. However, results also raise questions with respect to the previously described within-colony distribution of infectious agents in ticks, suggesting that tick dispersal either occurs over longer temporal scales and/or that transient host movements outside the breeding period result in vector exposure to a diverse range of infectious agents.