Biology subjects

Ryser-Degiorgis, M.-P.

Publications and source records attributed to Ryser-Degiorgis, M.-P..

5 recordsLinked to original sources

bioRxiv2025

What if wildlife health surveillance was not just for veterinarians? - Opportunistic use of population monitoring by camera traps for syndromic surveillance of the Eurasian lynx (Lynx lynx)

Fifty years after the reintroduction of the Eurasian lynx Lynx lynx to the Vosges and Swiss Jura mountains, the species remains in danger of extinction in France. The main threats it faces are habitat fragmentation, high anthropogenic mortality (mainly vehicle collision but also illegal killing) and low genetic diversity, but little is known about the importance of disease. Camera trapping surveillance provides crucial information for understanding population health status but includes many biases. To be more efficient, surveillance must combine several modalities. This work first presents the development of a protocol for clinical data collection by camera trapping, intended for biologists in charge of the populations monitoring. This method was then applied to the 3574 events, i.e. 270 identified individuals, present between 1997 and 2020 in the lynx photo identification database of the Wolf-Lynx Network (Reseau Loup-Lynx) of the French Biodiversity Agency (Office Francais de la Biodiversite). Seventeen percent of the lynx studied showed at least one change indicative of disease. The most common changes were skin disorders. The others were body condition, ocular or locomotor changes, lack of auriculas and rarely respiratory, behavioral, or digestive troubles. The latter changes were concentrated at the end of the study period, which also corresponded to the period with the most camera traps and therefore the most data. Finally, these observations complemented postmortem surveillance of the French lynx population carried out by the French network of epidemiological surveillance (Reseau SAGIR).

ecology↗

bioRxiv2025

Annotating opportunistic camera-trap images with conditions ofrecording, for the disease surveillance of Eurasian lynx (Lynxlynx)

The French population of the Eurasian lynx (Lynx lynx) is small and fragmented. Any emerging disease would endanger it even further, so health surveillance is crucial. Currently, health monitoring relies on lynx carcass surveillance. In parallel, the Eurasian lynx population is being monitored since 1997 through a large network of observers in different regions and this trove of camera-trap images could allow for the opportunistic detection of clinical signs. Camera traps have been used for a very long time in ecology and, more recently, in epidemiology to study e.g. sarcoptic mange. However, the quality of the images from camera traps varies, the details of the animals body are more or less clearly visible. This work examines how the quality of the images relates to the ability to detect cutaneous changes and abnormal body conditions. Different factors affect image quality and the detection of changes: intrinsic camera parameters like the type and settings of the camera trap, extrinsic factors like the external lighting conditions or the position of the animal in relation to the camera. In our data set, clearly visible cutaneous changes were associated with a different set of factors than visible abnormal body conditions. The camera-trap conditions currently used for ecological monitoring of the lynx are sufficiently diverse to allow for the general surveillance of abnormal health signs. However, for monitoring specific health signs, the camera settings as well as the shooting context should be optimized to ensure the best possible sensitivity and specificity of the detection.

ecology↗

bioRxiv2023

Analysis of a European general wildlife health surveillance program: chances, challenges and recommendations

In the context of a One Health perspective general wildlife health surveillance (GWHS) gains importance worldwide, as pathogen transmission among wildlife, domestic animals and humans raises health, conservation and economic concerns. However, GWHS programs operate in the face of legal, geographical, financial, or administrative conditions. The present study uses a multi-tiered approach to understand the current characteristics, strengths and gaps of a European GWHS that operates in a fragmented legislative and multi-stakeholder environment. The aim is to support the implementation or improvement of other GWHS systems by managers, surveillance experts, and administrations. To assess the current state of wildlife health investigations and trends within the GWHS, we analyzed 20 years of wildlife diagnostic data, conducted an online survey and phone interviews with official field partners (hunting administrators, game wardens and hunters), and performed a time-per-task analysis. Firstly, we found that infectious disease dynamics, the level of public awareness for specific diseases, research activities and increasing population sizes of in depth-monitored protected species, together with biogeographical and political boundaries all impacted case numbers and can present unexpected challenges to a GWHS. Secondly, we found that even a seemingly comprehensive GWHS can feature pronounced information gaps, with underrepresentation of common or easily recognizable diseases, blind spots in non-hunted species and only a fraction of discovered carcasses being submitted. Thirdly, we found that substantial amounts of wildlife health data may be available at local hunting administrations or disease specialist centers, but outside the reach of the GWHS and its processes. In conclusion, we recommend that fragmented and federalist GWHS programs like the one addressed require a central, consistent and accessible collection of wildlife health data. Also, considering the growing role of citizen observers in environmental research, we recommend using online reporting systems to harness decentrally available information and fill wildlife health information gaps.

zoology↗

bioRxiv2019

Identifying maintenance hosts and risk factors for infection with Dichelobacter nodosus in free-ranging wild ruminants in Switzerland: a prevalence study

Footrot is a worldwide economically important, painful, contagious bacterial hoof disease of domestic and wild ungulates caused by Dichelobacter nodosus (D. nodosus). Benign and virulent strains have been identified in sheep presenting mild and severe lesions, respectively. However, in Alpine ibex (Capra ibex) both strains have been associated with severe, fatal lesions. In Switzerland a nationwide footrot control program for sheep focusing on the virulent strain shall soon be implemented. The aim of this cross-sectional study was to estimate the nationwide prevalence of both strains of D. nodosus in four wild indigenous ruminant species and to identify potential susceptible maintenance hosts that could be a reinfection source for sheep. During two years (2017-2018), interdigital swabs of 1,821 wild indigenous ruminants species (Alpine ibex; Alpine chamois, Rupicapra rupicapra; roe deer, Capreolus capreolus; red deer, Cervus elaphus) were analysed by Real-Time PCR. Furthermore, observed interspecies interactions were documented for each sample. Overall, we report a low prevalence of D. nodosus in all four indigenous wild ruminants, for both the benign (1.97%, N = 36, of which 31 red deer) and virulent (0.05%, N = 1) strain of D. nodosus. Footrot lesions were documented in one ibex with the virulent strain, and in one ibex with the benign strain. Interactions with domestic livestock occurred mainly with cattle and sheep. In conclusion, the data suggest that domestic ungulates represent a significant source of infection for wild ungulates, while wild ruminants are likely irrelevant for the maintenance and spread of D. nodosus. Furthermore, we add evidence that both D. nodosus strains can be associated with severe disease in Alpine ibex. These data are crucial for the upcoming nationwide control program and reveal that wild ruminants should not be considered as a threat to footrot control in sheep in this context.

zoology↗

bioRxiv2019

Pelvic bone structures in free-ranging Eurasian lynx (Lynx lynx) from Switzerland: a radiological pelvimetry study

The observation of severe pelvic malformations in Eurasian lynx (Lynx lynx) from a population reintroduced to Switzerland raised the question as to whether inbreeding may contribute to the development of congenital pelvic malformations. We aimed at providing baseline data on the pelvic morphology of Eurasian lynx from the reintroduced populations in Switzerland, at assessing potential differences in pelvic conformation between the two main Swiss populations, among age classes and between sexes, and at detecting pelvic anomalies. We performed measurements of 10 pelvic parameters on the radiographs of 57 lynx of both sexes and different ages taken from 1997-2015. We calculated two ratios (vertical diameter/acetabula; sagittal diameter/transversal diameter) and two areas (pelvic outlet and inlet) to describe the shape of the pelvis. Our results showed that the Eurasian lynx is a mesatipelvic species, with a pelvis length corresponding to approximatively 20% of the body length. We found no statistically significant differences between the two examined populations but observed growth-related pelvis size differences among age groups. Sexual dimorphism was obvious in the adult age group only: two parameters reflecting pelvic width were larger in females, likely to meet the physiological requirements of parturition. By contrast, pelvis length, conjugata vera, diagonal conjugata, vertical diameter and sagittal diameter were larger in males, in agreement with their larger body size. Accordingly, the ratio between the sagittal and transversal diameters was significantly larger in males, i.e. adult males have a different pelvic shape than adult females. Furthermore, pelvimetry highlighted one adult individual with values outside the calculated reference range, suggesting a possible congenital or developmental pathological morphology of the internal pelvis. Our work generated baseline data of the pelvic morphology including growth and sexual dimorphism of the Eurasian lynx. These data could also be useful for estimating age and sex in skeletal remains.

zoology↗