More Like this

1. The paradoxical impact of drought on West Nile virus risk: insights from long-term ecological data

   https://doi.org/10.1098/rspb.2025.1365  

   Sambado, Samantha; Sipin, Terrell J; Rennie, Zoe; Larsen, Ashley; Cunningham, James; Quandt, Amy; Sousa, Dan; MacDonald, Andrew J (September 2025, Proceedings of the Royal Society B: Biological Sciences)

   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. 

   more » « less
2. Not all mosquitoes are created equal: A synthesis of vector competence experiments reinforces virus associations of Australian mosquitoes

   https://doi.org/10.1371/journal.pntd.0010768  

   Kain, Morgan P.; Skinner, Eloise B.; Athni, Tejas S.; Ramirez, Ana L.; Mordecai, Erin A.; van den Hurk, Andrew F. (October 2022, PLOS Neglected Tropical Diseases)

   Brackney, Doug E. (Ed.)

   The globalization of mosquito-borne arboviral diseases has placed more than half of the human population at risk. Understanding arbovirus ecology, including the role individual mosquito species play in virus transmission cycles, is critical for limiting disease. Canonical virus-vector groupings, such as Aedes - or Culex -associated flaviviruses, have historically been defined using virus detection in field-collected mosquitoes, mosquito feeding patterns, and vector competence, which quantifies the intrinsic ability of a mosquito to become infected with and transmit a virus during a subsequent blood feed. Herein, we quantitatively synthesize data from 68 laboratory-based vector competence studies of 111 mosquito-virus pairings of Australian mosquito species and viruses of public health concern to further substantiate existing canonical vector-virus groupings and quantify variation within these groupings. Our synthesis reinforces current canonical vector-virus groupings but reveals substantial variation within them. While Aedes species were generally the most competent vectors of canonical “ Aedes -associated flaviviruses” (such as dengue, Zika, and yellow fever viruses), there are some notable exceptions; for example, Aedes notoscriptus is an incompetent vector of dengue viruses. Culex spp. were the most competent vectors of many traditionally Culex -associated flaviviruses including West Nile, Japanese encephalitis and Murray Valley encephalitis viruses, although some Aedes spp. are also moderately competent vectors of these viruses. Conversely, many different mosquito genera were associated with the transmission of the arthritogenic alphaviruses, Ross River, Barmah Forest, and chikungunya viruses. We also confirm that vector competence is impacted by multiple barriers to infection and transmission within the mesenteron and salivary glands of the mosquito. Although these barriers represent important bottlenecks, species that were susceptible to infection with a virus were often likely to transmit it. Importantly, this synthesis provides essential information on what species need to be targeted in mosquito control programs. 

   more » « less
3. Extreme climate whiplash events drive divergent responses of mosquito-borne disease

   https://doi.org/10.1093/pnasnexus/pgaf223  

   MacDonald, Andrew J; Sousa, Dan; Quandt, Amy; Sambado, Samantha; Sipin, Terrell J; Rennie, Zoe; Larsen, Ashley E (July 2025, PNAS Nexus)

   Campbell, Corey; Brenner, David (Ed.)

   Abstract There is mounting concern surrounding climate change effects on human health. Vector-borne diseases—transmitted by ectotherms like mosquitos—are sensitive to abiotic conditions, and there is a significant interest in modeling their response to future climate change. However, changing climate also contributes to increasing variability and frequency of extreme weather, including “climate whiplash” events, when weather conditions abruptly shift between extremes. These events may have more immediate effects on vector-borne diseases, though they have received less attention. Here, we use the series of extreme atmospheric rivers of 2022/2023 in California, following years of extreme drought, as a natural experiment to assess the effect of climate whiplash on vector-borne disease risk. Using high spatiotemporal resolution standing water remote sensing, mosquito and viral surveillance, and community science observations of key reservoir hosts, we estimate mosquito species- and virus-specific responses to flooding following atmospheric rivers using panel regression models. We find significant positive effects of flooding on abundance of the rural West Nile virus (WNV) vector in California's Central Valley, with the largest effects at landscape scales. We find no significant effects for the urban WNV vector, or globally invasive yellow fever mosquito. Finally, we find similarly divergent effects on WNV and Saint Louis Encephalitis virus (SLEV) infection: WNV rates decline significantly in the urban vector and SLEV increases significantly in the rural vector. These results reveal species-specific responses to climate whiplash that are predictable by mosquito ecology, relevant to globally important mosquito vectors and diseases, and inform public health response to future extreme events. 

   more » « less
4. Remote sensing of temperature‐dependent mosquito and viral traits predicts field surveillance‐based disease risk

   https://doi.org/10.1002/ecy.4420  

   MacDonald, Andrew J; Hyon, David; Sambado, Samantha; Ring, Kacie; Boser, Anna (November 2024, Ecology)

   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. 

   more » « less
5. The Arbovirus Mapping and Prediction (ArboMAP) system for West Nile virus forecasting

   https://doi.org/10.1093/jamiaopen/ooad110  

   Nekorchuk, Dawn M; Bharadwaja, Anita; Simonson, Sean; Ortega, Emma; França, Caio_M B; Dinh, Emily; Reik, Rebecca; Burkholder, Rachel; Wimberly, Michael C (January 2024, JAMIA Open)

   Abstract ObjectivesWest Nile virus (WNV) is the most common mosquito-borne disease in the United States. Predicting the location and timing of outbreaks would allow targeting of disease prevention and mosquito control activities. Our objective was to develop software (ArboMAP) for routine WNV forecasting using public health surveillance data and meteorological observations. Materials and MethodsArboMAP was implemented using an R markdown script for data processing, modeling, and report generation. A Google Earth Engine application was developed to summarize and download weather data. Generalized additive models were used to make county-level predictions of WNV cases. ResultsArboMAP minimized the number of manual steps required to make weekly forecasts, generated information that was useful for decision-makers, and has been tested and implemented in multiple public health institutions. Discussion and ConclusionRoutine prediction of mosquito-borne disease risk is feasible and can be implemented by public health departments using ArboMAP. 

   more » « less