Tick Abundance Research Articles

Integrated human behavior and tick risk maps to prioritize Lyme disease interventions using a 'One Health' approach

Lyme disease (LD) risk is emerging rapidly in Canada due to range expansion of its tick vectors, accelerated by climate change. The risk of contracting LD varies geographically due to variability in ecological characteristics that determine the hazard (the densities of infected host-seeking ticks) and vulnerability of the human population determined by their knowledge and adoption of preventive behaviors. Risk maps are commonly used to support public health decision-making on Lyme disease, but the ability of the human public to adopt preventive behaviors is rarely taken into account in their development, which represents a critical gap. The objective of this work was to improve LD risk mapping using an integrated social-behavioral and ecological approach to: (i) compute enhanced integrated risk maps for prioritization of interventions and (ii) develop a spatially-explicit assessment tool to examine the relative contribution of different risk factors.The study was carried out in the Estrie region located in southern Québec. The blacklegged tick, Ixodes scapularis, infected with the agent of LD is widespread in Estrie and as a result, regional LD incidence is the highest in the province. LD knowledge and behaviors in the population were measured in a cross-sectional health survey conducted in 2018 reaching 10,790 respondents in Estrie. These data were used to create an index for the social-behavioral component of risk in 2018. Local Empirical Bayes estimator technique were used to better quantify the spatial variance in the levels of adoption of LD preventive activities. For the ecological risk analysis, a tick abundance model was developed by integrating data from ongoing long-term tick surveillance programs from 2007 up to 2018. Social-behavioral and ecological components of the risk measures were combined to create vulnerability index maps and, with the addition of human population densities, prioritization index maps. Map predictions were validated by testing the association of high-risk areas with the current spatial distribution of human cases of LD and reported tick exposure. Our results demonstrated that social-behavioral and ecological components of LD risk have markedly different distributions within Estrie. The occurrence of human LD cases or reported tick exposure in a municipality was positively associated with tick density and the prioritization risk index (p < 0.001).This research is a second step towards a more comprehensive integrated LD risk assessment approach, examining social-behavioral risk factors that interact with ecological risk factors to influence the management of emerging tick-borne diseases, an approach that could be applied more widely to vector-borne and zoonotic diseases.

Seroepidemiology of Borrelia burgdorferi s.l. among German National Cohort (NAKO) Participants, Hanover.

Lyme borreliosis is the leading tick-related illness in Europe, caused by Borrelia Burgdorferi s.l. Lower Saxony, Germany, including its capital, Hanover, has a higher proportion of infected ticks than central European countries, justifying a research focus on the potential human consequences. The current knowledge gap on human incident infections, particularly in Western Germany, demands serological insights, especially regarding a potentially changing climate-related tick abundance and activity. We determined the immunoglobulin G (IgG) and immunoglobulin M (IgM) serostatuses for 8009 German National Cohort (NAKO) participants from Hanover, examined in 2014-2018. We used an enzyme-linked immunosorbent assay (ELISA) as the screening and a line immunoblot as confirmation for the Borrelia Burgdorferi s.l. antibodies. We weighted the seropositivity proportions to estimate general population seropositivity and estimated the force of infection (FOI). Using logistic regression, we investigated risk factors for seropositivity. Seropositivity was 3.0% (IgG) and 2.1% (IgM). The FOI varied with age, sharply increasing in participants aged ≥40 years. We confirmed advancing age and male sex as risk factors. We reported reduced odds for seropositivity with increasing body mass index and depressive symptomatology, respectively, pointing to an impact of lifestyle-related behaviors. The local proportion of seropositive individuals is comparable to previous estimates for northern Germany, indicating a steady seroprevalence.

Practice of integrated vector surveillance of arthropod vectors, pathogens and reservoir hosts to monitor the occurrence of tropical vector-borne diseases in 2020 in Zhejiang Province, China.

Vector-borne diseases have become one of the most serious local public health threats. Monitoring and controlling vectors are important means of controlling vector-borne diseases. However, traditional vector surveillance systems in China mainly monitor vector density, making its early-warning effect on vector-borne diseases weak. In this study, we applied an integrated surveillance system of multiple arthropod vectors and reservoir host containing ecology, etiology, and drug resistance monitoring to obtain better knowledge on vector populations and provide early warning of suspicious vector-borne infectious disease occurrence. An ecology surveillance of mosquitoes, rodents, ticks, and chigger mites, a pathogen infection survey on mosquitoes and rodents, and a drug resistance survey on Aedes albopictus were conducted in 12 cities in Zhejiang Province in 2020. A total of 15,645 adult mosquitoes were collected at a density of 19.8 mosquitoes per Centers for Disease Control and Prevention light trap. Culex tritaeniorhynchus (72.76%) was the most abundant species. The Breteau index of Ae. albopictus was 13.11. The rodent density was 0.91 rodents per hundred traps; the most abundant species was Rattus norvegicus (33.73%). The densities of dissociate and ectoparasitic ticks were 0.79 ticks per hundred meters and 0.97 ticks per animal, respectively. The most abundant tick species was Haemaphysalis longicornis (56.38%). The density of chigger mites was 14.11 per rodent; two species were identified, with the most abundant species being Walchia spp. mite (68.35%). No flavivirus or alphavirus was found in mosquito etiology monitoring, whereas the positivity rates of hantavirus, the pathogenic bacteria Leptospira spp., Orientia tsutsugamushi, and Bartonella spp. detected in rodent etiology monitoring were 1.86, 7.36, 0.35 and 7.05%, respectively. Field populations of Ae. albopictus in Zhejiang Province were widely resistant to pyrethroids but sensitive to most insecticides tested, including organophosphorus and carbamate insecticides. Integrated surveillance systems on multiple arthropod vectors (mosquitoes, ticks, mites) and animal reservoirs (rodents) can provide important information for the prevention and control of epidemic emergencies.

Prevalence of Bourbon and Heartland viruses in field collected ticks at an environmental field station in St. Louis County, Missouri, USA

Heartland and Bourbon viruses are pathogenic tick-borne viruses putatively transmitted by Amblyomma americanum, an abundant tick species in Missouri. To assess the prevalence of these viruses in ticks, we collected 2778 ticks from eight sampling sites at Tyson Research Center, an environmental field station within St. Louis County and close to the City of St. Louis, from May - July in 2019 and 2021. Ticks were pooled according to life stage and sex, grouped by year and sampling site to create 355 pools and screened by RT-qPCR for Bourbon and Heartland viruses. Overall, 14 (3.9%) and 27 (7.6%) of the pools were positive for Bourbon virus and Heartland virus respectively. In 2019, 11 and 23 pools were positive for Bourbon and Heartland viruses respectively. These positives pools were of males, females and nymphs. In 2021, there were 4 virus positive pools out of which 3 were positive for both viruses and were comprised of females and nymphs. Five out of the 8 sampling sites were positive for at least one virus. This included a site that was positive for both viruses in both years. Detection of these viruses in an area close to a relatively large metropolis presents a greater public health threat than previously thought.

Single Mowing Event Does Not Reduce Abundance of Ixodes scapularis (Acari: Ixodidae) and Dermacentor variabilis (Acari: Ixodidae) on Recreational Hiking Trails.

Nuisance and medically important ticks can be abundant in a variety of forested landscapes, including recreational parks. Strategies to reduce the abundance of host-seeking ticks in high-use areas within parks are limited. Mowing vegetation is a recommended method to control ticks, but few studies have evaluated the efficacy of this practice. The goal of this study was to determine if a single mowing event could reduce the abundance of host-seeking ticks on recreational trails. Ticks were collected by dragging trails at three recreational parks in northern Minnesota during June and July, 2021. A pre-intervention sample was taken followed by six consecutive weeks of tick sampling. We encountered a total of 3,456 ticks (2,459 Ixodes scapularis Say and 997 Dermacentor variabilis L.) during the 7-week study period. There were no significant differences in the abundance of I. scapularis (adults) or D. variabilis (adults only) between control and mown trail sections. Mowing was a significant predictor of nymphal I. scapularis abundance but trended towards more ticks in mown sections compared to controls. These results suggest that a single mowing intervention during early June is likely to be ineffective as a strategy to reduce the risk of human contacts with ticks on trails.

Longer study length, standardized sampling techniques, and broader geographic scope leads to higher likelihood of detecting stable abundance patterns in long term black-legged tick studies.

BackgroundUnderstanding how study design and monitoring strategies shape inference within, and synthesis across, studies is critical across biological disciplines. Many biological and field studies are short term and limited in scope. Monitoring studies are critical for informing public health about potential vectors of concern, such as Ixodes scapularis (black-legged ticks). Black-legged ticks are a taxon of ecological and human health concern due to their status as primary vectors of Borrelia burgdorferi, the bacteria that transmits Lyme disease. However, variation in black-legged tick monitoring, and gaps in data, are currently considered major barriers to understanding population trends and in turn, predicting Lyme disease risk. To understand how variable methodology in black-legged tick studies may influence which population patterns researchers find, we conducted a data synthesis experiment.Materials and MethodsWe searched for publicly available black-legged tick abundance dataset that had at least 9 years of data, using keywords about ticks in internet search engines, literature databases, data repositories and public health websites. Our analysis included 289 datasets from seven surveys from locations in the US, ranging in length from 9 to 24 years. We used a moving window analysis, a non-random resampling approach, to investigate the temporal stability of black-legged tick population trajectories across the US. We then used t-tests to assess differences in stability time across different study parameters.ResultsAll of our sampled datasets required 4 or more years to reach stability. We also found several study factors can have an impact on the likelihood of a study reaching stability and of data leading to misleading results if the study does not reach stability. Specifically, datasets collected via dragging reached stability significantly faster than data collected via opportunistic sampling. Datasets that sampled larva reached stability significantly later than those that sampled adults or nymphs. Additionally, datasets collected at the broadest spatial scale (county) reached stability fastest.ConclusionWe used 289 datasets from seven long term black-legged tick studies to conduct a non-random data resampling experiment, revealing that sampling design does shape inferences in black-legged tick population trajectories and how many years it takes to find stable patterns. Specifically, our results show the importance of study length, sampling technique, life stage, and geographic scope in understanding black-legged tick populations, in the absence of standardized surveillance methods. Current public health efforts based on existing black-legged tick datasets must take monitoring study parameters into account, to better understand if and how to use monitoring data to inform decisioning. We also advocate that potential future forecasting initiatives consider these parameters when projecting future black-legged tick population trends.

Statewide survey of medically important ticks on white-tailed deer, Odocoileus virginianus Zimmerman, in Alabama, U.S.A.

A statewide survey of the tick fauna found on deer, using harvested deer heads as the sample unit, was conducted during the Alabama hunting seasons of 2019-2020 and 2020-2021. Four species of ticks: Ixodes scapularis (n= 936, % of catch 69.1%), Amblyomma americanum (315, 23.2%), Dermacentor albipictus (97, 7.1%), and Amblyomma maculatum (6, 0.4%) were taken from 151 deer heads harvested from 21 deer processing centers (n = 4-17 heads/processor). A total of 87.7% (prevalence) of deer heads had one or more ticks. We used two standard numerical descriptors of tick numbers, abundance, and relative abundance. No significant stepwise regressions (p > 0.05) were found between tick abundance (all ticks, I. scapularis, A. americanum) and the predictor variables of latitude, deer density, season, and year. In addition, the correlation between the abundance of I. scapularis and A. americanum was not significant (p > 0.5). In contrast, the relative abundance of both I. scapularis and A. americanum showed a significant (P < 0.05) relationship with latitude, with the relative abundance of I. scapularis increasing on deer with increased latitude and A. americanum showing the opposite pattern.

STUDY ON TICKS REMOVED FROM PATIENTS FOR INFECTION WITH BORRELIA BURGDORFERI AND THEIR NUMBER DEPENDING ON TEMPERATURE AND PRECIPITATION IN 2016-2021

Background: Deacarization, applied epidemiological measures, and climatic factors affect the abundance of ticks. On the other hand, ticks themselves are a factor of great epidemiological and epizootic importance. Studies concerning the influence of climatic factors on ticks and their infection with B. burgdorferi are still limited in Bulgaria. The aim was to investigate the abundance of ticks in relation to temperature and precipitation, as well as the infection with B. burgdorferi of ticks removed from patients during the period 2016-2021. Materials/methods: A total of 10,907 ticks were collected from patients and classified according to species and stage of development. Nested PCR was performed targeting two sites of the spacer region between 5S and 23S of B. burgdorferi sensu lato rRNA. Weather data were collected from free Internet meteorological sites. Results: It was found that 92-96% of the ticks belonged to the species Ixodes ricinus. PCR data were obtained for infestation of ticks in 2016-2021. Only in 2018, the highest number of ticks was observed in May, while in the other five years - in June, which was analyzed in relation to the average temperature and precipitation. Conclusion: An increase in tick abundance was observed at average temperatures around 20°C, with rainfall on the days before the peak. During the 6-year period, the highest number of ticks was collected in June 2021, which could be explained with the high average temperatures and abundant precipitations during the preceeding spring months (April – June).

Importance of Host Abundance and Microhabitat in Tick Abundance.

To reduce the risk of zoonoses, it is necessary to understand the infection process, including the ecology of animals and vectors (i.e., the 'One Health' approach). In temperate climates, ticks are the major vectors of zoonoses, so factors determining their abundance, such as host mammal abundance and microhabitat conditions, should be clarified. Sika deer (Cervus nippon) are a major tick host and are rapidly expanding their distribution in Japan. We established 12 plots along a gradient of sika deer abundance in Tochigi Prefecture, Japan. We monitored the occurrence of mammal species with camera traps and sampled questing ticks on a monthly basis by flagging along three transects (center of a trail, forest edge, and forest interior) at each site from April to November 2018. The camera traps recorded 12 mammal species, predominantly sika deer. Five Haemaphysalis species and three Ixodes species were sampled. The numbers of ticks sampled were explained by the photographic frequency of sika deer, and partly by that of other mammal species, depending on tick species and their developmental stages. The numbers of sampled adult and nymphal ticks were the highest at the forest edge, where vegetation cover was greatest. Thus, vegetation management in tick habitats and the control of sika deer populations may reduce tick abundance.

Patterns of adult tick parasitization of coexisting European (Erinaceus europaeus) and Algerian (Atelerix algirus) hedgehog populations in eastern Iberia

The availability of data regarding population abundance and dynamics of ticks in wild vertebrate populations is crucial to understand the host-tick relationship and to assess the risk for domestic animals and humans from possible zoonotic diseases. In this study we analyse several host-intrinsic and environmental factors affecting the tick population of two sympatric hedgehog species (the European and the Algerian hedgehog) in two differently anthropized habitats in eastern Spain. We captured 215 hedgehogs and sampled 356 adult ticks of four different species (Rhipicephalus sanguineus, R. turanicus, R. bursa and R. pusillus). We analysed by General Linear Mixed Models how the hosts’ species, sex, capture month and site and their interactions affected tick presence and tick load. Further, we carried out Spearman correlation tests to analyse how environmental temperature and precipitation affect tick presence and load on hedgehogs. We found that, in general, male hedgehogs were more infested than females. However, the effects of the different factors depended on the tick species, especially related to their endophilic or exophilic character. High values of general tick infestation can be explained by the coincidence of tick activity peaks and higher male host activity levels, especially within areas with higher habitat diversity and species richness. We also discuss how the potential immunosuppressive effect of testosterone could be affecting our results. Our results show that in highly anthropized environments hedgehogs potentially act as important mixing vessels for tick-borne zoonotic pathogens and that monitoring ticks in periurban wildlife is important to assess potential health risks for pets and humans.

Using next generation sequencing for molecular detection and differentiation of Anaplasma phagocytophilum variants from host seeking Ixodes scapularis ticks in the United States

Anaplasmosis is increasingly common in the United States, with cases being reported over an expanding geographic area. To monitor for changes in risk of human infection, the U.S. Centers for Disease Control and Prevention monitors the distribution and abundance of host-seeking vector ticks (Ixodes scapularis and Ixodes pacificus) and their infection with Anaplasma phagocytophilum. While several variants of A. phagocytophilum circulate in I. scapularis, only the human-active variant (Ap-ha) appears to be pathogenic in humans. Failure to differentiate between human and non-human variants may artificially inflate estimates of the risk of human infection. Efforts to differentiate the Ap-ha variant from the deer variant (Ap-V1) in ticks typically rely on traditional PCR assays coupled with sequencing of PCR products. However, laboratories are increasingly turning to Next Generation Sequencing (NGS) to increase testing efficiency, retain high sensitivity, and increase specificity compared with traditional PCR assays. We describe a new NGS assay with novel targets that accurately segregate the Ap-ha variant from other non-human variants and further identify unique clades within the human and non-human variants. Recognizing that not all investigators have access to NGS technology, we also developed a PCR assay based on one of the novel targets so that variants can be visualized using agarose gel electrophoresis without the need for subsequent sequencing. Such an assay may be used to improve estimates of human risk of developing anaplasmosis in North America.

Predicting the current and future risk of ticks on livestock farms in Britain using random forest models

The most abundant tick species in northern Europe, Ixodes ricinus, transmits a range of pathogens that cause disease in livestock. As I. ricinus distribution is influenced by climate, tick-borne disease risk is expected to change in the future. The aims of this work were to build a spatial model to predict current and future risk of ticks on livestock farms across Britain. Variables relating both to tick hazard and livestock exposure were included, to capture a niche which may be missed by broader scale models. A random forest machine learning model was used due to its ability to cope with correlated variables and interactions. Data on tick presence and absence on sheep and cattle farms was obtained from a retrospective questionnaire survey of 926 farmers. The ROC of the final model was 0.80. The model outputs matched observed patterns of tick distribution, with areas of highest tick risk in southwest and northwest England, Wales, and west Scotland. Overall, the probability of tick presence on livestock farms was predicted to increase by 5–7 % across Britain under future climate scenarios. The predicted increase is greater at higher altitudes and latitudes, further increasing the risk of tick-borne disease on farms in these areas.

Environmental factors driving fine-scale ixodid tick abundance patterns

Tick abundance is an essential demographic parameter to infer tick-borne pathogen transmission risks. Spatiotemporal patterns of tick abundance are heterogeneous, so its determinants at small spatial scales need to be understood to reduce their negative effects on hosts. Current knowledge of these determinants is scarce, especially in Mediterranean environments, limiting the possibilities for designing efficient tick control strategies. With the goal of unravelling tick abundance determinants and informing new tick management strategies, we estimated tick burdens on 1965 wild ungulates in Doñana National Park, Spain, annually between 2010 and 2020. Under the hypothesis of a predominant host influence on tick abundance, we modelled the burdens of Rhipicephalus annulatus, Hyalomma lusitanicum, and Ixodes ricinus with relevant predictors grouped into four factors: i) environment; ii) host population; iii) host individual; and iv) land-use. Generalized linear mixed models with a zero-inflated negative binomial distribution were built. Additionally, we analysed the differential contribution to abundance of each factor by deviance partitioning. We finally estimated the similarity in the environmental space of tick species by analysing their niche overlap with the environmental principal component analysis method. Our work hypothesis was confirmed for R. annulatus and H. lusitanicum, but we found that tick abundance at a fine spatial scale is jointly driven by multiple drivers, including all four factors considered in this study. This result points out that understanding the demography of ticks is a complex multifactorial issue, even at small spatial scales. We found no niche differences between the three tick species at the study spatial scale, thus showing similar host and environmental dependencies. Overall results identify that host aggregation areas displaying environmentally favourable traits for ticks are relevant tick and vector-borne pathogen transmission hotspots. Our findings will facilitate the design of new strategies to reduce the negative effects of tick parasitism.

No net effect of host density on tick-borne disease hazard due to opposing roles of vector amplification and pathogen dilution.

To better understand vector‐borne disease dynamics, knowledge of the ecological interactions between animal hosts, vectors, and pathogens is needed. The effects of hosts on disease hazard depends on their role in driving vector abundance and their ability to transmit pathogens. Theoretically, a host that cannot transmit a pathogen could dilute pathogen prevalence but increase disease hazard if it increases vector population size. In the case of Lyme disease, caused by Borrelia burgdorferi s.l. and vectored by Ixodid ticks, deer may have dual opposing effects on vectors and pathogen: deer drive tick population densities but do not transmit B. burgdorferi s.l. and could thus decrease or increase disease hazard. We aimed to test for the role of deer in shaping Lyme disease hazard by using a wide range of deer densities while taking transmission host abundance into account. We predicted that deer increase nymphal tick abundance while reducing pathogen prevalence. The resulting impact of deer on disease hazard will depend on the relative strengths of these opposing effects. We conducted a cross‐sectional survey across 24 woodlands in Scotland between 2017 and 2019, estimating host (deer, rodents) abundance, questing Ixodes ricinus nymph density, and B. burgdorferi s.l. prevalence at each site. As predicted, deer density was positively associated with nymph density and negatively with nymphal infection prevalence. Overall, these two opposite effects canceled each other out: Lyme disease hazard did not vary with increasing deer density. This demonstrates that, across a wide range of deer and rodent densities, the role of deer in amplifying tick densities cancels their effect of reducing pathogen prevalence. We demonstrate how noncompetent host density has little effect on disease hazard even though they reduce pathogen prevalence, because of their role in increasing vector populations. These results have implications for informing disease mitigation strategies, especially through host management.

VIRAL DETECTION IN TICKS AND THE LEVEL OF TICKS’ INFESTATIONS AMONGST SMALL RUMINANTS IN MAIDUGURI, BORNO STATE

Ticks were the first arthropods to be established as vectors of pathogens and are currently recognized, along with mosquitoes, as the main arthropod vectors of disease agents to humans and domestic animals globally due to increased incidences of tick-borne diseases (TBDs) the world over. They are responsible for the transmission of many viral diseases to humans and domestic animals. Therefore, ticks infection and infestation results in great economic losses to resource-poor farming communities, especially in tropical and subtropical regions, including Nigeria, where approximately 80% of the world’s cattle population is raised. The current study is aimed to study the distribution, composition and abundance of ticks in Maiduguri, Borno State. Adult ticks were collected from 350 freshly butchered small ruminants (sheep and goats) from three locations within Maiduguri metropolis namely:Kasuwa shanu, Bulumkutu, and Maiduguri Central Abattoir. These were identified using taxonomy identification keys in to three species, Rhipicephalus, Amblyomma and Hyalomma, using stereomicroscope for each of the locations. They were crushed using bullet blender after the addition of glass beads and centrifuged. The supernatant from the crushed samples was used for viral detection by inoculating it on to two cell lines, Baby Hamster Kidney (BHK) and African Monkey Kidney (Vero E6), and were observed for cytopathic effects daily for a period of ten (10) days. The results showed a high level of ticks’ infestation amongst small ruminants in the study locations. Kasuwan Shanu has the highest distribution of ticks amongst sheep, followed by Maiduguri Central Abattoir while Bulumkutu has the least. More also, Kasuwan Shanu has the highest distribution of ticks amongst goats, followed by Bulumkutu while Maiduguri Central Abbatoir has the least. The three species of ticks investigated were found to comprise of either male or female or both in the different locations, and either of the two sexes is involved in the infestation. The results also showed the presence of virus in some of the tick samples isolated from the small ruminants andinoculated on to the cell lines due to the observed cytopathic effects. It is concluded that there is high level of ticks’ infestation among small ruminants in Maiduguri metropolis and a threat of viral disease transmission to humans and other animals.

Seasonal abundance of ticks collected at US Army Garrison Humphreys, Pyeongtaek, Republic of Korea, 2019–2021

Tick surveillance was conducted annually from February–November 2019–2021 at US Army Garrison (USAG) Humphreys, Pyeongtaek, Republic of Korea (ROK). Three general habitats, cut grasses, uncut grasses + herbaceous vegetation, and young mixed (deciduous and conifer) forest groves, were surveyed using tick drags. Ticks also were collected from Korean water deer, Hydropotes inermis argyropus, killed by vehicles at USAG Humphreys. A total of 53,428 ticks (18,004, 16,921, and 18,503 during 2019–2021, respectively) belonging to two genera and five species were collected by tick drag. Haemaphysalis longicornis (48,880; 91.49%) was the most frequently collected tick, followed by H. flava (2,501; 4.68%), Ixodes nipponensis (2,019; 3.78%), H. phasiana (27; 0.05%), and H. japonica (1; &lt;0.01%). A total of 1,340 ticks belonging to two genera and three species were collected from 20/27 (74.07%) Korean water deer from January–December 2019–2021. Haemaphysalis longicornis (1,138; 84.93%) was the most commonly collected tick, followed by I. nipponensis (184; 13.73%), and H. flava (18; 1.34%). Ixodes nipponensis was collected from Korean water deer throughout the year, indicating that they were active during all seasons in the ROK. Haemaphysalis longicornis adults and nymphs were collected similarly from all habitats during March-November. Haemaphysalis flava was more frequently collected during the early and late seasons when there were relatively low temperatures. Unlike other species, I. nipponensis was collected more frequently in mixed forests from March-June. Adult male H. longicornis accounted for only 0.05% (3♂/5,769♀) of the total number of adults collected by tick drag, while no males (0♂/194♀) were collected from Korean water deer. In contrast, only H. flava males (15) were collected from Korean water deer, while both sexes of I. nipponensis (103♂/75♀) were collected during 2019–2021.

Phylogeographic dynamics of the arthropod vector, the blacklegged tick (Ixodes scapularis)

BackgroundThe emergence of vector-borne pathogens in novel geographic areas is regulated by the migration of their arthropod vectors. Blacklegged ticks (Ixodes scapularis) and the pathogens they vector, including the causative agents of Lyme disease, babesiosis and anaplasmosis, continue to grow in their population sizes and to expand in geographic range. Migration of this vector over the previous decades has been implicated as the cause of the re-emergence of the most prevalent infectious diseases in North America.MethodsWe systematically collected ticks from across New York State (hereafter referred to as New York) from 2004 to 2017 as part of routine tick-borne pathogen surveillance in the state. This time frame corresponds with an increase in range and incidence of tick-borne diseases within New York. We randomly sampled ticks from this collection to explore the evolutionary history and population dynamics of I. scapularis. We sequenced the mitochondrial genomes of each tick to characterize their current and historical spatial genetic structure and population growth using phylogeographic methods.ResultsWe sequenced whole mitochondrial genomes from 277 ticks collected across New York between 2004 and 2017. We found evidence of population genetic structure at a broad geographic scale due to differences in the relative abundance, but not the composition, of haplotypes among sampled ticks. Ticks were often most closely related to ticks from the same and nearby collection sites. The data indicate that both short- and long-range migration events shape the population dynamics of blacklegged ticks in New York.ConclusionsWe detailed the population dynamics of the blacklegged tick (Ixodes scapularis) in New York during a time frame in which tick-borne diseases were increasing in range and incidence. Migration of ticks occurred at both coarse and fine scales in the recent past despite evidence of limits to gene flow. Past and current tick population dynamics have implications for further range expansion as habitat suitability for ticks changes due to global climate change. Analyses of mitochondrial genome sequencing data will expound upon previously identified drivers of tick presence and abundance as well as identify additional drivers. These data provide a foundation on which to generate testable hypotheses on the drivers of tick population dynamics occurring at finer scales.Graphical

Ecological correlates of ectoparasite load in a rodent: Complex roles of seasonality.

Understanding the mechanisms driving parasite distributions is not only important for understanding ecosystem functioning, but also crucial for disease control. Previous studies have documented the important roles of host sex, host body size, host behavioral trait (such as boldness and trappability), and seasonality in shaping parasite load. However, few studies have simultaneously assessed the roles of these factors, as well as their interactions. In spring and summer of 2021, we conducted live trapping in Hohhot, China, to collect ectoparasites on Daurian ground squirrel (Spermophilus dauricus), a small rodent widely distributed in East Asian grassland. We then used generalized linear models to explore the effects of several biological factors (sex, body weight, trappability, and reproductive status) and seasonality on the abundance of ticks and fleas in S. dauricus. Significant but inconsistent seasonal effects were observed: tick load was significantly greater in summer than in spring, while flea load was greater in spring than in summer. Seasons also significantly interacted with host trappability and body weight to affect tick abundance. Our results highlight the importance of considering seasonal changes in parasitism, as well as interactions between season and host biological traits in shaping parasite distributions.

Abundance of Ixodes ricinus Ticks (Acari: Ixodidae) and the Diversity of Borrelia Species in Northeastern Poland

Monitoring the abundance of ticks and the prevalence of pathogens in ticks is an important activity in assessing the risk of tick-borne diseases and helps to develop preventive measures. This study aimed to estimate the density of Ixodes ricinus, the prevalence of Borrelia species, and their diversity in northeastern Poland. The overall mean I. ricinus density was 9.7 ticks/100 m2. There were no differences between years, subregions, or habitats of study. The Borrelia infection rate was higher in females (22.6%) and males (14.3%) than in nymphs 5.5% (MIR). The most infected ticks came from the eastern subregion (10.1%) where the incidence of borreliosis among the inhabitants was over 20% higher than in the other subregions. In the infected ticks, B. afzelii (38.3%) and B. garinii (34.5%) were predominant. B. bavariensis was confirmed in I. ricinus in Poland for the first time. The most polymorphic was B. garinii. B. miyamotoi (belonged to the European type) was identified as a mono-infection in 0.9% of ticks and in 1.5% as a co-infection with B. afzelii and with B. garinii. Besides the risk of borreliosis and co-infections with different Borrelia species, physicians should also be aware of B. miyamotoi infections among patients.

Amblyomma ticks in animal carcasses hunted in Mapinguari National Park, Western Amazon, Brazil: New records on species and host-parasite relationships

Ticks are obligatory parasites and transmit several pathogens to animals and humans. This study aimed to report the parasitism of ticks on carcasses of animals hunted by hunters from communities near Mapinguari National Park, at the shared border of Amazonas and Rondonia states, northern Brazil. The ticks were collected from heads of carcasses of the following animals: South American tapir (Tapirus terrestris), collared peccary (Pecari tajacu) and long-nosed armadillo (Dasypus beniensis). Six Amblyomma tick species were identified: Amblyomma coelebs, Amblyomma naponense, Amblyomma latepunctatum, Amblyomma oblongoguttatum, Amblyomma scalpturatum, Amblyomma triste and Amblyomma spp. The most abundant tick species were A. oblongoguttatum and A. scalpturatum. DNA extraction and polymerase chain reaction (PCR) were performed on all ticks to test for the presence of rickettsial gltA gene fragments, but no amplification was observed. This study reports, for the first time, the parasitism of A. coelebs in the armadillo D. beniensis and the presence of A. triste in the states of Amazonas and Rondonia, updating the tick fauna to 24 and 39 species for these states, respectively.