Deer ticks, or blacklegged ticks (top), are a common carrier for the bacteria that cause Lyme disease. Project Vector Shield researchers confirmed a Gulf Coast tick in southern Indiana in 2019 (bottom left). During one sample collection trip (bottom right), a tick was discovered clinging to the face of a white-footed mouse. Photos by USDA ARS (top), Smith Collection - Getty Images (bottom left), and the Clay Lab (bottom right)
Changes in climate and human activities contribute to the movement of disease vectors, such as ticks and mosquitoes, into new geographic regions. The only way to detect these movements is through regular, long-term monitoring and data collection. Though cases of tick- and mosquito-borne illness such as Lyme disease and West Nile virus are relatively uncommon in Indiana, reports have grown steadily in the last decade and official records likely underestimate the scope of the problem.
Beginning in 2018, IU researchers established Project Vector Shield, a long-term surveillance network for monitoring Indiana tick and mosquito populations and assessing disease risk. For three years, the team collected thousands of specimens from 10 sites located in state parks, forests, and wildlife areas near Indiana's eastern, southern, and western borders. At each site, researchers collected specimens from two types of plots—a natural plot, such as a wildlife clearing or hiking trail, where ticks may be more abundant, and a managed plot, such as a campsite or boat landing, where the risk of human exposure may be high.
With sample collection completed in 2020, the research team’s early findings show the presence of two tick species in the state is more widespread than previously recorded. Researchers found established populations of the Blacklegged tick, also known as the deer tick, in nearly every collection site. They also detected a northward expansion of the Lone Star tick, which historically has been relegated to the southernmost parts of the state. The findings could mean that more Hoosiers are at risk of contracting Lyme disease, which is transmitted to humans by Blacklegged ticks, and a host of other disease-causing bacteria and viruses.
With more analysis to be conducted, Project Vector Shield represents one of the most comprehensive multi-year surveillance efforts of arthropod-borne disease vectors ever conducted in the state, providing a current snapshot of local tick dynamics that will inform Indiana public health strategies and fill gaps in larger scientific studies focused on disease vector distribution.
Beyond identifying the geographic distribution of Indiana tick and mosquito populations, the research team is working with the IU Center for Genomics and Bioinformatics, the IU School of Medicine, and others to conduct DNA analysis and investigate the prevalence of disease-causing pathogens in vector populations. Mosquitoes from Project Vector Shield are being shared for studies examining the distribution of disease-causing viruses and other microbial agents that may inhibit mosquitoes’ abilities to carry and transmit pathogens (See the ERI project, “Assessing vector competence for Indiana mosquito populations”).
Results from these studies will provide valuable information to policymakers, researchers, and citizens on how to protect against new disease threats.
Updated March 19, 2021
Over the course of the project, Project Vector Shield collected tick and mosquito samples across multiple plots at 10 sites in the state. See below for more information on this data.
The research team collected data on the densities and dynamics of multiple tick and mosquito species across seasons for each of the 10 collection sites.
The research team sampled all locations and sites repeatedly (five to eight times per year) from the spring through the fall. Field sampling was composed of cloth drag sampling and CO2 trapping for ticks and mosquitoes. The physical samples have been processed and the research team is talking to colleagues at the IU Center for Genomics and Bioinformatics about molecular analysis and other post-collection processes. Initial laboratory analyses from Year 1 samples indicate that common tick-borne pathogens, like the agent causing Lyme disease, are present in southern Indiana.
The structure of the data elements used in this project have been derived in part from the National Ecological Observation Network (NEON) tick and mosquito protocols. For each tick sampling event in the field, the team recorded the date, time, and location, as well as environmental variables, such as temperature, relative humidity, and estimates of cloud cover and vegetation surface moisture. The team also recorded the duration of passive mosquito- and tick-trap deployments.
Field-collected tick samples are sorted to species and stage, resulting in tick density data for each sampling event. Field collected mosquito samples are identified to species, giving mosquito density data for each trapping event. Sorting and identification of ticks captured in 2020 and mosquitoes captured between 2018 and 2020 are ongoing.
The data has been formatted into a spreadsheet for numerical analyses. The research team is also developing visualizations to illustrate its findings.
The data will be made available on the ERI Data Platform and an initial manuscript on tick diversity and densities has been submitted for publication. Information about long-term preservation is forthcoming.
