Impact of Unexplored Data Sources on the Historical Distribution of Three Vector Tick Species in Illinois

Methods of active surveillance for hard ticks and associated tick-borne pathogens of public health importance in the contiguous United States: a comprehensive systematic review

Tick-borne diseases in humans and animals have increased prevalence across the United States. To understand risk factors underlying tick-borne diseases it is useful to conduct regular surveillance and monitoring of ticks and the pathogens they carry, in a sustained and effective manner. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, this study aims to summarize the previously used methods for active surveillance of ticks and tick-borne pathogens, identify the existing knowledge gaps in ongoing surveillance, and highlight and guide the mechanisms required to inform those gaps for more effective and sustainable future surveillance efforts. After screening 2,500 unique studies between 1944 and 2018, we found 646 articles that performed active surveillance of hard ticks and/or their associated tick-borne pathogens of public health importance within the United States. An additional 103 articles were included for the 2019 to 2023 period. Active surveillance has been performed in ~42% of the counties (1944 to 2018) and ~23% of the counties (2019 to 2023) within the contiguous US, and states with the most coverage are in the Northeast, Upper Midwest, and along the West coast. The most reported tick was Ixodes scapularis (195 studies) and most commonly reported pathogen was Borrelia burgdorferi (143 studies). Overall, surveillance efforts have increased and become more diversified, and methods of tick and tick-borne pathogens testing have undergone changes, but those efforts are mainly concentrated in focal regions of a county. Future surveillance efforts should follow Centers for Disease Control and Prevention guidelines and target areas of United States with scarce reports of active surveillance and build collaborations and resources to increase surveillance.

Perspectives from federal and state public health departments on their participation in and the utility of Ixodes scapularis (Acari: Ixodidae) and Ixodes pacificus tick and tick-borne pathogen surveillance in the United States

In response to notable increases in tick-associated illnesses in the United States, recent public health policies encouraged multi-sector collaborative approaches to preventing vector-borne diseases. Primary prevention strategies focus on educating the public about risks for tick-borne diseases and encouraging adoption of personal protection strategies. Accurate descriptions of when and where people are at risk for tick-borne diseases aid in the optimization of prevention messaging. Tick and tick-borne pathogen data can be used to fill gaps in epidemiological surveillance. However, the utility of acarological data is limited by their completeness. National maps showing the distribution of medically important tick species and the pathogens they carry are often incomplete or non-existent. Recent policies encourage accelerated efforts to monitor changes in the distribution and abundance of medically important ticks and the presence and prevalence of human pathogens that they carry, and to provide actionable, evidence-based information to the public, health care providers and public health policy makers. In 2018, the Centers for Disease Control and Prevention initiated a national tick surveillance program focused on Ixodes ticks. The national program coordinated and expanded upon existing efforts led by public health departments and academic institutions. Here, we describe experiences of state public health departments engaged in Ixodes tick surveillance, including information on why they initiated Ixodes surveillance programs, programmatic objectives, and strategies for maintaining tick surveillance programs. We share experiences and challenges in interpreting or communicating tick surveillance data to stakeholders and explore how the acarological data are used to complement epidemiological data.

Assessing knowledge gaps and empowering Extension workers in Illinois with information on ticks and tickborne diseases through KAP surveys

Tickborne diseases (TBDs) are increasingly prevalent in Illinois and the Upper Midwest region. People who work in occupations that require time outdoors in agricultural or natural settings, such as some Extension workers, are at risk of tick bites and TBDs. Additionally, Extension workers are often a primary source of information about ticks and TBDs in rural communities. However, there is limited information on the level of awareness about ticks and TBDs in the Extension community. The goals of this study were to sequentially i) determine the baseline awareness of Extension workers in Illinois about ticks and TBDs using a knowledge, attitudes, and practices (KAP) survey tool, ii) provide comprehensive training on ticks and TBDs to this demographic, and iii) measure the uptake of knowledge after the training intervention through a post-training survey. The study period was from June 2022 until May 2023. We received 233 pre-training and 93 paired post-training survey responses. Most survey respondents were Extension volunteers, identified as women, and were over 50 years old. Knowledge about ticks and TBDs varied. We identified several gaps in their current tick awareness, most importantly, in tick prevention measures, tick identification, and TBDs in general. TBD knowledge, attitude, and practice scores all significantly improved after training (p < 0.001), with a mean difference of 10.47, 1.49, and 2.64 points, respectively. Additionally, both Extension professionals (79.2 %) and Extension volunteers (66.7 %) were more likely to feel confident in engaging with their stakeholders on ticks and TBDs after participating in training. Poisson models revealed that higher attitude and practice scores and greater self-reported knowledge were the factors most significantly associated with higher TBD knowledge. We found that greater concern for ticks and TBD (attitudes) and adherence to science-based prevention and management methods (practices) were also associated with higher knowledge scores. To our knowledge, this is the first study in Illinois to capture Extension workers' awareness of ticks and TBDs. The results highlight Extension workers' interest in filling knowledge gaps through learning, and the importance of training Extension workers to disseminate reliable and updated information on ticks and TBDs to their constituents, a critical step in preventing TBDs.

Changes in the geographic distribution of the blacklegged tick, Ixodes scapularis, in the United States

Ixodes scapularis (the blacklegged tick) was considered a species of no medical concern until the mid-1970s. By that time, the tick's geographic distribution was thought to be mainly in the southeastern United States (US), with additional localized populations along the Eastern Seaboard north to southern Massachusetts and in the Upper Midwest. Since 1975, I. scapularis has been implicated as a vector of seven human pathogens and is now widely distributed across the eastern US up to the border with Canada. Geographic expansion of tick-borne diseases associated with I. scapularis (e.g., Lyme disease, anaplasmosis, and babesiosis) is attributed to an expanding range of the tick. However, due to changes in tick surveillance efforts over time, it is difficult to differentiate between range expansion and increased recognition of already established tick populations. We provide a history of the documented occurrence of I. scapularis in the US from its description in 1821 to present, emphasizing studies that provide evidence of expansion of the geographic distribution of the tick. Deforestation and decimation of the white-tailed deer (Odocoileus virginianus), the primary reproductive host for I. scapularis adults, during the 1800s presumably led to the tick disappearing from large areas of the eastern US where it previously had been established. Subsequent reforestation and deer population recovery, together with recent climate warming, contributed to I. scapularis proliferating in and spreading from refugia where it had persisted into the early 1900s. From documented tick collection records, it appears I. scapularis was present in numerous locations in the southern part of the eastern US in the early 1900s, whereas in the north it likely was limited to a small number of refugia sites during that time period. There is clear evidence for established populations of I. scapularis in coastal New York and Massachusetts by 1950, and in northwestern Wisconsin by the late 1960s. While recognizing that surveillance for I. scapularis increased dramatically from the 1980s onward, we describe multiple instances of clearly documented expansion of the tick's geographic distribution in the Northeast, Upper Midwest, and Ohio Valley regions from the 1980s to present. Spread and local population increase of I. scapularis, together with documentation of Borrelia burgdorferi sensu stricto in host-seeking ticks, was universally followed by increases in Lyme disease cases in these areas. Southward expansion of northern populations of I. scapularis, for which the host questing behavior of the nymphal stage leads to substantially higher risk of human bites compared with southern populations, into Virginia and North Carolina also was followed by rising numbers of Lyme disease cases. Ongoing surveillance of ticks and tick-borne pathogens is essential to provide the data needed for studies that seek to evaluate the relative roles of land cover, tick hosts, and climate in explaining and predicting geographic expansion of ticks and tick-borne diseases.

Farmers' Knowledge and Practices About Ticks and Tickborne Diseases in Illinois

OBJECTIVE

Tickborne diseases (TBDs) in Illinois have increased in recent years. A growing body of literature indicates that the risk of exposure to ticks and tickborne diseases is higher among outdoor workers, including farmers. However, information is lacking on awareness of ticks and tickborne diseases among this demographic. This study aimed to determine the knowledge and awareness among Illinois farmers regarding ticks and tickborne diseases.

METHODS

A Knowledge, Attitudes & Prevention practices (KAP) survey was developed and administered to capture information regarding farmers' knowledge and attitudes about ticks and TBDs. Tick drags were conducted on a subset of properties as an incentive to complete the survey and to compare farmers' knowledge or expectations of ticks on their land with ticks collected.

RESULTS

Fifty farmers participated in the survey, and 17 allowed tick drags. Only 60% of respondents had at least moderate knowledge about ticks gained through family and friends (56%), medical and healthcare personnel (48%), and the internet (44%). Responses varied by the type of commodity produced by the farmer. Fifty percent of participants reported knowledge about the blacklegged tick, 34% for the American dog tick, and 42% for the lone star tick; this knowledge also varied by farm type. Most farmers (54%) agreed that preventative behaviors could protect against tickborne diseases. Self-reported knowledge was significantly and directly associated with knowledge scores (p < .001).

CONCLUSION

Knowledge of ticks and TBDs was lower among crop farmers than beef or mixed commodity farmers, but farmers generally have moderate knowledge of tick species in Illinois. Many participants expressed low concern over contracting a TBD, but many were also dissatisfied with the level of tick prevention measures that they follow. These results can be utilized to fill in knowledge gaps and develop informational materials to help farmers protect themselves against ticks and TBDs.

Current and Future Habitat Suitability Models for Four Ticks of Medical Concern in Illinois, USA

The greater U.S. Midwest is on the leading edge of tick and tick-borne disease (TBD) expansion, with tick and TBD encroachment into Illinois occurring from both the northern and the southern regions. To assess the historical and future habitat suitability of four ticks of medical concern within the state, we fit individual and mean-weighted ensemble species distribution models for Ixodes scapularis, Amblyomma americanum, Dermacentor variabilis, and a newly invading species, Amblyomma maculatum using a variety of landscape and mean climate variables for the periods of 1970-2000, 2041-2060, and 2061-2080. Ensemble model projections for the historical climate were consistent with known distributions of each species but predicted the habitat suitability of A. maculatum to be much greater throughout Illinois than what known distributions demonstrate. The presence of forests and wetlands were the most important landcover classes predicting the occurrence of all tick species. As the climate warmed, the expected distribution of all species became strongly responsive to precipitation and temperature variables, particularly precipitation of the warmest quarter and mean diurnal range, as well as proximity to forest cover and water sources. The suitable habitat for I. scapularis, A. americanum, and A. maculatum was predicted to significantly narrow in the 2050 climate scenario and then increase more broadly statewide in the 2070 scenario but at reduced likelihoods. Predicting where ticks may invade and concentrate as the climate changes will be important to anticipate, prevent, and treat TBD in Illinois.

Knowledge, attitudes, and practices of Illinois medical professionals related to ticks and tick-borne disease

Background

The rising incidence of tick-borne disease (TBD) underscores the importance of proficiency in TBD diagnosis. Clinicians' knowledge about vector ticks and TBDs in their area may influence whether patients are questioned about potential tick exposure and the consideration of diagnostic testing for TBDs.

Objective

Our objective was to assess the knowledge, attitudes, and practices of Illinois clinicians towards ticks and TBDs. The study aimed to 1) identify predictors associated with knowledge, 2) identify knowledge gaps, and 3) evaluate attitudes and practices related to TBDs.

Methods

A web-based knowledge, attitudes, and practices survey about Illinois ticks and TBDs was disseminated to physicians, mid-level practitioners, and nurses between August 2020 and February 2022. Poisson regression analysis was conducted to identify predictors of higher scores.

Results

Of 346 respondents, 80% correctly identified Lyme disease as endemic to Illinois, and 95% were familiar with diagnostic testing for Lyme. Knowledge of other TBDs present in the state was highest among physicians, yet only 26% of physicians believed Rocky Mountain spotted fever (RMSF) to be present in Illinois, and only 17% believed ehrlichiosis to be endemic. Only 32% of physicians knew the cause of Alpha-gal syndrome and fewer than 18% were aware of available diagnostic testing. Tick or TBD-related education within the past two years was the most significant predictor of higher scores, increasing overall knowledge scores by 26% (RR 1.26, 95% CI 1.13-1.41) and increasing scores specific to TBDs by 42% (RR 1.42, 95% CI 1.19-1.69).

Conclusion

Illinois clinicians were informed about Lyme disease but lacked knowledge of other TBDs endemic to the state, including RMSF, ehrlichiosis, and Alpha-gal syndrome. The strongest predictor of knowledge was tick/TBD training in the previous two years, highlighting the importance of frequent region-specific training on ticks and TBDs.

Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southwestern Michigan

Amblyomma americanum (Linnaeus) (Acari: Ixodidae) (lone star tick) is an aggressive, generalist parasite that vectors numerous important human and animal pathogens. In recent decades its geographic range has expanded northwards from endemic regions in the southeastern and southcentral United States. In 2019 five questing A. americanum ticks, comprising two life stages were detected at one site in southwestern Michigan, satisfying one CDC criterium for an established population for the first time in recent history in the state. To better characterize the extent of emerging A. americanum, we conducted active surveillance (i.e., drag sampling) in summer 2020 throughout Michigan's southern counties and detected one adult A. americanum from each of six widespread sites, including where they had been detected in 2019. A larger established population was identified at another site in Berrien County, which yielded 691 A. americanum comprising three life stages, and questing phenologies here were similar to that reported for other endemic regions. Statewide surveillance in 2021 revealed no A. americanum outside of Berrien County, but establishment criteria were met again at the two sites where established populations were first detected respectively in 2019 and 2020. These observations may represent the successful invasion of A. americanum into Michigan. Data from passive (1999-2020) and active surveillance (2004-2021) efforts, including a domestic animal sentinel program (2015-2018), are reported to provide context for this nascent invasion. Continued active surveillance is needed to help inform the public, medical professionals, and public health officials of the health risks associated with this vector.

A Scoping Review of Species Distribution Modeling Methods for Tick Vectors

Background

Globally, tick-borne disease is a pervasive and worsening problem that impacts human and domestic animal health, livelihoods, and numerous economies. Species distribution models are useful tools to help address these issues, but many different modeling approaches and environmental data sources exist.

Objective

We conducted a scoping review that examined all available research employing species distribution models to predict occurrence and map tick species to understand the diversity of model strategies, environmental predictors, tick data sources, frequency of climate projects of tick ranges, and types of model validation methods.

Design

Following the PRISMA-ScR checklist, we searched scientific databases for eligible articles, their references, and explored related publications through a graphical tool (www.connectedpapers.com). Two independent reviewers performed article selection and characterization using a priori criteria.

Results

We describe data collected from 107 peer-reviewed articles that met our inclusion criteria. The literature reflects that tick species distributions have been modeled predominantly in North America and Europe and have mostly modeled the habitat suitability for Ixodes ricinus (n = 23; 21.5%). A wide range of bioclimatic databases and other environmental correlates were utilized among models, but the WorldClim database and its bioclimatic variables 1–19 appeared in 60 (56%) papers. The most frequently chosen modeling approach was MaxEnt, which also appeared in 60 (56%) of papers. Despite the importance of ensemble modeling to reduce bias, only 23 papers (21.5%) employed more than one algorithm, and just six (5.6%) used an ensemble approach that incorporated at least five different modeling methods for comparison. Area under the curve/receiver operating characteristic was the most frequently reported model validation method, utilized in nearly all (98.9%) included studies. Only 21% of papers used future climate scenarios to predict tick range expansion or contraction. Regardless of the representative concentration pathway, six of seven genera were expected to both expand and retract depending on location, while Ornithodoros was predicted to only expand beyond its current range.

Conclusion

Species distribution modeling techniques are useful and widely employed tools for predicting tick habitat suitability and range movement. However, the vast array of methods, data sources, and validation strategies within the SDM literature support the need for standardized protocols for species distribution and ecological niche modeling for tick vectors.

Knowledge, attitudes, and practices of veterinary professionals towards ticks and tick-borne diseases in Illinois

Objective

A lack of standardized surveillance or reporting of tick-borne diseases (TBDs) in Illinois creates uncertainty for veterinarians regarding TBDs occurring within their practice geography or which TBDs may be encroaching on their area from neighboring territories. Therefore, the objective of this study was to gauge the knowledge, attitudes, and practices of veterinary professionals in Southern and Central Illinois to establish a foundation for targeting educational and outreach programs that address knowledge gaps.

Sample

72 veterinary professionals in Central and Southern Illinois.

Procedures

An online knowledge, attitudes, and practices survey was distributed to veterinary professionals in Southern and Central Illinois. Poisson regression analyses were conducted to determine factors associated with knowledge scores and the estimated number of TBD cases diagnosed.

Results

Knowledge scores were significantly higher among veterinary practitioners with recent (within the last 5 years) training on TBD. The number of cases of TBD diagnosed was higher among those reporting concern about TBD, and among those who routinely test for TBDs. The types of diseases diagnosed were heavily influenced by the diagnostic method used.

Clinical relevance

This study paints a cohesive picture of human factors associated with diagnosing veterinary diseases and TBD prevalence in Southern and Central Illinois. Our results highlight the importance and practical value of veterinary continuing education on ticks and TBDs for both companion animals and public health. Building capacity for training veterinarians in parasitology using partnerships between academia and industry may strengthen the knowledge and understanding of ticks and tick-borne pathogens in the veterinary community.

Effects of Climate on the Variation in Abundance of Three Tick Species in Illinois

The range of ticks in North America has been steadily increasing likely, in part, due to climate change. Along with it, there has been a rise in cases of tick-borne disease. Among those medically important tick species of particular concern are Ixodes scapularis Say (Acari: Ixodidae), Dermacentor variabilis Say (Acari: Ixodidae), and Amblyomma americanum Linneaus (Acari: Ixodidae). The aim of this study was to determine if climate factors explain existing differences in abundance of the three aforementioned tick species between two climatically different regions of Illinois (Central and Southern), and if climate variables impact each species differently. We used both zero-inflated regression approaches and Bayesian network analyses to assess relationships among environmental variables and tick abundance. Results suggested that the maximum average temperature and total precipitation are associated with differential impact on species abundance and that this difference varied by region. Results also reinforced a differential level of resistance to desiccation among these tick species. Our findings help to further define risk periods of tick exposure for the general public, and reinforce the importance of responding to each tick species differently.

Effects of tick surveillance education on knowledge, attitudes, and practices of local health department employees

BACKGROUND

The number of cases of tick-borne diseases in humans is increasing rapidly within Illinois. The responsibility for increased surveillance of tick-borne disease cases and tick vectors is being placed on local health departments throughout the United States, but they often lack the funding, time, and/or training needed to perform said surveillance. The aims of this study were to develop, deliver, and determine the effectiveness of tick surveillance training workshops for local health department employees within Illinois.

METHODS

We developed and delivered in-person training at local health department offices in each of six Illinois Department of Public Health Environmental Health Regions between April-May of 2019. Pre-, post-, and six-month follow-up questionnaires on knowledge, attitudes, and practices with regards to tick surveillance were administered to training participants. Paired student's t-test or Wilcoxon signed-rank test were used to compare knowledge, attitudes, and practices scores between questionnaires with Cohen's d being used to calculate effect sizes associated with t-tests. McNemar's and McNemar-Bowker tests were used to evaluate individual questions. Spearman's rank correlation was used to evaluate the relationship between knowledge, attitudes, and practices at pre-, post-, and six-month follow-up.

RESULTS

Seventy-six employees from 40 local health departments that represent 44% (45/102) of Illinois counties attended at least one training workshop. Of these attendees, 81.5% (62/76) participated in at least one survey, 79% (60/76) in the in-person pre-training survey, 74% (56/76) in the in-person post-training survey, and 22% (17/76) in the online six-month follow-up survey. The average knowledge score was significantly increased by 8.21 (95% CI:7.28-9.14) points from pre-training to post-training. The average overall attitude score significantly increased by 5.29 (95% CI: 3.91-6.66) points from pre- to post-training. There were no significant differences in practice scores.

CONCLUSIONS

Our study found the training was effective in increasing the knowledge of ticks, tick-borne diseases, and surveillance as well as promoting positive attitudes related to surveillance. While the training, by itself, was not associated with increases in surveillance practices, we were able to empower local public health officials with the knowledge and positive attitudes needed to enact change.

A Survey of Tick Surveillance and Control Practices in the United States

Tickborne diseases are an increasing public health threat in the United States. Prevention and diagnosis of tickborne diseases are improved by access to current and accurate information on where medically important ticks and their associated human and veterinary pathogens are present, their local abundance or prevalence, and when ticks are actively seeking hosts. The true extent of tick and tickborne pathogen expansion is poorly defined, in part because of a lack of nationally standardized tick surveillance. We surveyed 140 vector-borne disease professionals working in state, county, and local public health and vector control agencies to assess their 1) tick surveillance program objectives, 2) pathogen testing methods, 3) tick control practices, 4) data communication strategies, and 5) barriers to program development and operation. Fewer than half of respondents reported that their jurisdiction was engaged in routine, active tick surveillance, but nearly two-thirds reported engaging in passive tick surveillance. Detection of tick presence was the most commonly stated current surveillance objective (76.2%). Most of the programs currently supporting tick pathogen testing were in the Northeast (70.8%), Upper and Central Midwest (64.3%), and the West (71.4%) regions. The most common pathogens screened for were Rickettsia spp. (Rickettsiales: Rickettsiaceae) and bacterial and viral agents transmitted by Ixodes (Acari: Ixodidae) ticks. Only 12% of respondents indicated their jurisdiction directly conducts or otherwise financially supports tick control. Responses indicated that their ability to expand the capacity of tick surveillance and control programs was impeded by inconsistent funding, limited infrastructure, guidance on best practices, and institutional capacity to perform these functions.

Comparing Contributions of Passive and Active Tick Collection Methods to Determine Establishment of Ticks of Public Health Concern Within Illinois

In Illinois, between 1990 and 2017, tick-borne diseases in humans increased 10-fold, yet we have insufficient information on when and where people are exposed to vector ticks (Ixodida: Ixodidae). The aims of our research were to compare contributions of passive and active tick collection methods in determining establishment of ticks of public health concern and obtain information on tick distributions within Illinois. We used three surveillance strategies within the Illinois Tick Inventory Collaboration Network to gather information about the ticks of public health concern: 1) passive collection (voluntary submission by the public); 2) systematic collection (biweekly active surveillance); and 3) special collections (active collections in locations of special interest). Of collected adult and nymphal ticks, 436 were from passive collections, 142 from systematic collections, and 1,270 from special collections. Tick species distribution status changed in 36 counties. Our data provide noteworthy updates to distribution maps for use by public health agencies to develop prevention and control strategies. Additionally, the program built a network of collaborations and partnerships to support future tick surveillance efforts within Illinois and highlighted how the combination of the three surveillance strategies can be used to determine geographic spread of ticks, pinpoint locations in need of more surveillance, and help with long-term efforts that support phenology studies.

Impact of Land Use Changes and Habitat Fragmentation on the Eco-epidemiology of Tick-Borne Diseases

The incidence of tick-borne diseases has increased in recent decades and accounts for the majority of vector-borne disease cases in temperate areas of Europe, North America, and Asia. This emergence has been attributed to multiple and interactive drivers including changes in climate, land use, abundance of key hosts, and people's behaviors affecting the probability of human exposure to infected ticks. In this forum paper, we focus on how land use changes have shaped the eco-epidemiology of Ixodes scapularis-borne pathogens, in particular the Lyme disease spirochete Borrelia burgdorferi sensu stricto in the eastern United States. We use this as a model system, addressing other tick-borne disease systems as needed to illustrate patterns or processes. We first examine how land use interacts with abiotic conditions (microclimate) and biotic factors (e.g., host community composition) to influence the enzootic hazard, measured as the density of host-seeking I. scapularis nymphs infected with B. burgdorferi s.s. We then review the evidence of how specific landscape configuration, in particular forest fragmentation, influences the enzootic hazard and disease risk across spatial scales and urbanization levels. We emphasize the need for a dynamic understanding of landscapes based on tick and pathogen host movement and habitat use in relation to human resource provisioning. We propose a coupled natural-human systems framework for tick-borne diseases that accounts for the multiple interactions, nonlinearities and feedbacks in the system and conclude with a call for standardization of methodology and terminology to help integrate studies conducted at multiple scales.

Tick and Tickborne Pathogen Surveillance as a Public Health Tool in the United States

In recent decades, tickborne disease (TBD) cases and established populations of medically important ticks have been reported over expanding geographic areas, and an increasing number of tickborne bacteria, viruses, and protozoans have been recognized as human pathogens, collectively contributing to an increasing burden of TBDs in the United States. The prevention and diagnosis of TBDs depend greatly on an accurate understanding by the public and healthcare providers of when and where persons are at risk for exposure to human-biting ticks and to the pathogens these ticks transmit. However, national maps showing the distributions of medically important ticks and the presence or prevalence of tickborne pathogens are often incomplete, outdated, or lacking entirely. Similar deficiencies exist regarding geographic variability in host-seeking tick abundance. Efforts to accurately depict acarological risk are hampered by lack of systematic and routine surveillance for medically important ticks and their associated human pathogens. In this review, we: 1) outline the public health importance of tick surveillance; 2) identify gaps in knowledge regarding the distributions and abundance of medically important ticks in the United States and the presence and prevalence of their associated pathogens; 3) describe key objectives for tick surveillance and review methods appropriate for addressing those goals; and 4) assess current capacity and barriers to implementation and sustainability of tick surveillance programs.

Landscape features predict the current and forecast the future geographic spread of Lyme disease

Lyme disease, the most prevalent vector-borne disease in North America, is increasing in incidence and geographic distribution as the tick vector, Ixodes scapularis, spreads to new regions. We re-construct the spatial-temporal invasion of the tick and human disease in the Midwestern US, a major focus of Lyme disease transmission, from 1967 to 2018, to analyse the influence of spatial factors on the geographic spread. A regression model indicates that three spatial factors-proximity to a previously invaded county, forest cover and adjacency to a river-collectively predict tick occurrence. Validation of the predictive capability of this model correctly predicts counties invaded or uninvaded with 90.6% and 98.5% accuracy, respectively. Reported incidence increases in counties after the first report of the tick; based on this modelled relationship, we identify 31 counties where we suspect I. scapularis already occurs yet remains undetected. Finally, we apply the model to forecast tick establishment by 2021 and predict 42 additional counties where I. scapularis will probably be detected based upon historical drivers of geographic spread. Our findings leverage resources dedicated to tick and human disease reporting and provide the opportunity to take proactive steps (e.g. educational efforts) to prevent and limit transmission in areas of future geographic spread.