Samantha Sambado

All Publications

• Wildfire disturbance and ecological cascades: Teasing apart the direct and indirect effects of fire on tick populations JOURNAL OF APPLIED ECOLOGY Sambado, S., Dayton, G., Zilliacus, K. M., Dewees, S., MacDonald, A. J., Briggs, C. J. 2025

  View details for DOI 10.1111/1365-2664.70194

  View details for Web of Science ID 001599192000001

• The paradoxical impact of drought on West Nile virus risk: insights from long-term ecological data. Proceedings. Biological sciences Sambado, S., Sipin, T. J., Rennie, Z., Larsen, A., Cunningham, J., Quandt, A., Sousa, D., MacDonald, A. J. 2025; 292 (2054): 20251365

  Abstract

  Mosquito-borne diseases are deeply embedded within ecological communities, with environmental changes-particularly climate change-shaping their dynamics. Increasingly intense droughts across the globe have profound implications for the transmission of these diseases, as drought conditions can alter mosquito breeding habitats, host-seeking behaviours and mosquito-host contact rates. To quantify the effect of drought on disease transmission, we use West Nile virus as a model system and leverage a robust mosquito and virus dataset consisting of over 500 000 trap nights collected from 2010 to 2023, spanning a historic drought period followed by atmospheric rivers. We pair this surveillance dataset with a novel modelling approach that incorporates monthly changes in bird host community competence, along with drought conditions, to estimate the effect of drought severity on West Nile virus risk using panel regression models. Our results show that while drought decreases mosquito abundances, it paradoxically increases West Nile virus infection rates. This counterintuitive pattern probably stems from reduced water availability, which concentrates mosquitoes and pathogen-amplifying bird hosts around limited water sources, thereby increasing disease transmission risk. However, the magnitude of the effect depends critically on mosquito species, suggesting species-specific behavioural traits are key to understanding the effect of drought on mosquito-borne disease risk across real landscapes.

  View details for DOI 10.1098/rspb.2025.1365

  View details for PubMedID 40897323

  View details for PubMedCentralID PMC12404801

• Climate differentially impacts ticks infected and uninfected with <i>Borrelia burgdorferi</i> SCIENCE ADVANCES Broughton, H., Crews, A., Lilly, M., Sambado, S., Salomon, J., Lawrence, A., Ring, K., Clark, J., Shaw, G., Summers, S., Nakano, A., Swei, A. 2025; 11 (29): eads2181

  Abstract

  Climate change continues to alter the behavior and distribution of species worldwide, with major ramifications for the transmission and risk of infectious diseases, including those caused by zoonotic vector-borne pathogens. This study explores the potential implications of climate change for one such pathogen, Borrelia burgdorferi (the causative agent of human Lyme disease), in Ixodes pacificus ticks of the far-western United States. Nymphal tick infection prevalence and density are compared against several metrics for climate, while also accounting for habitat fragmentation, mammalian species richness, and rodent tick burden to eliminate confounding variables. Findings show that climate extremes, such as those forecast with climate change, correlate with a reduction in B. burgdorferi prevalence in nymphal ticks despite nominal impacts on uninfected tick density, contrasting traditional hypotheses that these changes will increase vector-borne pathogens.

  View details for DOI 10.1126/sciadv.ads2181

  View details for Web of Science ID 001531794500030

  View details for PubMedID 40680127

  View details for PubMedCentralID PMC12273747

• Functional vertebrate group diversity differentially impacts vector-borne pathogen transmission and genetic diversity ECOSPHERE Lilly, M., Crews, A., Lawrence, A., Salomon, J., Sambado, S., Cerna, L., Ring, K., Peng, C., Shaw, G., Summers, S., Swei, A. 2025; 16 (6)

  View details for DOI 10.1002/ecs2.70292

  View details for Web of Science ID 001510320600001

• Variable effects of wildlife and livestock on questing tick abundance across a topographical-climatic gradient ECOSPHERE Copeland, S., Sambado, S., Orr, D., Bui, A., Swei, A., Young, H. S. 2025; 16 (2)

  View details for DOI 10.1002/ecs2.70190

  View details for Web of Science ID 001431122500001

• The roles of habitat isolation, landscape connectivity and host community in tick-borne pathogen ecology ROYAL SOCIETY OPEN SCIENCE Shaw, G., Lilly, M., Mai, V., Clark, J., Summers, S., Slater, K., Karpathy, S., Nakano, A., Crews, A., Lawrence, A., Salomon, J., Sambado, S., Swei, A. 2024; 11 (11): 240837

  Abstract

  Habitat loss and forest fragmentation are often linked to increased pathogen transmission, but the extent to which habitat isolation and landscape connectivity affect disease dynamics through movement of disease vectors and reservoir hosts has not been well examined. Tick-borne diseases are the most prevalent vector-borne diseases in the United States and on the West Coast, Ixodes pacificus is one of the most epidemiologically important vectors. We investigated the impacts of habitat fragmentation on pathogens transmitted by I. pacificus and sought to disentangle the effects of wildlife communities and landscape metrics predictive of pathogen diversity, prevalence and distribution. We collected pathogen data for four co-occurring bacteria transmitted by I. pacificus and measured wildlife parameters. We also used spatial data and cost-distance analysis integrating expert opinions to assess landscape metrics of habitat fragmentation. We found that landscape metrics were significant predictors of tick density and pathogen prevalence. However, wildlife variables were essential when predicting the prevalence and distribution of pathogens reliant on wildlife reservoir hosts for maintenance. We found that landscape structure was an informative predictor of tick-borne pathogen richness in an urban matrix. Our work highlights the implications of large-scale land management on human disease risk.

  View details for DOI 10.1098/rsos.240837

  View details for Web of Science ID 001348895400001

  View details for PubMedID 39507992

  View details for PubMedCentralID PMC11540178

• Remote sensing of temperature-dependent mosquito and viral traits predicts field surveillance-based disease risk ECOLOGY MacDonald, A. J., Hyon, D., Sambado, S., Ring, K., Boser, A. 2024; 105 (11): e4420

  Abstract

  Mosquito-borne diseases contribute substantially to the global burden of disease, and are strongly influenced by environmental conditions. Ongoing and rapid environmental change necessitates improved understanding of the response of mosquito-borne diseases to environmental factors like temperature, and novel approaches to mapping and monitoring risk. Recent development of trait-based mechanistic models has improved understanding of the temperature dependence of transmission, but model predictions remain challenging to validate in the field. Using West Nile virus (WNV) as a case study, we illustrate the use of a novel remote sensing-based approach to mapping temperature-dependent mosquito and viral traits at high spatial resolution and across the diurnal cycle. We validate the approach using mosquito and WNV surveillance data controlling for other key factors in the ecology of WNV, finding strong agreement between temperature-dependent traits and field-based metrics of risk. Moreover, we find that WNV infection rate in mosquitos exhibits a unimodal relationship with temperature, peaking at ~24.6-25.2°C, in the middle of the 95% credible interval of optimal temperature for transmission of WNV predicted by trait-based mechanistic models. This study represents one of the highest resolution validations of trait-based model predictions, and illustrates the utility of a novel remote sensing approach to predicting mosquito-borne disease risk.

  View details for DOI 10.1002/ecy.4420

  View details for Web of Science ID 001319928500001

  View details for PubMedID 39319755

  View details for PubMedCentralID PMC11534503