Biology subjects

Dürr, S.

Publications and source records attributed to Dürr, S..

3 recordsLinked to original sources

bioRxiv2026

Contact heterogeneity in network reconstruction: evaluating synthetic graph generators for rabies transmission modeling

Canine rabies remains endemic across much of Africa and Asia, causing approximately 59,000 global deaths yearly. Network-based models that reconstruct contact patterns are central to predicting canine rabies transmission and to designing targeted interventions, but the choice of network generator algorithm may alter network structure and outbreak predictions. We therefore compared five network generators using five empirical free-roaming dog contact networks from Chad, Indonesia, and Guatemala in network topology and outbreak dynamics under susceptible-exposed-infectious-removed (SEIR) and susceptible-infectious-susceptible (SIS) transmission across a range of infectious-period lengths. We found that the degree-corrected stochastic block model (DCSBM) most consistently reproduces both empirical topology and outbreak dynamics, achieving a Mahalanobis distance of 17.6 to the empirical Chad network compared to a range of 21.0 to 220.7 across the other generators and yielding similar results for the other four locations. Moreover, the SIS and SEIR outbreak dynamics reveal that the DCSBM overall best reproduces the simulated empirical outbreak dynamics, but that the consequences of generator choice are not uniform: network reconstruction matters most precisely for short-infectious-window pathogens like canine rabies and progressively less for long-infectious-window pathogens. By an infectious window of nine days, the outbreak dynamics across four of five generators converge to within two percentage points of the empirical reference, even when their underlying topologies differ substantially. This pathogen-dependent sensitivity offers a principled criterion for when generator selection is consequential and when it is not. This work reiterates the importance of both degree heterogeneity and community structure for faithful contact-network reconstruction in canine rabies modeling, particularly for short-window infectious diseases where contact heterogeneity drives transmission. For longer-window pathogens, simpler generators are likely adequate.

ecology↗

bioRxiv2019

Using Unmanned Aerial Vehicles (UAV) for free-roaming dog population size estimation

Population size estimation is performed for several reasons including disease surveillance and control, for example to design adequate control strategies such as vaccination programs or to estimate a vaccination campaign coverage. In this study, we aimed at assessing the benefits and challenges of using Unmanned Aerial Vehicles (UAV) to estimate the size of free-roaming domestic dog (FRDD) populations and compare the results with two regularly used methods for population estimations: a Bayesian statistical model based on capture-recapture data and the human:dog ratio estimation. Three studies sites of one square kilometer were selected in Peten department, Guatemala. UAV flight were conducted twice during two consecutive days per study site. The UAVs camera was set to regularly take pictures and cover the entire surface of the selected areas. A door-to-door survey was conducted in the same areas, all available dogs were marked with a collar and owner were interviewed. Simultaneously to the UAVs flight, transect walks were performed and the number of collared and non-collared dogs were recorded. Data collected during the interviews and the number of dogs counted during the transect walks informed a Bayesian statistical model. The number of dogs counted on the UAVs pictures and the estimates given by the Bayesian statistical model, as well as the estimates derived from using a 5:1 human:dog ratio were compared to dog census data. FRDD could be detected using the UAVs method. However, the method lacked of sensitivity, which could be overcome by choosing the flight timing and the study area wisely, or using infrared camera or automatic detection of the dogs. We also suggest to combine UAV and capture-recapture methods to obtain reliable FRDD population size estimated. This publication may provide helpful directions to design dog population size estimation methods using UAV.

ecology↗

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↗