The need as indicated by stakeholders. According to the World Health Organization (WHO), around 17% of the infectious diseases reported worldwide are caused by vector-borne pathogens. In the US, outbreaks of vector-borne diseases are aided by human travel and the introduction of infected vectors into new areas. For example, in 2023, cases of locally acquired malaria were reported in Maryland, Texas, and Florida caused by Plasmodium vivax and Plasmodium falciparum, leading the US Centers for Disease Control and Prevention (CDC) to issue a national alert. Dengue outbreaks have been reported in Florida, where several serotypes of the virus have been detected in mosquitoes, increasing the risk of severe dengue (Coatsworth et al. 2022). Likewise, autochthonous transmission of leishmaniasis occurs in Texas and Oklahoma (Curtin and Aronson 2021). Expanded geographic distributions of vector-borne diseases endemic to the US, such as Lyme disease and other tick-borne diseases, have been  attributed to the spread of vectors into new locations (Eisen and Eisen 2023). According to the CDC, Lyme disease affects around 476,000 Americans each year primarily in the northeast with average treatment costs of $1,200 USD per individual (Hook et al 2022). Thus, vector-borne diseases represent an important risk and burden to the public, including farmers, forestry workers, and families living in urban, suburban, and rural areas in the US.

Invasive vector species threaten to alter the epidemiology and transmission dynamics of existing and new vector-borne diseases, and ultimately the health of humans, companion animals, wildlife, and livestock. Mosquito invaders include the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), that have become established in the southeastern US and are increasingly reported in California (Metzger et al. 2015). While Ae. albopictus is moving northward,  additional invasive mosquito species have also arrived. For example, the bush mosquito (Aedes japonicus) is a cold weather adapted species that has spread in suburban landscapes along the eastern seaboard, the northwestern US, the Florida panhandle, across the Hawaii volcanoes as well as Canada (Kaufman and Fonseca 2014, Jackson et al. 2016, Peterson et al. 2017), and the Australian Aedes notoscriptus has spread into southern California (Paterson and Campbell 2015). Over the last few years, we have witnessed the invasion and spread of the Asian longhorned tick (Haemaphysalis longicornis), which was first discovered on an Icelandic sheep in New Jersey in 2017 (Rainey et al. 2018) but was detected in archived records as far back as 2010, remaining misidentified and undetected for nearly a decade, if not longer (Beard et al. 2018). Through increased surveillance, it has since been detected in 19 states: Arkansas, Connecticut, Delaware, Georgia, Indiana, Kentucky, Maryland, Massachusetts, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, and West Virginia (USDA APHIS, October 2023). US populations of H. longicornis are parthenogenetic (clonal) and small infestations can quickly proliferate.. Although humans are not favored hosts of H. longicornis, opportunistic feeding is well documented both in the native and invasive ranges (Bickerton and Toledo 2020, Wormser et al. 2020). In East Asia, H. longicornis transmits severe fever with thrombocytopenia syndrome virus (SFTSV), an emerging human tick-borne disease recently reclassified as Dabie bandavirus (Liu et al. 2015, Luo et al. 2015, Li et al. 2021). Under laboratory conditions, US lineages of H. longicornis can transmit the closely related Heartland virus (Rainey et al. 2022a) and Powassan virus (Rainey et al. 2022b), two native pathogenic viruses emergent in parts of the US. While H. longicornis is currently not perceived as a major public health threat in the US, this status may change given the enormous densities it can reach in favorable habitats (Bickerton and Toledo 2020, Schappach et al. 2020, González et al. 2023, Rochlin et al. 2023). 

The importance of the work and consequences if not done. With few available vaccines and new pathogens  emerging at a steady rate, minimizing human exposure to disease vectors and managing vector populations remain the primary methods for reducing vector-borne disease risks. Our ability to properly control vector-borne disease threats is limited by our understanding of vector ecology, vector physiology, vector behavior, and the biology of vector-pathogen interactions. The economic impact of arthropod-borne illness is devastating. Consider Lyme disease, the most prevalent vector-borne disease in the United States. It's been calculated to impose a substantial burden on the U.S. healthcare system, ranging from $712 million to $1.3 billion each year(Adrion et al 2015). This financial strain arises from extensive doctor visits and diagnostic testing, particularly evident in the year following initial diagnosis, as persistent symptoms like fatigue, musculoskeletal pain, and memory issues demand ongoing attention and care. . The total cumulative costs of reported WNV hospitalization cases in the US from 1999 through 2012 were around $800 million USD  (about $77 million annually in today’s value after inflation adjustment; Staples et al. 2014). The estimated cost per human case of EEE is $3 million in 1995 dollars ($6.2 million after inflation adjustment; Villari et al. 1995). EEE and WNV both threaten the nation’s multi-billion-dollar equine industry. The mortality rate of horses infected with WNV is 34%; the rate for those with EEE approaches 100%. For example, in 2000, the estimated loss in New Jersey alone due to equine cases of WNV was $6 million ($11 million in 2024 value). Tourism, which increases human exposure to mosquitoes, is similarly impacted by outbreaks of mosquito-borne disease. The 2015-2017 outbreak of Zika virus, although generally mild in adults, was conclusively linked to severe birth defects, which carry a tremendous economic and emotional burden on affected families. Recent computational analyses estimate that even a mild Zika outbreak could cost the US in excess of $183 million in medical costs and productivity losses, whereas a severe outbreak could cost up to $1.2 billion.

The lessons learned from new and emerging mosquito- and tick-borne disease risks serve as an impetus for bolstering US research and translation to vector surveillance and management (Anyamba et al. 2014). Encouragingly, important advances are being made in areas that include new methods and tools for monitoring and the control of mosquitoes and ticks. However, the budgets for research and abatement programs follow a boom-and-bust cycle reactionary to emerging threats, which weakens the ability to sustain infrastructure necessary for managing vector-borne diseases (Kading et al. 2020). In a report released in early 2018, the CDC estimated that 80% of the nation’s vector control organizations lack the critical prevention and control capacities needed to combat the tripling of disease cases from mosquitoes, ticks, and sand flies reported over the past 13 years (CDC 2018). Improved sharing and coordination of research and translation to and standardization of monitoring and control tools are needed for researchers and control professionals to make informed decisions and better utilize limited resources.

The technical feasibility of the research. Our research will focus on critical gaps in our understanding of the vectors of disease agents in the U.S. These include mosquitoes, sandflies, kissing bugs, ticks, and other vectors of human pathogens. We will include research on the biology, spread, and control of other invasive vectors of regional importance. Our project will have three objectives:

1. Develop and strengthen effective surveillance and monitoring of disease vectors (mosquitoes, ticks, etc.) and their associated pathogens at local and regional scales.  Under this objective, project participants will leverage and strengthen existing surveillance programs in a coordinated fashion to yield robust comparable data across large geographic scales.


2. Determine the ecology, physiology, genetics and/or geographic and temporal distributions of historical, extant, and emerging disease vectors and the pathogens they transmit. Under changing environmental conditions, these studies will enhance our ability to predict conditions leading to the spread or emergence of existing and novel diseases of public health importance. 


3. Discover, develop, and integrate interventions to manage vector-borne pathogen transmission and pesticide resistance.  

Under each of these objectives, we have several sub-objectives to focus our project, which are described in the Methods section. Our objectives are technically feasible, but only if achieved by a coordinated team. Our team is composed of top entomologists, microbiologists, ecologists, wildlife biologists, and veterinarians who study vector and vector-borne pathogen biology, with the required experience and facilities and we are confident we can succeed with the proposed research.

The advantages of doing the work as a multistate effort. This work cannot be completed without a multistate effort. In a rapidly changing landscape, the experience and guidance of one region is critical to others. As a specific example, both Ae. aegypti and Ae. albopictus are new to California, and California abatement districts have benefited from the experience of those in the east coast states where these species are often the most common mosquito species. Conversely, researchers in Florida and Texas bring to the table experience working with populations affected with dengue and Zika, a set of skills that may be needed more broadly across the US. Finally, the biology that governs range expansion, vector competence, and ecology of different vector species will help to inform surveillance and management programs.

What the likely impacts will be from successfully completing the work. The project will build a highly collaborative network of experts to study existing and newly invasive vector species. The project will benefit all US residents by understanding, assessing, and mitigating the threat posed by arthropod vectors of health, veterinary, and wildlife importance. Our efforts will strengthen the capacity to detect and predict outbreaks of vector-borne diseases and evaluate the effectiveness of existing and novel control interventions under different environmental and social conditions. The project further provides for and encourages environmentally sound, scientifically based, and professional control by public health and pest control agencies. Our proposed research directly builds on a prior multistate project (NE 1943). Since 2019, we have met and exchanged published and unpublished results, have generated novel hypotheses from group participants and discussed coordination in research and sampling efforts. We have produced numerous accomplishments and deliverables and garnered competitive grants from newly formed collaborations. For this revision/replacement, we seek to expand our collaborative network to develop and strengthen a more coordinated region-wide and multi-state research effort.