@article{farthing_dawson_sanderson_seger_lanzas_2021, title={Combining epidemiological and ecological methods to quantify social effects on Escherichia coli transmission}, volume={8}, ISSN={["2054-5703"]}, url={https://doi.org/10.1098/rsos.210328}, DOI={10.1098/rsos.210328}, abstractNote={
            Enteric microparasites like
            Escherichia coli
            use multiple transmission pathways to propagate within and between host populations. Characterizing the relative transmission risk attributable to host social relationships and direct physical contact between individuals is paramount for understanding how microparasites like
            E. coli
            spread within affected communities and estimating colonization rates. To measure these effects, we carried out commensal
            E. coli
            transmission experiments in two cattle (
            Bos taurus
            ) herds, wherein all individuals were equipped with real-time location tracking devices. Following transmission experiments in this model system, we derived temporally dynamic social and contact networks from location data. Estimated social affiliations and dyadic contact frequencies during transmission experiments informed pairwise accelerated failure time models that we used to quantify effects of these sociobehavioural variables on weekly
            E. coli
            colonization risk in these populations. We found that sociobehavioural variables alone were ultimately poor predictors of
            E. coli
            colonization in feedlot cattle, but can have significant effects on colonization hazard rates (
            p
            ≤ 0.05). We show, however, that observed effects were not consistent between similar populations. This work demonstrates that transmission experiments can be combined with real-time location data collection and processing procedures to create an effective framework for quantifying sociobehavioural effects on microparasite transmission.
          }, number={10}, journal={ROYAL SOCIETY OPEN SCIENCE}, author={Farthing, Trevor S. and Dawson, Daniel E. and Sanderson, Mike W. and Seger, Hannah and Lanzas, Cristina}, year={2021}, month={Oct} }
 @article{dawson_rasmussen_peng_lanzas_2021, title={Inferring environmental transmission using phylodynamics: a case-study using simulated evolution of an enteric pathogen}, volume={18}, ISSN={["1742-5662"]}, url={https://doi.org/10.1098/rsif.2021.0041}, DOI={10.1098/rsif.2021.0041}, abstractNote={Indirect (environmental) and direct (host–host) transmission pathways cannot easily be distinguished when they co-occur in epidemics, particularly when they occur on similar time scales. Phylodynamic reconstruction is a potential approach to this problem that combines epidemiological information (temporal, spatial information) with pathogen whole-genome sequencing data to infer transmission trees of epidemics. However, factors such as differences in mutation and transmission rates between host and non-host environments may obscure phylogenetic inference from these methods. In this study, we used a network-based transmission model that explicitly models pathogen evolution to simulate epidemics with both direct and indirect transmission. Epidemics were simulated according to factorial combinations of direct/indirect transmission proportions, host mutation rates and conditions of environmental pathogen growth. Transmission trees were then reconstructed using the phylodynamic approach SCOTTI (structured coalescent transmission tree inference) and evaluated. We found that although insufficient diversity sets a lower bound on when accurate phylodynamic inferences can be made, transmission routes and assumed pathogen lifestyle affected pathogen population structure and subsequently influenced both reconstruction success and the likelihood of direct versus indirect pathways being reconstructed. We conclude that prior knowledge of the likely ecology and population structure of pathogens in host and non-host environments is critical to fully using phylodynamic techniques.}, number={179}, journal={JOURNAL OF THE ROYAL SOCIETY INTERFACE}, author={Dawson, Daniel and Rasmussen, David and Peng, Xinxia and Lanzas, Cristina}, year={2021}, month={Jun} }
 @article{lashnits_dawson_breitschwerdt_lanzas_2019, title={Ecological and Socioeconomic Factors Associated with Bartonella henselae Exposure in Dogs Tested for Vector-Borne Diseases in North Carolina}, volume={19}, ISSN={1530-3667 1557-7759}, url={http://dx.doi.org/10.1089/vbz.2018.2397}, DOI={10.1089/vbz.2018.2397}, abstractNote={Bartonella henselae is a zoonotic vector-borne pathogen affecting both humans and dogs. Little is known about the epidemiology of B. henselae in dogs, including risk factors associated with exposure. The objectives of this study were to map the current distribution of B. henselae in dogs in North Carolina (NC) and to identify ecological and socioeconomic factors influencing B. henselae seroreactivity. Results from 4446 B. henselae serology samples from dogs in NC submitted by veterinarians for clinical diagnostic testing to the North Carolina State University College of Veterinary Medicine Vector Borne Disease Diagnostic Laboratory between January 1, 2004 and December 31, 2015 were retrospectively reviewed. These results were used to generate a map of B. henselae seroreactivity. To account for sparsely sampled areas, statistical smoothing using head banging and areal interpolation kriging was performed. Using previously described risk factors for exposure to canine tick-borne diseases, eight multivariable logistic regression models based on biologically plausible hypotheses were tested, and a final model was selected using an Akaike's Information Criterion weighted-average approach. Seroreactivity among dogs tested for vector-borne disease was variable across the state: higher along the southern/eastern coastal plains and eastern Piedmont, and lower in the western mountains. Of 25 explanatory factors considered, the model combining demographic, socioeconomic, climatic, and land use variables fits best. Based on this model, female intact sex and increasing percentage of the county with low-intensity development and evergreen forest were associated with higher seroreactivity. Conversely, moderate development, increasing median household income, and higher temperature range and relative humidity were associated with lower seroreactivity. This model could be improved, however, by including local and host-scale factors that may play a significant role in dogs' exposure.}, number={8}, journal={Vector-Borne and Zoonotic Diseases}, publisher={Mary Ann Liebert Inc}, author={Lashnits, Erin W. and Dawson, Daniel E. and Breitschwerdt, Edward and Lanzas, Cristina}, year={2019}, month={Aug}, pages={582–595} }
 @article{pandey_dawson_2019, title={The shapes of virulence to come}, ISSN={["2050-6201"]}, DOI={10.1093/emph/eoy037}, abstractNote={A pathogen’s virulence is the negative impact it has on a host. As a trait, virulence correlates with pathogen fitness, and hence can undergo selection. In directly transmitted pathogens, higher within-host growth rates are associated with higher transmission rates and greater fitness of the pathogen. Higher growth rates often result in higher virulence, resulting in the co-selection of virulence along with fitness. When expressed as mortality, increased virulence limits the amount of time an infected individual can transmit pathogens. This sets up a trade-off between infection duration and transmission probability, theoretically resulting in an optimal level of intermediate virulence [1] (Fig. 1). However, the nature of such trade-offs depends upon the life history strategies of both the pathogen and the host. Therefore, understanding virulence evolution pressures in different disease systems (e.g. vector-borne, environmentally transmitted and opportunistic) is critical to forecasting disease dynamics under changing conditions. EXAMPLE IN HUMAN BIOLOGY AND PUBLIC HEALTH}, number={1}, journal={EVOLUTION MEDICINE AND PUBLIC HEALTH}, author={Pandey, Aakash and Dawson, Daniel E.}, year={2019}, pages={3–3} }
 @article{dawson_farthing_sanderson_lanzas_2019, title={Transmission on empirical dynamic contact networks is influenced by data processing decisions}, volume={26}, ISSN={["1755-4365"]}, url={https://doi.org/10.1016/j.epidem.2018.08.003}, DOI={10.1016/j.epidem.2018.08.003}, abstractNote={Dynamic contact data can be used to inform disease transmission models, providing insight into the dynamics of infectious diseases. Such data often requires extensive processing for use in models or analysis. Therefore, processing decisions can potentially influence the topology of the contact network and the simulated disease transmission dynamics on the network. In this study, we examine how four processing decisions, including temporal sampling window (TSW), spatial threshold of contact (SpTh), minimum contact duration (MCD), and temporal aggregation (daily or hourly) influence the information content of contact data (indicated by changes in entropy) as well as disease transmission model dynamics. We found that changes made to information content by processing decisions translated to significant impacts to the transmission dynamics of disease models using the contact data. In particular, we found that SpTh had the largest independent influence on information content, and that some output metrics (R0, time to peak infection) were more sensitive to changes in information than others (epidemic extent). These findings suggest that insights gained from transmission modeling using dynamic contact data can be influenced by processing decisions alone, emphasizing the need to carefully consideration them prior to using contact-based models to conduct analyses, compare different datasets, or inform policy decisions.}, journal={EPIDEMICS}, publisher={Elsevier BV}, author={Dawson, Daniel E. and Farthing, Trevor S. and Sanderson, Michael W. and Lanzas, Cristina}, year={2019}, month={Mar}, pages={32–42} }
 @article{dawson_keung_napoles_vella_chen_sanderson_lanzas_2018, title={Investigating behavioral drivers of seasonal Shiga-Toxigenic Escherichia Coli (STEC) patterns in grazing cattle using an agent-based model}, volume={13}, ISSN={["1932-6203"]}, url={http://europepmc.org/articles/PMC6179278}, DOI={10.1371/journal.pone.0205418}, abstractNote={The causes of seasonal variability in pathogen transmission are not well understood, and have not been comprehensively investigated. In an example for enteric pathogens, incidence of Escherichia coli O157 (STEC) colonization in cattle is consistently higher during warmer months compared to cooler months in various cattle production systems. However, actual mechanisms for this seasonality remain elusive. In addition, the influence of host (cattle) behavior on this pattern has not been thoroughly considered. To that end, we constructed a spatially explicit agent-based model that accounted for the effect of temperature fluctuations on cattle behavior (direct contact among cattle and indirect between cattle and environment), as well as its effect on pathogen survival in the environment. We then simulated the model in a factorial approach to evaluate the hypothesis that temperature fluctuations can lead to seasonal STEC transmission dynamics by influencing cattle aggregation, grazing, and drinking behaviors. Simulation results showed that higher temperatures increased the frequency at which cattle aggregated under shade in pasture, resulting in increased direct contact and transmission of STEC between individual cattle, and hence higher incidence over model simulations in the warm season. In contrast, increased drinking behavior during warm season was not an important transmission pathway. Although sensitivity analyses suggested that the relative importance of direct vs. indirect (environmental) pathways depend to upon model parameterization, model simulations indicated that factors influencing cattle aggregation, such as temperature, were likely strong drivers of transmission dynamics of enteric pathogens.}, number={10}, journal={PLOS ONE}, author={Dawson, Daniel E. and Keung, Jocelyn H. and Napoles, Monica G. and Vella, Michael R. and Chen, Shi and Sanderson, Michael W. and Lanzas, Cristina}, year={2018}, month={Oct} }
 @article{reategui-zirena_fidder_olson_dawson_bilbo_salice_2017, title={Transgenerational endpoints provide increased sensitivity and insight into multigenerational responses of Lymnaea stagnalis exposed to cadmium}, volume={224}, ISSN={["1873-6424"]}, DOI={10.1016/j.envpol.2017.02.040}, abstractNote={Ecotoxicology provides data to inform environmental management. Many testing protocols do not consider offspring fitness and toxicant sensitivity. Cadmium (Cd) is a well-studied and ubiquitous toxicant but little is known about the effects on offspring of exposed parents (transgenerational effects). This study had three objectives: to identify endpoints related to offspring performance; to determine whether parental effects would manifest as a change in Cd tolerance in offspring and how parental exposure duration influenced the manifestation of parental effects. Adult snails were exposed to Cd 0, 25, 50, 100, 200 and 400 μg Cd/L for eight weeks. There were effects on adult endpoints (e.g., growth, reproduction) but only at the highest concentrations (>100 μg/L). Alternatively, we observed significant transgenerational effects at all Cd concentrations. Surprisingly, we found increased Cd tolerance in hatchlings from all parental Cd exposure concentrations even though eggs and hatchlings were in Cd-free conditions for 6 weeks. Explicit consideration of offspring performance adds value to current toxicity testing protocols. Parental exposure duration has important implications for offspring effects and that contaminant concentrations that are not directly toxic to parents can cause transgenerational changes in resistance that have significant implications for toxicity testing and adaptive responses.}, journal={ENVIRONMENTAL POLLUTION}, author={Reategui-Zirena, Evelyn G. and Fidder, Bridgette N. and Olson, Adric D. and Dawson, Daniel E. and Bilbo, Thomas R. and Salice, Christopher J.}, year={2017}, month={May}, pages={572–580} }