Tick Dermacentor Variabilis Research Articles

386. Pathogen-Harboring Ticks are Prevalent in Suburban Green Spaces in Central North Carolina

Abstract Background North Carolina (NC) reports high numbers of ehrlichiosis and spotted fever group rickettsioses. However, the prevalence of pathogens in ticks has historically been relatively low, with a < 10% prevalence of Ehrlichia spp. and < 1% prevalence of Rickettsia rickettsii in field-collected Amblyomma americanum and Dermacentor variabilis ticks. Most entomological surveys have focused on woodlands and rural sites, while less is known about the risk of human-tick interactions in suburban green spaces such as parks.Table 1.Pathogens identified in ticks in central North Carolina from surveillance in suburban green spaces and animal shelters. Methods The objective of the study, which was supported by an IDSA GERM Award, was to describe the prevalence and distribution of pathogen-harboring ticks in a suburban area of central NC with a focus on green spaces. Tick surveillance was performed by dragging vegetation in 16 suburban green spaces, primarily city and county parks, in Orange and Chatham Counties from June - August 2022. Ticks were also collected from stray dogs presenting to two county animal shelters. Polymerase chain reaction (PCR) was used to detect pathogens in the ticks. Results A total of 107 ticks were collected and underwent PCR testing (Table 1), including 40 collected via dragging and 67 from animal shelters. A. americanum were the most frequently encountered ticks, accounting for more than two-thirds of ticks collected in green spaces and half of ticks from shelters. A total of 26% were positive for E. chaffeensis or E. ewingii, with substantially higher infection rates among ticks from shelters. A. maculatum accounted for 25% of ticks in green spaces, half of which were positive for R. parkeri. The vast majority (90%) of D. variabilis ticks were collected from shelters, but all three ticks from green spaces were positive for R. rickettsii. While of uncertain pathogenicity, R. amblyommatis was the most frequently encountered bacterium among all ticks collected. Conclusion Our findings demonstrate that pathogen-infected ticks are present in suburban green spaces. Given that exposure risk of tick-borne disease is commonly associated with rural activities such as hiking, camping, and hunting, further education and public campaigns are warranted, and vector control efforts may need to be considered. Our findings also suggest that A. maculatum may be moving further inland than previously reported. Disclosures All Authors: No reported disclosures

Detection of Anaplasma bovis-like agent in the Southcentral United States

Anaplasma bovis is primarily an infectious agent of ruminants, and has most commonly been reported in Asia, the Middle East, and Africa. Although the primary cause of human anaplasmosis is Anaplasma phagocytophilum, humans may rarely be infected by other Anaplasma spp. Human disease attributed to A. bovis has been occasionally reported, including an A. bovis-like agent in the United States. DNA of an A. bovis-like agent has been amplified from humans and the tick Dermacentor variabilis in the central region of the U.S., but larger prevalence studies among potential vectors or reservoir hosts in the U.S. have not been reported. The aim of this study was to evaluate the prevalence of A. bovis-like agent among D. variabilis and cattle in the Southcentral U.S. Previously extracted DNA from adult D. variabilis collected from Oklahoma (n = 38) and Kansas (n = 93), and blood of cattle from Oklahoma (n = 140) were tested by conventional PCR. Overall prevalence of A. bovis-like DNA within ticks was determined to be 3.1% (4/131), and all positive ticks originated from Oklahoma. Overall prevalence in bovine blood was determined to be 0% (0/140). These findings confirm the presence of an A. bovis-like agent, a potentially zoonotic pathogen, among ticks in the Southcentral U.S.; this agent is likely underrecognized and has been detected in parts of the U.S. that lie outside of the established geographic range for A. phagocytophilum. Further investigation and surveillance are necessary to elucidate possible reservoirs of A. bovis in the U.S., further evaluate the burden of human infection, and fully characterize genetic differences between the A. bovis-like agent detected in the U.S. and A. bovis in other regions of the world.

Surveillance of tick-borne pathogens present in ticks (Acari: Ixodidae) removed from companion animals in Louisiana, USA.

Current knowledge of tick distribution and tick-borne pathogen presence across Louisiana is limited. Collaborating with veterinarians across the state, ticks removed from companion animals were recovered and assessed for the presence of zoonotic pathogens. A large number of ticks (n = 959) were removed from companion animals and subsequently screened using qPCR for Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi, Bartonella henselae, Ehrlichia chaffeensis, and spotted fever group Rickettsia. Five different tick species, Ixodes scapularis (54.5%), Amblyomma americanum (18.4%), Amblyomma maculatum (12.5%), Dermacentor variabilis (11.2%), and Rhipicephalus sanguineus (0.3%) from different regions of Louisiana were collected from October 2018 to July 2019. There were 15 PCR-positive ticks for Rickettsia parkeri (1.6% prevalence), and four ticks were positive for Ehrlichia chaffeensis (0.4% prevalence). This survey identifies ticks and tick-borne pathogens associated with companion animals and areas for future active surveillance.

WITHDRAWN: Detection of Amblyomma maculatum and Rickettsia parkeri in prairies of Central Missouri

Prairie habitats are complex ecosystems experiencing destruction and decline due to landscape repurposing, thus resulting in significant changes to plant, animal, and insect wildlife diversity. In the Central United States, the reconstruction of prairie habitats from farmland is a widely applied strategy to raise diversity and recreate a healthy, complex ecosystem. In Central Missouri, we are examining the consequences of reconstruction efforts on the prevalence of zoonotic diseases and their associated pathogens and have observed large populations of Dog ticks, Dermacentor variabilis, and Lone Star ticks, Amblyomma americanum, as well as the first recorded instance of the Gulf Coast tick, Amblyomma maculatum, in Callaway County. The Gulf Coast tick is traditionally found mainly along the Atlantic and Gulf Coast regions, but has been undergoing geographic expansion in the last decade. Since detection in 2020, the number of Gulf Coast ticks has increased,. Upon screening 193 Gulf Coast ticks in 105 pools, we found that 6.67 % of ticks were positive for the pathogenic Rickettsia parkeri, which causes spotted fever rickettsiosis in animals and humans, with most ticks coming from the reconstructed prairie site. These observations suggest that reconstruction of prairie habitat has the potential to support the sylvatic cycle of Rickettsia parkeri. Collectively, our observations show that the reconstructed prairie are capable of harboring large tick populations as compared to remnant prairies and demonstrates a potential increase in disease risk as a result. This works highlights the importance of proactive surveillance of ticks, especially with land-use change.

Exposure of American Black Bears (Ursus americanus) to Ticks, Tick-Borne Diseases, and Intestinal Parasites in Wisconsin

We surveyed 159 American black bears (Ursus americanus) over a period of three years for the occurrence of ticks, tick-borne diseases, and intestinal parasites in Wisconsin. We collected blood from the bears to test for the presence of antibodies to Borrelia burgdorferi (Lyme disease), Rickettsia rickettsii (Rocky Mountain spotted fever (RMSF)), Babesia, Ehrlichia, Ehrlichia canis, Brucella canis, and Anaplasma phagocytophilum. We also examined scat samples for intestinal parasites. We commonly found the tick Dermacentor variabilis, but also present the first report of Rhipicephalus sanguineus on black bears. We detected antibodies to Lyme disease and RMSF. We detected antibodies to E. canis for the first time in a bear and both antibodies to R. rickettsii and A. phagocytophilum for the first time in a black bear in Wisconsin. No antibodies for Babesia or Br. canis were detected. We found eggs of the intestinal parasite Baylasascaris transfuga as well as a low number of Toxascara leonina and unknown Capillaria species occurrences in the examined feces.

Molecular Detection of Pathogenic Bacteria in American Dog Ticks (Dermacentor variabilis) in Brown County, Nebraska

Molecular Detection of Pathogenic Bacteria in American Dog Ticks (Dermacentor variabilis) in Brown County, Nebraska

Differences in the reproductive output and larval survival of Rocky Mountain wood ticks (Dermacentor andersoni) and American dog ticks (Dermacentor variabilis) from prairie populations near their northern distributional limits in western Canada.

The effects of temperature and relative humidity (RH) on female reproductive output, egg development and larval survival were determined for Rocky Mountain wood ticks (Dermacentor andersoni) from a prairie population (Chin Lakes, Alberta, Canada) near the northern distribution limit of this species. The responses of D. andersoni eggs and unfed larvae to different temperature (25 or 32°C) and RH (35, 55, 75, 85 or 95%) regimes were compared to our previously published data (Diyes et al. 2021) for a northern prairie population of American dog ticks (Dermacentor variabilis). Oviposition by D. andersoni females took 21-30 days at 25°C and 95% RH compared to 10-21 days for D. variabilis. The number of eggs laid by female ticks was strongly dependent on their engorgement weight, and D. andersoni females produced more eggs than D. variabilis females of an equivalent body weight. Eggs of D. andersoni took less time to develop at 32°C than 25°C with ≥ 85% RH, and hatched faster than those of D. variabilis. Larval survival times declined as temperature increased and RH decreased, but D. andersoni survived longer at 32°C and ≤ 75% RH than D. variabilis. The interspecific differences in responses to the same temperature and humidity regimes indicate that D. andersoni is xerophilic, whereas D. variabilis is hydrophilic. Hence, 'prairie' populations of the Rocky Mountain wood tick occur in the drier grassland ecoregions but are absent in Aspen Parklands Ecoregion which is located to the north and east of the distributional range of D. andersoni.

Describing the experience of livestock producers from Ohio, USA with ticks and associated diseases

BackgroundAs tick ranges expand across North America, the risk of tick bites and tick-borne diseases (TBDs, i.e. diseases or syndromes associated with ticks) rises for humans and animals, making prevention critical. Several U.S. studies have examined knowledge, attitudes, and practices regarding ticks and TBDs for various cohorts of people. However, among occupational groups with high exposure risk from ticks and TBDs are livestock producers, of which we know little about. To help address this gap, an electronic questionnaire was distributed to livestock producers in Ohio, U.S, a state with a robust agricultural sector.MethodsWe generated descriptive statistics and conducted a multiple correspondence analysis followed by hierarchical clustering on principal components to identify producers with similar response profiles.ResultsResponses from 57 producers showed that most (52.6%) think the American dog tick (Dermacentor variabilis) is found in Ohio but are unsure about other species. Although several TBDs are present in Ohio, most (> 50%) producers were unsure or unaware of their presence. Interestingly, most (54.4%) thought ticks pose major health risks for their livestock but fewer (49.1%) thought the same for humans. Regardless, most producers did employ at least one prevention method for themselves (96.5%) and their animals (82.5%). Cluster analysis (n = 48) identified three groups: the largest (n = 21) was considered “aware and cautious” consisting primarily of farm owners. The others generally practiced less prevention and consisted primarily of farm employees.ConclusionsOur findings indicate that producers in Ohio practice prevention for themselves and their livestock, but demonstrate gaps in knowledge (e.g., TBD occurrence) and attitudes (e.g., health risks) that could be addressed via educational formats we found producers preferred (e.g., extension materials), to encourage informed prevention. This is especially important for farm employees that may practice less prevention because of lower awareness. Our study can guide others in regions faced with similar tick and TBD risks to protect occupational and livestock health.

Survival of adult Amblyomma americanum, Amblyomma maculatum, and Dermacentor variabilis (Acari: Ixodidae) in four habitats in southeastern Virginia.

Adult, unfed Amblyomma americanum (Linnaeus), Amblyomma maculatum Koch, and Dermacentor variabilis (Say) ticks were housed inside environmental containers in situ from May through August 2015. The environmental containers were placed in 4 habitats in southeastern Virginia, United States. Two of the habitats were located in low ground and were prone to flooding; the other two consisted of a drier landscape located in a more upland habitat. A Cox Regression survival analysis indicated there was a significant difference in survival among species across all field sites. There was a 50.5-times higher risk of mortality for A. maculatum compared to A. americanum, a 4.3-times higher risk of mortality for A. maculatum compared to D. variabilis, and an 11.9-times higher risk of mortality for D. variabilis compared to A. americanum. There was also significantly higher mortality in field sites prone to flooding than in drier, upland field sites. We concluded that A. americanum was not negatively affected by increased flooding or the variable environmental conditions in southeastern Virginia. Dermacentor variabilis also was successful at remaining in the environment off-host, although increased flooding reduced survival over time. Amblyomma maculatum was more susceptible to mortality during long periods of time off-host in both environments, with high mortality rates in both dry upland and low-ground, flood-prone habitats.

A citizen science approach to investigate the distribution, abundance, and pathogen infection of vector ticks through active surveillance

Tick-borne disease poses a growing public health burden in the United States and understanding the patterns of presence and density of infected vector ticks is key to developing and implementing effective public health management strategies. Citizen science has emerged as a highly effective means to generate data sets on the geographical distribution of tick species. But to date, nearly all citizen science studies of ticks are ‘passive surveillance’ programs in which researchers accept reports of ticks, together with either physical specimens or digital images, found opportunistically on people, pets, and livestock from community members for species identification and in some cases also tick-borne pathogen detection. These studies are limited because data are not collected systematically, making comparisons among locations and over time challenging, and introducing considerable reporting bias. In this study, we engaged citizen scientists in ‘active surveillance’ of host-seeking ticks, training volunteers to actively collect ticks on their woodland properties in an emergent region of tick-borne disease in the state of Maine, USA. We developed volunteer recruitment strategies, materials to train volunteers in data collection methods, field data collection protocols based on techniques used by professional scientists, and a variety of incentives to promote volunteer retention and satisfaction with their experiences, and we communicated research findings to participants. A total of 125 volunteers in 2020 and 181 volunteers in 2021 collected 7,246 ticks in southern and coastal Maine, including the American dog tick (Dermacentor variabilis, 4,023 specimens), the blacklegged tick (Ixodes scapularis, 3,092 specimens), and the rabbit tick (Haemaphysalis leporispalustris, 102 specimens). We demonstrated the feasibility of citizen scientists collecting ticks using active surveillance methods and found that volunteers were motivated to participate largely by their interest in the scientific problem and a desire to learn about ticks on their properties.

Common yarrow (Achillea millefolium) essential oil and main components as potential repellents and acaricides against Ixodes scapularis and Dermacentor variabilis (Acari: Ixodidae) ticks.

Repellent and acaricidal activities of essential oils (EO) extracted from common yarrow (Achillea millefolium L.) and main chemical components were evaluated against Ixodes scapularis and Dermacentor variabilis adult ticks and nymphs. Flowers and leaves were collected from two locations, Harvest Moon trail (HMT) and Port Williams (PW) in Nova Scotia (Canada), and EO were extracted via hydro-distillation. Samples were analyzed using GC-MS, and differences in chemical composition and quantity of compounds detected were reported in relation to the collection site and plant parts. EO were both rich in germacrene D (HMT EO 21.5 ± 1.31% wt; PW EO 25.5 ± 0.76% wt); however, HMT flower EO has a higher concentration of camphor (9.9 ± 0.08% wt) compared to PW flower EO (3.0 ± 0.01% wt). Significant acaricidal activity was reported against I. scapularis adult ticks, particularly for HMT flower EO with a LD50 of 2.4% v/v (95% confidence interval = 1.74-3.35) at 24h post-exposure. Germacrene D had the lowest LD50 of 2.0% v/v (95% CI 1.45-2.58) among the four compounds after 7 days. No significant acaricidal effect was observed on D. variabilis adult ticks. Yarrow PW flower EO exerted repellent activity towards I. scapularis nymphs (100% repellency up to 30min); however, repellency significantly declined over time. Yarrow EO exert promising acaricidal and repellent properties, that may be used to manage Ixodes ticks and the diseases they vector.

Mitochondrial Genomes of the American Dog Tick (Dermacentor variabilis) Isolated from Horses in the Midwestern United States.

Here, we report two complete and three partial mitochondrial genome sequences of Dermacentor variabilis specimens collected from horses in the United States. The complete genomes are 14,837 bp long and contain 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. The sequences have been deposited under GenBank accession numbers ON052120 to ON052124.

A novel laboratory method to simulate climatic stress with successful application to experiments with medically relevant ticks.

Ticks are the most important vectors of zoonotic disease-causing pathogens in North America and Europe. Many tick species are expanding their geographic range. Although correlational evidence suggests that climate change is driving the range expansion of ticks, experimental evidence is necessary to develop a mechanistic understanding of ticks’ response to a range of climatic conditions. Previous experiments used simulated microclimates, but these protocols require hazardous salts or expensive laboratory equipment to manipulate humidity. We developed a novel, safe, stable, convenient, and economical method to isolate individual ticks and manipulate their microclimates. The protocol involves placing individual ticks in plastic tubes, and placing six tubes along with a commercial two-way humidity control pack in an airtight container. We successfully used this method to investigate how humidity affects survival and host-seeking (questing) behavior of three tick species: the lone star tick (Amblyomma americanum), American dog tick (Dermacentor variabilis), and black-legged tick (Ixodes scapularis). We placed 72 adult females of each species individually into plastic tubes and separated them into three experimental relative humidity (RH) treatments representing distinct climates: 32% RH, 58% RH, and 84% RH. We assessed the survival and questing behavior of each tick for 30 days. In all three species, survivorship significantly declined in drier conditions. Questing height was negatively associated with RH in Amblyomma, positively associated with RH in Dermacentor, and not associated with RH in Ixodes. The frequency of questing behavior increased significantly with drier conditions for Dermacentor but not for Amblyomma or Ixodes. This report demonstrates an effective method for assessing the viability and host-seeking behavior of tick vectors of zoonotic diseases under different climatic conditions.

Tick-Borne Pathogens in Questing Blacklegged Ticks (Acari: Ixodidae) From Pike County, Pennsylvania.

Active surveillance was conducted by collecting questing ticks from vegetation through a 2-yr survey in Pike County, Pennsylvania. Over a thousand blacklegged ticks (Ixodes scapularis Say) and American dog ticks (Dermacentor variabilis Say) were collected. A single specimen of the following species was collected: lone star tick (Amblyomma americanum L.), rabbit tick (Haemaphysalis leporispalustris Packard), and an Asian longhorned tick (Haemaphysalis longicornis Neumann). This study represents the largest county-wide study in Pennsylvania, surveying 988 questing I. scapularis adult and nymphs. Molecular detection of five distinct tick-borne pathogens was screened through real-time PCR at a single tick resolution. Respectively, the overall 2-yr adult and nymph prevalence were highest with Borrelia burgdorferi (Spirochaetales: Spirochaetacceae) (45.99%, 18.94%), Anaplasma phagocytophilum (Rickettsiales: Anaplasmataceae) (12.29%, 7.95%) where the variant-ha (8.29%, 3.03%) was overall more prevalent than the variant-v1 (2.49%, 4.17%), Babesia microti (Piroplasmida: Babesiidae) (4.97%, 5.30%), Borrelia miyamotoi (Spirochaetales: Spirochaetaceae) (1.38%, 1.89%), and Powassan virus lineage II [POWV]/deer tick virus (DTV) (2.07%, 0.76%). Adult and nymph coinfection prevalence of B. burgdorferi and B. microti (3.03%, 4.97%) and adult coinfection of B. burgdorferi and A. phagocytophilum or A. phagocytophilum and B. microti were significantly higher than the independent infection rate expected naturally. This study highlights the urgency to conduct diverse surveillance studies with large sample sizes to better understand the human risk for tick-borne diseases within small geographical areas.

Influence of tick sex and geographic region on the microbiome of Dermacentor variabilis collected from dogs and cats across the United States

As tick-borne diseases continue to increase across North America, current research strives to understand how the tick microbiome may affect pathogen acquisition, maintenance, and transmission. Prior high throughput amplicon-based microbial diversity surveys of the widespread tick Dermacentor variabilis have suggested that life stage, sex, and geographic region may influence the composition of the tick microbiome. Here, adult D. variabilis ticks (n = 145) were collected from dogs and cats from 32 states with specimens originating from all four regions of the United States (West, Midwest, South, and Northeast), and the tick microbiome was examined via V4-16S rRNA gene amplification and Illumina sequencing. A total of 481,246 bacterial sequences were obtained (median 2924 per sample, range 399–11,990). Fifty genera represented the majority (>80%) of the sequences detected, with the genera Allofrancisella and Francisella being the most abundant. Further, 97%, 23%, and 5.5% of the ticks contained sequences belonging to Francisella spp., Rickettsia spp., and Coxiella spp., respectively. No Ehrlichia spp. or Anaplasma spp. were identified. Co-occurrence analysis, by way of correlation coefficients, between the top 50 most abundant genera demonstrated five strong positive and no strong negative correlation relationships. Geographic region had a consistent effect on species richness with ticks from the Northeast having a significantly greater level of richness. Alpha diversity patterns were dependent on tick sex, with males exhibiting higher levels of diversity, and geographical region, with higher level of diversity observed in ticks obtained from the Northeast, but not on tick host. Community structure, or beta diversity, of tick microbiome was impacted by tick sex and geographic location, with microbiomes of ticks from the western US exhibiting a distinct community structure when compared to those from the other three regions (Northeast, South, and Midwest). In total, LEfSe (Linear discriminant analysis Effect Size) identified 18 specific genera driving these observed patterns of diversity and community structure. Collectively, these findings highlight the differences in bacterial diversity of D. variabilis across the US and supports the interpretation that tick sex and geographic region affects microbiome composition across a broad sampling distribution.

The role of cofeeding arthropods in the transmission of Rickettsia felis.

Rickettsia felis is an emerging etiological agent of rickettsioses worldwide. The cosmopolitan cat flea (Ctenocephalides felis) is the primary vector of R. felis, but R. felis has also been reported in other species of hematophagous arthropods including ticks and mosquitoes. Canines can serve as a bacteremic host to infect fleas under laboratory conditions, yet isolation of R. felis from the blood of a vertebrate host in nature has not been realized. Cofeeding transmission is an efficient mechanism for transmitting rickettsiae between infected and uninfected fleas; however, the mechanism of transmission among different orders and classes of arthropods is not known. The potential for R. felis transmission between infected fleas and tick (Dermacentor variabilis) and mosquito (Anopheles quadrimaculatus) hosts was examined via cofeeding bioassays. Donor cat fleas infected with R. felis transmitted the agent to naïve D. variabilis nymphs via cofeeding on a rat host. Subsequent transstadial transmission of R. felis from the engorged nymphs to the adult ticks was observed with reduced prevalence in adult ticks. Using an artificial host system, An. quadrimaculatus exposed to a R. felis-infected blood meal acquired rickettsiae and maintained infection over 12 days post-exposure (dpe). Similar to ticks, mosquitoes were able to acquire R. felis while cofeeding with infected cat fleas on rats infection persisting in the mosquito for up to 3 dpe. The results indicate R. felis-infected cat fleas can transmit rickettsiae to both ticks and mosquitoes via cofeeding on a vertebrate host, thus providing a potential avenue for the diversity of R. felis-infected arthropods in nature.

The Roof Rat, Rattus rattus, in Virginia

We collected a single specimen of Rattus rattus (Roof Rat) in Highland County, VA, a previously unknown locality for the species. We collected ecto- and endoparasites, including the louse Polyplax spinulosa, the tick Dermacentor variabilis (American Dog Tick), and the nematode Aspicularis americana. which we archived along with the host voucher specimen. Sequencing of the mitochondrial cytochrome b gene confirmed the rodent species identification based on comparisons to R. rattus sequences available in the GenBank database. Herein we review specimen records of Roof Rats and Rattus norvegicus (Brown Rat). Both species have a deep history in Virginia, but Roof Rats appear to have declined in coastal cities, while Brown Rats have become more common in those areas. Roof Rats apparently persist in rural relictual populations such as that identified in Highland County.

Testing a multi‐factorial model of the role of Rhipicephalus sanguineus in the spread of Rocky Mountain Spotted Fever in the Arizona region

Rocky Mountain Spotted Fever (RMSF) is the deadliest tick‐borne disease in the United States. RMSF is spread from a canine host to humans through incidental contact with a tick vector. Historically, transmission of R. rickettsii, the causative agent, has been associated with the American dog tick (Dermacentor variabilis) and the Rocky Mountain wood tick (Dermacentor andersoni). However, in 2003, an outbreak of RMSF in Arizona was associated with a novel vector, the brown dog tick (Rhipicephalus sanguineus). Since then, the vectoring capacity of the brown dog tick has spread across the American Southwest and into parts of Mexico. Currently, the brown dog tick is not known to vector the bacteria outside of this area despite brown dog ticks being present in every state in the U.S. If this vectoring capacity continues to expand, many parts of the country will be at risk due to the brown dog tick’s ubiquitous nature. This is especially alarming as failure to treat RMSF in humans within the first five days of infection can lead to mortality rates as high as 80%. Therefore, this research was aimed at determining the factors that are currently limiting the vectoring capacity of the brown dog tick to Arizona and the surrounding region in order to prevent further spread of RMSF.The results of our research show that the current spread of RMSF in the Arizona region is due to a combination of four factors: (1) the presence of a distinct population of brown dog ticks, (2) variation in the genetic strain of the causative agent R. rickettsii, (3) distribution of canine seroprevalence across the region, and (4) geographic and climatic factors. In support of this, we have identified three genetically distinct clades of brown dog tick across the region that vary in the R. rickettsii infection rate. In sequencing intergenic regions of the R. rickettsii isolated from these tick populations, we have identified variation in the rickettsial strain across the region. Using immunofluorescence assays, we determined that canine seroprevalence rates are rising and seropositive dogs were found in regions that have previously not reported any human cases including regions as far north as Petaluma, CA. Even more concerning, 14 of 16 counties surveyed were at medium to high risk for human outbreak. These data were then analyzed at a county level and the relative role of each of the factors varied by geographic location. Together, this multi‐factorial model is a first step towards understanding the epidemiology of RMSF in the Arizona region and provides insights into ways to improve human and canine health by stopping future spread of RMSF.

Behavioral ecology of Ixodes scapularis and the implications for Lyme disease

The most common ticks in West Virginia include the American dog tick (Dermacentor variabilis), the blacklegged tick (Ixodes scapularis), and the brown dog tick (Rhipicephalus sanguineus ( (WVU extension). One of the most common tick-borne diseases in WV is Lyme disease, caused by the spirochete Borrelia burgdorferi. Ixodes scapularis is a carrier for the B burgdorferi pathogen. Therefore, species identification is vital. The purpose of this research is to understand how tick behavior can affect the transmission and distribution of Lyme disease in the eastern United States, specifically in West Virginia. An ethogram was constructed to display five core behaviors of Ixodes scapularis.Other behaviors may appear in the ethogram but those remain variable across species and were not included. No other behaviors distinctive to Ixodes scapularis were found. 
 Five main behaviors were noted in Ixodes scapularis and can be functionally applied to other tick species. By understanding the behavior of ticks, the knowledge can be used to understand the prevalence of tick distribution in the eastern United States. When combining tick behavior and its distribution, one can then focus on the prevalence of Borrelia burgdorferi in infected ticks. Additionally, infected tick behavior can differ from uninfected ticks, resulting in more frequent questing and biting behaviors. Different populations of the same species can also differ in questing height and hiding behavior.

Repellent and acaricidal activities of basil (Ocimum basilicum) essential oils and rock dust against Ixodes scapularis and Dermacentor variabilis ticks.

Repellent and acaricidal activity of essential oils extracted from three varieties of basil (Ocimum basilicum L.) were evaluated on blacklegged ticks (Ixodes scapularis Say) and American dog ticks (Dermacentor variabilis Say) in laboratory conditions. Essential oils were extracted and characterized through gas chromatography-mass spectrometry, and tested at different concentrations for long-term repellent activity using horizontal bioassays. In addition, basil essential oils were combined with an inert material (i.e., granite rock dust) with known insecticidal and miticidal properties to assess acaricidal activities against adult ticks. Among the tested basil varieties, var. Jolina essential oil at 15% vol/vol concentration repelled 96% of tested ticks up to 2h post-treatment. The EC50 for I. scapularis nymphs was 4.65% vol/vol (95% confidence interval: 4.73-4.57). In acaricidal tests, the combination of essential oil from var. Aroma 2 at 10% wt/wt with rock dust resulted in 100% tick mortality after only 24h post-exposure, with a LD50 of 3.48% wt/wt (95% CI 4.05-2.91) for freshly prepared treatment tested on I. scapularis adults. The most common compounds detected in basil essential oils by GC-MS were linalool (52.2% in var. Nu Far, 48.2% in Aroma 2, 43.9% in Jolina), sabinene (6.71% in Nu Far, 8.99% in Aroma 2, 8.11% in Jolina), eugenol (11.2% in Jolina, 8.71% in Aroma 2), and estragole (18.2% in Nu Far). The use of essential oils alone and in combination with rock dust provides an innovative and environmentally friendly approach for managing ticks and inhibiting vector-borne disease transmission.