Exposure of yellow-legged gulls to Toxoplasma gondii along the Western Mediterranean coasts: Tales from a sentinel

Abstract

Efficiently tracking and anticipating the dynamics of infectious agents in wild populations requires the gathering of large numbers of samples, if possible at several locations and points in time, which can be a challenge for some species. Testing for the presence of specific maternal antibodies in egg yolks sampled on the colonies could represent an efficient way to quantify the exposure of breeding females to infectious agents, particularly when using an abundant and widespread species, such as the yellow-legged gull ( Larus michahellis ). We used such an approach to explore spatio-temporal patterns of exposure to Toxoplasma gondii , a pathogenic protozoan responsible of toxoplasmosis in humans and other warm-blooded vertebrates. First, we tested the validity of this approach by exploring the repeatability of the detection of specific antibodies at the egg level using two different immunoassays and at the clutch level using an occupancy model. Then, samples gathered in 15 colonies from France, Spain and Tunisia were analysed using an immunoassay detecting antibodies specifically directed against T. gondii . Prevalence of specific antibodies in eggs was overall high while varying significantly among colonies. These results revealed that T. gondii circulated at a large spatial scale in the western Mediterranean yellow-legged gull population, highlighting its potential role in the maintenance community of this parasite. Additionally, this study illustrates how species commensal to human populations like large gulls can be used as wildlife sentinels for the tracking of infectious agents at the human-wildlife interface, notably by sampling eggs.

Serological and Molecular Investigation on Toxoplasma gondii Infection in Wild Birds

“…The results from this preliminary report would fit with data referred by other countries, and four raptors out of 15 (27%) were seropositive. Four out of 18 seagulls (22.3%) scored seropositive, in full agreement with Cabezon et al [16] who first reported the occurrence of antibodies (21%) versus T. gondii in 525 seagull chicks, and with Gamble et al [17], who reported a large exposure of yellow-legged gull to the parasite by checking 1122 eggs and hypothesized of their involvement in the maintenance and circulation of toxoplasma, suggesting that large gulls could be used as epidemiological sentinels at the human–wildlife interface.…”

Protein Deimination and Extracellular Vesicle Profiles in Antarctic Seabirds

“…Numerous studies have examined levels of a range of heavy metal and other contaminants [39,[45][46][47]. Similarly, a range of seabird species have been screened for specific pathogens [48], including for the agent of avian cholera (Pasteurella multocida) [49][50][51][52], avian pox [53] as well as other bacterial [54], viral [55,56] and parasitic infections [57][58][59][60][61]. However, less research has been carried out on immunological markers, which should be indicative of general health in seabirds [62][63][64][65][66].…”

Pathogen transmission risk by opportunistic gulls moving across human landscapes

“…Moreover, the utilization of wetlands or estuaries by infected-gulls enhances the probability for pathogen transmission to other wildlife species 31 . Garbage dumps are also assumed to facilitate the infection of gulls by pathogens present in the human organic garbage, as well as cross-species and cross-individual transmission 13,18 . Yet, this habitat was seldom used by gulls in our study, due to its low availability in the area used by tracked-gulls (there are only two dumps in the area surrounding the breeding colony 27 ).…”

“…This facilitates pathogen spill-over between wildlife and humans, both ways, and there are concerns that this may facilitate the evolution of new zoonotic pathogens 6,8–10 . Notably, urban gulls threaten public health because they shed bacterial pathogens, antibiotic-resistant bacteria, and viruses 5,11–13 . This has become a public health problem, yet little is known about how gulls spread zoonoses in space and time 5,13,14 .…”

“…Notably, urban gulls threaten public health because they shed bacterial pathogens, antibiotic-resistant bacteria, and viruses 5,11–13 . This has become a public health problem, yet little is known about how gulls spread zoonoses in space and time 5,13,14 . The lack of information on the dissemination process of zoonotic pathogens weakens risk assessments and management plans 15 .…”