Our laboratory uses quantitative methods to understand the epidemiology and ecology of mosquito borne viruses. We rely on modeling as a framework to improve our understanding of transmission mechanisms and to guide field and laboratory research that explicitly acknowledges the complexities of both the natural processes and the surveillance “lens” through which they are observed to produce answers that are evidence-based and readily interpretable by policymakers.
Our research is highly collaborative, and relies on a diverse range of extramural resources, from federal agencies to state and local public health and mosquito control agencies. Much of our research has focused on the West Nile virus (WNV) system, and our interests include other vector-borne pathogens of global importance, especially dengue virus (DENV) and other emerging arboviruses in Peru.
1. Epidemiology of arboviral diseases
Transmission of vector-borne pathogens is strongly affected by climate and other anthropogenic factors such as irrigation and land use change. These processes are dynamic, and my research focuses on a mechanistic understanding of the heterogeneous processes that drive transmission of these pathogens. Specific research questions focus on the causes of outbreaks of arboviral diseases and the factors that allow them to persist between years. Several recent research projects from our lab have focused on the epidemiology of dengue with Dr. Amy Morrison, PhD student Anna Kawiecki, and Dr. Tom Scott (Elson, Kawiecki, et al. 2022. BMC Public Health, 22(1): 1924; Lambrechts et al. 2023. PLoS Negl Trop Dis, 17(9):e0011593; Morrison et al. 2023. PLoS ONE, 18(2): e0273798). Collectively, these studies have expanded methods for large-scale field trials and our knowledge of the role of humans in the dynamics of DENV transmission, including evidence from mosquitoes feeding on DENV-infected volunteers to understand infectiousness during early stages of illness when patients are more mobile and less aware of their infection. Our lab is also a part of the NIH-funded EpiCenter for Emerging Infectious Disease Intelligence in Peru and Uganda, and we collaborate with Dr. Amy Morrison and Dr. Valerie Paz-Soldan (Tulane University) on implementation science for community-based dengue control in Iquitos, Peru.
2. Evaluation of control strategies for reducing vector-borne diseases
There is a pressing need for field evaluations of control strategies to reduce vector-borne diseases. This is a new and growing area of my research that is supported by two grants. One is an NIH-funded R01 with Brian Foy at Colorado State University to evaluate distribution of ivermectin to wild birds via backyard feeders as a means for controlling WNV. Mosquitoes die shortly after biting birds fed on ivermectin-coated feed, which provides a candidate method for interrupting local transmission cycles in urban environments without the need to spray insecticides over wider areas. Former PhD student Karen Holcomb has published two important papers from this project, the first on our field trial in backyard chickens (Holcomb et al. 2022. PLoS Negl Trop Dis, 16(3): e0010260), and the second being a simulation study to understand potential impacts of the wild bird strategy under different scenarios for effectiveness and spatial coverage (Holcomb et al. 2023. Epidemics, 44: 100697). This work has guided our ongoing 2024-2025 field trials in Davis, CA and Fort Collins, CO that are evaluating the ivermectin strategy in wild birds. Other major efforts have focused on evaluating control strategies for the DENV vector, Aedes aegypti, and we have published a study showing the household-level effects of insecticide treatments for Aedes aegypti led by PhD student Anna Kawiecki in collaboration with Dr. Amy Morrison (Kawiecki et al. 2024. Parasites & Vectors, 17: 254).
3. Modeling and prediction to guide public-health actions for vector-borne diseases
Public-health priorities continue to shape my research and service, especially the interests of California stakeholders, including CDPH and local mosquito and vector control agencies throughout the state. Much of my work aims to answer timely, policy-relevant questions that inform public-health decisions, and I have worked closely with public-health partners to evaluate California’s surveillance program for arboviruses and to develop response guidelines and risk models. Examples of our work in this area are an evaluation of the predictive value of the California response plan’s risk model for predicting human WNV disease risk (Danforth et al. 2022. PLoS Negl Trop Dis, 16(5): e0010375), an evaluation of national forecasts for WNV disease with CDC (Holcomb et al. 2023. Parasites & Vectors, 16: 11), and other forthcoming manuscripts in development with post-doc Aynaz Lotfata and CDC from this body of work.