Performing Department
(N/A)
Non Technical Summary
Awareness and concern for emerging diseases and invasive species has been increasing in the US. An invasive tick species, Haemaphysalis longicorns Neumann, also known as the Asian longhorned tick, has been reported in the U.S. since August 2017. Currently, 19 states have confirmed established populations of H. longicornis including Arkansas. H. longicornis is known to serve as a vector for many serious human and livestock diseases including Theileria orientalis ikeda genotype. T. orientalis ikeda is an emerging disease in the US which can cause serious disease in cattle with symptoms are similar to Anaplasmosis. In addition, H. longicornis is capable of exsanguinating cattle by mass feeding. It does not require mating to reproduce, resulting in high populations. Its ability to transmit T. orientalis creates a significant threat to cattle production. Theileriosis has recently caused cattle death in multiple U.S. states. . Our research team is capable of accomplishing this study to improve our understanding of the incidence of these issues. The goal of this proposed project is that assessing the prevalence of H. longicornis and T. orientalis Ikeda and evaluating host preference will improve the understanding and factors that affect the occurrence and incidence of these invasive ticks and this emerging disease. We expect that the data collected will improve the overall knowledge of this invasive tick and the emerging disease to improve prevention and biosecurity options for cattle producers.This research will generate critical data on the prevalence and distribution of an economically important invasive tick at the western-most edge of its current known introduced range in the US. Our results will also inform the risk of bovine theileriosis caused by T. orientalis Ikeda in the US. Our preliminary data demonstrate our group's ability to identify the parasite in Benton, Washington, and Independence counties of Arkansas, and we propose the tick as well as the pathogen are likely more widespread than currently documented. Ultimately, the data produced from such a study will provide opportunities to formulate epidemiologic management strategies that could be easily implemented by veterinarians, entomologists, and cattle producers. Future work will focus on further optimization of parasite and disease epidemiology to improve the prevention and risk assessment for beef cattle production in the south-central United States.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The majorgoal of the study is to provide a better picture of the range and ecology ofthe Asian long-horned tick (Haemaphysalislongicornis)and theileriosis (an emerging disease in cattle (Theileria orientalis Ikeda)) in the US. Research outcome on T. orientalis prevalence in ticks and H. longicornis host preference will provide baseline data. In collaboration with USDA-VA, this work will establish epidemiological investigations of new foci in Arkansas, and potentially neighboring states (i.e. Oklahoma and Missouri). We will use this baseline data to formulate additional longer term, competitive research proposals to answer the next series of questions such as identification of disease reservoir hosts and environmental/epidemiological aspects of disease transmission by H. longicornis.
Project Methods
Objective 1: To evaluate the prevalence of H. longicornis in Arkansas, and determine whether T. orientalis is present in introduced tick populationsSince 2017, one premise in Benton Co. and one premise in Washington Co. and one premise in Independence Co., Arkansas have been identified as positive sites for H. longicornis. To date the largest H. longicornis infestation in Arkansas occurred in Washington County, 174 beef calves were searched for ticks, and 26 animals were found to be infested with H. longicornis, averaging 1.2 ticks/animal. Active surveillance in a second university herd in Independence Co. in spring 2023 identified H. longicornis presence on 8 out of 170 sampled head. These sites serve as a focal point for further investigation.Active surveillanceWe propose to focus active surveillance efforts on Benton, Independence and Washington Co. through a "ring" surveillance strategy surrounding the three positive sites. Cattle operations in a 1.5 km radius surrounding the index sites in each county will first be identified. Three locations where permission to collect has been granted by landowners will be randomly selected for sampling. At least 20% of the herd will be sampled at each location. Additionally, environmental collections at each location will be conducted. If no H. longicornis are identified, we will expand the surveillance radius to 8 km, adding an additional sampling location (n=4) to account for the increased surveillance area. This process will repeat (increasing the surveillance radius by 5 km and adding an additional location each time) until either H. longicornis is identified, or the surveillance radius reaches the state line (for reference, the Washington Co. index site is ~19 km from Oklahoma and ~44 km from Missouri). If additional H. longicornsis-positive sites are identified through active surveillance, secondary surveillance rings (1.5 km) will be initiated from those sites.Collections will begin during the start of adult H. longicornis activity season in each year of the study (May). Cattle at each sampling location unit will be closely examined for ticks attached to their ears, neck, ventral underline, udder, and under the tail by hand. Attached ticks will be removed with fine tipped forceps and placed into a single vial containing 70% ethanol and labeled with the identification from the respective host. Within each sampling location, we will also take environmental tick collections using tick dragging and carbon dioxide trapping methods. At each university farm location, a tick drag will be utilized to sample nine 100 meter transects, and within each transect. Collected ticks will then be placed in a single 70% ethanol vial labeled with transect identification, date collected, GPS coordinates, and the farm identification. Tick drags will be performed twice per month at each location during peak tick season (May - June).Environmental tick collections will also be accomplished using tick traps in suitable tick habitats (field edges, wooded areas and grassy areas) on each university farm for a two-hour sampling period. The traps will be constructed using a 1x 1meter white cotton cloth with a 2.0-liter water cooler containing dry ice placed in the center of the cloth. This serves as an attractant to ticks, and ticks collected within the two-hour sampling period will be removed from the cloth and placed in a vial containing 70% ethanol, or the cloth can be folded and placed in a plastic zipper bag for further processing in the lab. After live animal and environmental collections are completed, upon returning to the laboratory, each tick will then be taxonomically identified to stage, sex and species.Determining the prevalence of T. orientalis Ikeda in H. longicornis - To assess the potential threat of theileriosis in Arkansas, all H. longicornis collected from cattle or from cattle pastures will be tested for T. orientalis ikeda genotype using PCR. Ticks will be laterally bisected using a sterile scalpel. One half of each tick will be used for DNA extraction and the other half will be stored in 90% ethanol at -20C. Tick DNA will be extracted using a modified HotSHOT protocol and stored at -80C until DNA amplification is performed.We will also collect blood samples opportunistically from animals exhibiting symptoms consistent with bovine theileriosis in herds that were sampled for H. longicornis. Samples will be collected into a 7 mL blood collection tube containing 7.2 mg K2 EDTA using an18-guage blood collection needle for jugular venipuncture. Collection tubes will be labeled with animal identification numbers, collection date and farm location. Immediately following collection, tubes containing blood samples will be placed in coolers containing ice packs for transport and returned to the University of Arkansas Fayetteville campus. Blood samples will be tested for T. orientalis Ikeda DNA using the same assay as for tick samples.Passive surveillanceDue to the discovery of H. longicornis in noncontiguous Arkansas counties, we suspect that this tick is currently more established across the state than is currently known. Passive surveillance methods will be used to maximize the odds of detection in areas not currently known to harbor the ticks, while minimizing labor. Tick collection kits will be distributed to CES agents in each Arkansas county. Agents will be provided with written instructions on how to collect ticks from animals and how to record the appropriate sample data for each collection. Requested data will include: County, Locality (preferably GPS coordinates), Host Species, and Collection Date. Because H. longicornis has frequently been collected from dogs and white-tailed deer in other states, tick collection kits will also be provided to veterinarians, and to Arkansas Game and Fish Commission agents during open deer season. Ticks will be identified and processed as above.Objective 2: To evaluate immature H. longicornis host preference in ArkansasHaemaphysalis longicornis is a three-host tick, meaning that each life stage (larva, nymph, adult) must locate a new host on which to feed in order to molt to the next life stage. Three-host ticks often show life stage-specific host preferences, with larvae typically feeding on smaller animals and adults feeding on larger animals. So far, H. longicornis has been collected from at least 44 mammal and 57 bird species in the US, but reptile sampling efforts have been limited, and no reports on hosts besides cattle and dogs have been made from Arkansas.?Host preferenceTo assess the host-use of immature H. longicornis in Arkansas we will conduct small mammal trapping at the Savoy Research Center (Washington Co. index site) and at the Batesville Livestock and Forestry Research Station (Independence Co. index site), specifically targeting pastures where H. longicornis has been collected from cattle and in environmental collections. Rodents will be trapped using Sherman live traps. Traps will be placed in a grid in the woods directly adjacent to pastures, using 10 traps per site. Traps will be set one night per week during the active surveillance season. Captured animals will be anesthetized with isoflurane, and a whole-body search will be performed. Reptiles will be collected across Northwest Arkansas and the Western Arkansas River Valley in wooded and open-canopy sites, specifically targeting fence lizards, skinks, and box turtles that frequently host native tick species. We will capture reptiles by hand and using natural and artificial cover. Animals will be identified to species, and whole bodies will be examined for ticks. Ticks will be removed using forceps and stored in 90% ethanol for identification to species, as in Objective 1.Data analysis/interpretationMultiple statistical methods will be used in determining H. longicornis and T. orientalis prevalence and immature H. longicornis host preference,