Tick Stages Research Articles

Lake Michigan insights from island studies: the roles of chipmunks and coyotes in maintaining Ixodes scapularis and Borrelia burgdorferi in the absence of white-tailed deer

Deer management (e.g., reduction) has been proposed as a tool to reduce the acarological risk of Lyme disease. There have been few opportunities to investigate Ixodes scapularis (blacklegged tick) and Borrelia burgdorferi sensu stricto dynamics in the absence of white-tailed deer (Odocoileus virginianus) in midwestern North America. A pair of islands in Lake Michigan presented a unique opportunity to study the role of alternative hosts for the adult stage of the blacklegged tick for maintaining a tick population as a deer herd exists on North Manitou Island but not on South Manitou Island, where coyotes (Canis latrans) and hares (Lepus americanus) are the dominant medium mammals. Additionally, we were able to investigate the maintenance of I. scapularis and B. burgdorferi in small mammal communities on both islands, which were dominated by eastern chipmunks (Tamias striatus). From 2011 to 2015, we surveyed both islands for blacklegged ticks by drag cloth sampling, bird mist netting, and small and medium-sized mammal trapping. We assayed questing ticks, on-host ticks, and mammal biopsies for the Lyme disease pathogen, B. burgdorferi. We detected all three life stages of the blacklegged tick on both islands. Of the medium mammals sampled, no snowshoe hares (Lepus americanus, 0/23) were parasitized by adult blacklegged ticks, but 2/2 coyotes (Canis latrans) sampled on South Manitou Island in 2014 were parasitized by adult blacklegged ticks, suggesting that coyotes played a role in maintaining the tick population in the absence of deer. We also detected I. scapularis ticks on passerine birds from both islands, providing support that birds contribute to maintaining as well as introducing blacklegged ticks and B. burgdorferi to the islands. We observed higher questing adult and nymphal tick densities, and higher B. burgdorferi infection prevalence in small mammals and in adult ticks on the island with deer as compared to the deer-free island. On the islands, we also found that 25% more chipmunks were tick-infested than mice, fed more larvae and nymphs relative to their proportional abundance compared to mice, and thus may play a larger role compared to mice in the maintenance of B. burgdorferi. Our investigation demonstrated that alternative hosts could maintain a local population of blacklegged ticks and an enzootic cycle of the Lyme disease bacterium in the absence of white-tailed deer. Thus, alternative adult blacklegged tick hosts should be considered when investigating deer-targeted management tools for reducing tick-borne disease risk, especially when the alternative host community may be abundant and diverse.

Experimental infection and vector competence of Amblyomma patinoi, a member of the Amblyomma cajennense species complex, for the human pathogen Rickettsia rickettsii

Amblyomma patinoi ticks infected with Rickettsia rickettsii are present in Colombia, but its vector competence is unknown. Hence, we evaluated the vector competence of A. patinoi with R. rickettsii under laboratory conditions. Experimental guinea pigs and rabbits (males and females) were separated in the infected group (IG) and the control group (CG). In the IG, the filial 1 (F1) larvae (R. rickettsii-free) from Colombian A. patinoi engorged female specimens were exposed to R. rickettsii (ITU strain) by feeding on infected guinea pigs. Next, F1 nymphs and adults, and F2 larvae were allowed to feed on uninfected guinea pigs or rabbits and tested by qPCR targeting the gltA rickettsial gene. All animals used to feed the IG F1 ticks became febrile and had R. rickettsii infection (89% fatality rate) detected through serological or molecular techniques. After the F1 larvae ticks became R. rickettsii infected, subsequent IG tick stages were able to maintain the rickettsial infection by transstadial maintenance to all infested animals, indicating A. patinoi vector competence. Subsequently, almost 31% of the F1 female egg masses and only 42% of their F2 larvae were infected. Less than 50% of the infected females transmitted R. rickettsii transovarially, and only a part of the offspring were infected. This study demonstrated that A. patinoi might not be able to sustain R. rickettsii infection by transovarial transmission for successive tick generations without horizontal transmission via rickettsemic hosts. This condition might result in low R. rickettsii-infection rates of A. patinoi under natural conditions.

A Preliminary Study on the Abundance, Seasonality, and Sampling Patterns of Amblyomma americanum (Acari: Ixodidae) in Central Missouri

Amblyomma americanum (Ixodida: Ixodidae) is Missouri's most common tick species and a carrier of bacterial pathogens. The objectives of this study were to analyze tick abundance and seasonality in two locations in central Missouri, to compare the effectiveness of dragging and dry ice trap sampling methods for collecting A. americanum in the field, and to analyze tick developmental stage collection pattern. We collected ticks from Knob Noster State Park, in Johnson County, Missouri and Mark Twain National Forest, in Boone County, Missouri. On eight dates from May to November, we collected ticks simultaneously at both locations, using dry ice traps and drag sampling. Of the 7,475 collected ticks, 99.7% were A. americanum. We found the most larvae in August and September, the most nymphs in June and July, and the most adults in June. Drag sampling collected more nymphs at Columbia than Knob Noster on one sampling date in the late summer. Abundance did not differ between locations at any other time point, regardless of developmental stage or sampling method. Compared to the drag method, significantly more nymphs and adults were identified using the dry ice trap sampling method. Additionally, we found that nymphs and adults were more likely to be found in the same areas of the sampling locations, but neither larvae and adults nor nymphs and larvae followed this relationship. Our findings demonstrate a strong seasonality of A. americanum in Missouri and support dry ice trapping as an effective sampling method for collecting all of its life stages.

Tick infestation on medium\u2013large-sized mammalian hosts: are all equally suitable to Ixodes ricinus adults?

BackgroundIn Europe, the generalist tick, Ixodes ricinus, is the main vector of several tick-borne pathogens causing diseases in humans and livestock. Understanding how different species of hosts limit the tick population is crucial for management. In general, larger ectoparasites are expected to select hosts with larger body size. Consistent with this, larval and nymphal I. ricinus can feed on a wide range of different-sized vertebrates, while the adult female stage is expected to rely on a medium–large-sized host for reproduction. However, we still have a limited understanding of whether medium-sized hosts other than roe deer can serve as hosts to adult ticks, and other factors than size may also affect host selection.MethodsTo increase our understanding of the suitability of the different species of medium-sized hosts for adult ticks, we sampled mainly roadkill mammals from within the questing season of ticks. We counted life stages of ticks on roe deer (Capreolus capreolus) (n = 29), red fox (Vulpes vulpes) (n = 6), badger (Meles meles) (n = 14) and red squirrel (Sciurus vulgaris) (n = 17) from spatially overlapping populations in Norway, and analysed variation between species across different body parts with a mixed-effects negative binomial model (with and without zero-inflation).ResultsRed squirrel hosted a high density of larval and nymphal I. ricinus, but only one individual had adult female ticks. Roe deer hosted by far the largest number of adult ticks. Badgers had very few ticks, possibly due to their thick skin. Red foxes had intermediate numbers, but a high proportion of subcutaneous, dead ticks (69.3%), suggesting they are not very suitable hosts. Body mass predicted the presence of adult I. ricinus ticks. However, species was a better predictor than body mass for number of ticks, suggesting there was species variation in host suitability beyond body mass per se.ConclusionsOur study provides evidence that roe deer are indeed the main suitable reproduction host to adult I. ricinus ticks, and are likely a key to host limitation of the tick population in this northern ecosystem.Graphical

Acaricidal activity of Artemisia herba-alba and Melia azedarach oil nanoemulsion against Hyalomma dromedarii and their toxicity on Swiss albino mice.

Biopesticides such as essential oils (EOs) are considered an improvement for integrated pest control as they appear to be less toxic to the environment than chemical acaricides. The current study aimed to evaluate the acaricidal activity of Artemisia herba-alba and Melia azedarach oil loaded nano-emulsion as alternatives for chemical acaricides against the camel tick Hyalomma dromedarii, besides evaluating their toxic effect on Swiss albino mice. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used for the characterization of loaded nano-emulsions.The immersion test was used for the bioassay of both loaded nanoemulsions on tick stages (egg, nymph, larva, and adult). Mortality percentages and LC50 values of each tick stage were calculated. Reproductive performance for the survived engorged females after treatment was monitored. The toxicity of both loaded nano-emulsions was evaluated on Swiss albino mice by an oral dose of 1500mg/kg/day for five successive days. The hematological, biochemical, and histopathological changes were evaluated. TEM characterization revealed spherical droplets for A. herba-alba and M. azedarach oil loaded nano-emulsion with droplet size ranging from 62 to 69nm and 52-91nm, respectively. FTIR revealed the absence of extra peaks in the loaded nano-emulsions that confirmed no chemical changes existed by ultrasonication. The LC50 values of A. herba-alba and M. azedarach oil loaded nano-emulsion on embryonated eggs, larvae, engorged nymphs, and unfed adults were 0.3 and 1.1%, 0.7 and 1.7%, 0.3 and 0.4%, 4.4 and 22.2%, respectively. The egg productive index (EPI), egg number, and hatchability percentage were lower in the treated females compared with Butox 5% (deltamethrin) and control. The hematological picture and biochemical analysis revealed insignificant changes in the treatment group compared with the negative control group. The liver of the A. herba-alba and M. azedarach oil loaded nano-emulsion treated group exhibited vacuolar degeneration and infiltration of lymphocytic cells. The kidney of mice treated with A. herba-alba and M. azedarach oil loaded nano-emulsion showed hemolysis and slight degeneration of epithelial cells of tubules. It is concluded that A. herba-alba and M. azedarach oil loaded nano-emulsion have good acaricidal activity against camel tick H. dromedarii.

Seasonal dynamics of Amblyomma sculptum in two areas of the Cerrado biome midwestern Brazil, where human cases of rickettsiosis have been reported.

Amblyomma sculptum is a common human-biting tick in Brazil, where it plays an important role as a vector of Rickettsia rickettsii, the agent of the Brazilian spotted fever. Herein, we studied the seasonal dynamics of A. sculptum in an urban area of the Cerrado biome in midwestern Brazil, where human rickettsiosis is endemic. Ticks were collected in two sites located within the campus of Federal University of Goiás. The collections were done by dragging, flagging and visual search. In total, 117,685 ticks were collected, including 100,627 Amblyomma spp. larvae, 10,055 nymphs and 6977 adults of A. sculptum, and one nymph and 25 adults of Amblyomma dubitatum. The highest peak of larvae occurred in June 2018 and in July 2019, whereas nymphs peaked in July 2018 and September 2019. Adults reached their highest numbers in March 2018 and November 2019. These data suggest that A. sculptum develops one generation per year in this urban area of the Cerrado biome in midwestern Brazil. Interestingly, the peak of nymphs occurred during the same period of all confirmed cases of rickettsiosis in Goiás, suggesting a possible relationship between the seasonal dynamics of this tick stage and rickettsiosis transmission in this state.

Molecular detection of Rickettsia raoultii, Rickettsia tamurae, and associated pathogens from ticks parasitizing water deer (Hydropotes inermis argyropus) in South Korea

Most defined Rickettsiales, which can be transmitted by ticks, are known to be important zoonotic pathogens. Some of these pathogens can cause severe diseases in humans, including anaplasmosis, rickettsioses, and ehrlichiosis. Previous studies in South Korea have investigated tick-borne pathogens (TBPs) residing in ticks found on grassy vegetation and animals. However, there is limited phylogenetic information on TBPs in ticks parasitizing Korean water deer (KWD; Hydropotes inermis argyropus). This study evaluated the prevalence, risk factors (regions, tick stages, and tick species), and coinfections of TBPs in ticks parasitizing KWD. Were collected a total of 283 hard ticks, including Haemaphysalis longicornis, Haemaphysalis flava, and Ixodes nipponensis from KWD in South Korea from 2013 to 2017. In 173 tested tick pools, genes for seven TBPs, namely Rickettsia raoultii (20 %), Rickettsia tamurae (1 %), Candidatus Rickettsia longicornii (31 %), Ehrlichia canis (3 %), Anaplasma capra (3 %), Anaplasma bovis (2 %), and Anaplasma sp. (1 %), were detected. The unidentified Anaplasma sp. isolates revealed a 98.4 %–99.3 % sequence identity with Anaplasma sp. in GenBank sequences obtained from ticks. To the best of our knowledge, this is the first study to report the presence of the emerging human pathogen R. tamurae in South Korea. These results should increase awareness about the need for continued development of epidemiological control measures, and medical and veterinary communities must be informed of their high infection potential and clinical complexity in humans.

Detailed Infestation Spectrums About Biological Stages of Hard Ticks (Acari: Ixodida: Ixodidae) in Humans: A Systematic Review and Meta-Analysis.

A comprehensive systematic meta-analysis review which deals with the degrees and trends of human infestation by biological stages of ticks, the degrees and trends of human infestation by biological stages of ticks in rural and urban areas, the infestation scale of tick attachment sites in body parts of humans, and the degrees of tick infestation in human age groups is critical. Therefore, this systematic meta-analysis review summarizes the above-detailed human infestation spectrums about biological stages of hard ticks. After a preliminary review from 605 papers representing areas of the study objectives, 96 were selected for detailed human infestation spectrums of biological stages of hard ticks. In general, the results suggest that the adult ticks, and mostly females attack humans more than larval and nymphalid ones, and adult males, respectively. Unlike the trends of human infestation by larval and nymphalid stages of ticks, and the adult, male and female ticks which exhibited approximately a sharply decreasing trend, the global trend of human infestation by hard ticks exhibited approximately a sharply increasing trend over time. Ticks attack humans more in rural area than urban area. Also, the trends of human tick infestation in rural and urban areas exhibit, respectively, a sharp increase and decrease trends over time. The majority of ticks mostly attach to human body trunk and extremity than head and neck, and genital area. Ticks attack human age groups of 0-9, 20-39, and 40-59years more than those aged between 10 and 19 or older than 60years.

In vitro acaricidal activity of green synthesized nickel oxide nanoparticles against the camel tick, Hyalomma dromedarii (Ixodidae), and its toxicity on Swiss albino mice

The green synthesized nanoparticles have been determined as a novel pesticide against arthropod pests. This study was designed to evaluate the in vitro acaricidal activity of green synthesized nickel oxide nanoparticles (NiO NPs) using aqueous extract of Melia azedarach ripened fruits against different developmental stages of the camel tick Hyalomma dromedarii in addition to their toxic effect on laboratory animals. The synthesized NiO NPs were characterized by UV-visible (UV-Vis) spectroscopy, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The UV-Vis spectra of the NiO NPs showed an absorption peak at 307nm. FTIR analysis showed the possible functional groups used for capping and stabilization of NiO NPs with strong bands at 3416.2 and 1626.6cm-1. The SEM images of the NiO NPs exhibited a size ranging from 21 to 35nm. The immersion test was used for the in vitro application of the synthesized NiO NPs on the various tick stages (egg, nymph, larva, and adult). Mortality percentages and LC50 values of each tick stage were calculated. The oviposition and hatchability of the engorged females were monitored for the survived tick after treatment. The LC50 values for NiO NPs on embryonated eggs, larvae, and engorged nymphs were 5.00, 7.15, and 1.90mg/mL, respectively. The egg productive index (EPI), egg number, and hatchability (%) were lower in females treated with the NiO NPs than in control ticks. The toxicity of the NiO NPs on laboratory animals was also investigated using Swiss albino mice by oral dose of 500mg/kg/day administration for five consecutive days. The hematological, biochemical, and histopathological changes were evaluated. The hematological analysis showed significant increase in the level of white blood cells (WBC) and hemoglobin (Hb). Biochemical analysis showed non-significant decrease in alkaline phosphatase (ALP) and alanine amino transferase (ALT). We concluded that NiO NPs have a significant acaricidal activity as demonstrated on eggs, larvae, engorged nymphs, and fully fed females of H. dromedarii. From a toxicological point of view further in vivo investigations are needed to determine the mechanism of toxic effect of NiO NPs.

Lockdown effect of the brown dog tick with-in a bamboo sticky trap using sustained release pheromone beads in kennels

ABSTRACT Ticks are ubiquitous in nature and have considerable medical and veterinary importance. They act as vectors for a diverse array of pathogens affecting animals and humans. Rhipicephalus sanguineus is the most prevalent species infesting the dogs in Tamil Nadu. Control of this three-host tick mainly depends on the use of acaricides, with attendant problems of development of acaricidal resistance in ticks and possibility of drug residues. In the current study, pheromones were evaluated as an alternative substance for control of the dog tick. Optimal concentration of attractant sex pheromone (ASP), assembly pheromone (AP), and combination of both ASP and AP were encapsulated using calcium alginate beads for sustained release of pheromones. Bamboo sticky traps were designed as a platform to hold these pheromone encapsulated beads. Field trials were conducted using these pheromone lures as bait in the bamboo trap. Field trials revealed that AP encapsulated calcium alginate beads lured the maximum number of different stages of dog ticks. Thus, a bamboo trap with AP encapsulated calcium alginate beads can be used in integrated pest management along with other routine practices for control of dog tick in kennels. Statistical analysis by chi-square test revealed that there was a highly significant (p < 0.01) difference in the level of attraction between engorged and questing stages of ticks to the pheromones in the trap.

Challenges in Tick-Borne Pathogen Detection: The Case for Babesia spp. Identification in the Tick Vector.

The causative agents of Babesiosis are intraerythrocytic protozoa of the genus Babesia. Babesia parasites are present around the world, affecting several mammals including humans, pets and livestock, hence its medical and veterinary relevance. Babesia spp. detection in its invertebrate host is a main point in understanding the biology of the parasite to acquire more knowledge on the host–Babesia–vector interactions, as increasing knowledge of the Babesia lifecycle and babesiosis epidemiology can help prevent babesiosis outbreaks in susceptible mammals. The aim of the present review is to highlight the newest findings in this field, based on a bibliographic compilation of research studies recently carried out for the detection of the main Babesia species found in tick vectors affecting mammalian hosts, including the different tick stages such as adult ticks, larvae, nymphs and eggs, as well as the detection method implemented: microscopic tools for parasite identification and molecular tools for parasite DNA detection by conventional PCR, nested-PCR, PCR-RFLP, PCR-RLB hybridization, real time-PCR, LAMP and RAP assays. Although molecular identification of Babesia parasites has been achieved in several tick species and tissue samples, it is still necessary to carry out transmission experiments through biological models to confirm the vectorial capacity of various tick species.

Solar tick trap with a pheromone lure – A stand-in approach for off-host control of Rhipicephalus sanguineus sensu lato ticks

Rhipicephalus sanguineus sensu lato (s.l.), the brown dog tick, transmits several important haemo-protozoan and rickettsial pathogens to dogs. Effective control of these ticks is entirely by the use of acaricidal preparations both on and off the host. Indiscriminate use of acaricides can cause environmental pollution and toxicity to humans as well as development of acaricidal resistance in ticks. As an alternative control strategy, a novel, eco-friendly and economical solar tick trap, which attracts ticks using pheromones and kills them by electrocution, was fabricated for use in kennels to control different stages of ticks. All stages of ticks were found to be lured to sex pheromone (SP), assembly pheromone (AP) and a combination of SP + AP impregnated vapour patches and electrocuted. There was a highly significant (p < 0.01) difference in the level of attraction between engorged and questing stages of ticks to the pheromones in the trap. AP lured a higher number of ticks, both engorged and questing, in comparison to other pheromones. The solar tick trap bearing vapour patch impregnated with AP was considered most suitable for use in integrated pest management (IPM) of ticks in heavily infested kennels. The solar trap remained effective for a month after which, replacement of pheromone impregnated vapour patch was necessary for continued and effective attraction of the ticks. This solar tick trap device, which uses pheromone without any acaricide, could prove to be an ideal green alternative for use in IPM of ticks in kennels.

N-Glycosylation in Piroplasmids: Diversity within Simplicity.

N-glycosylation has remained mostly unexplored in Piroplasmida, an order of tick-transmitted pathogens of veterinary and medical relevance. Analysis of 11 piroplasmid genomes revealed three distinct scenarios regarding N-glycosylation: Babesia sensu stricto (s.s.) species add one or two N-acetylglucosamine (NAcGlc) molecules to proteins; Theileria equi and Cytauxzoon felis add (NAcGlc)2-mannose, while B. microti and Theileria s.s. synthesize dolichol-P-P-NAcGlc and dolichol-P-P-(NAcGlc)2 without subsequent transfer to proteins. All piroplasmids possess the gene complement needed for the synthesis of the N-glycosylation substrates, dolichol-P and sugar nucleotides. The oligosaccharyl transferase of Babesia species, T. equi and C. felis, is predicted to be composed of only two subunits, STT3 and Ost1. Occurrence of short N-glycans in B. bovis merozoites was experimentally demonstrated by fluorescence microscopy using a NAcGlc-specific lectin. In vitro growth of B. bovis was significantly impaired by tunicamycin, an inhibitor of N-glycosylation, indicating a relevant role for N-glycosylation in this pathogen. Finally, genes coding for N-glycosylation enzymes and substrate biosynthesis are transcribed in B. bovis blood and tick stages, suggesting that this pathway is biologically relevant throughout the parasite life cycle. Elucidation of the role/s exerted by N-glycans will increase our understanding of these successful parasites, for which improved control measures are needed.

A framework for signaling throughout the life cycle of Babesia species.

Babesia species are tick-borne intracellular parasites that infect the red blood cells of their mammalian host, leading to severe or fatal disease. Babesia spp. infect a wide range of mammalian species and cause a significant economic burden globally, predominantly through disease in cattle. Several Babesia spp. are increasingly being recognized as zoonotic pathogens of humans. Babesia spp. have complex life cycles involving multiple stages in the tick and the mammalian host. The parasite utilizes complex signaling pathways during replication, egress, and invasion in each of these stages. They must also rapidly respond to their environment when switching between the mammalian and tick stages. This review will focus on the signaling pathways and environmental stimuli that Babesia spp. utilize in the bloodstream and for transmission to the tick, with an emphasis on the role of phosphorylation- and calcium-based signaling during egress and invasion. The expanding availability of in vitro and in vivo culture systems, genomes, transcriptomes, and transgenic systems available for a range of Babesia spp. should encourage further biological and translational studies of these ubiquitous parasites.

Comparative effectiveness of acaricides

The use of chemicals is the main method of controlling ectoparasites around the world. In Ukraine, due to the lack of an effective system for controlling ixodid ticks, there is an annual increase in the number of tick-borne diseases. Prevention of tick bites is largely based on the use of chemical repellents and acaricides. The study was conducted in 2019 in the laboratory of parasitology of the Department of Infectious and Invasive Diseases FVMTT PDATU. The experiments used neonicotinoids – imidacloprid, phenyl pyrazole - fipronil, pyrethroid compounds – cyfluthrin, permethrin. In the first phase of the studies, acetone was used as a diluent, each acaricide was diluted to obtain a 1.0 % solution, after which 10-fold dilutions of each acaricide from 1:10 to 1:107 were prepared and the study was performed. In the second stage of research, the method of topical application of acetone solutions of different concentrations was used. Cyfluthrin caused 100 % death of ticks of D. reticulatus and I. ricinus within 24 hours at a dilution of up to 1:10.000. Statistical analysis showed that ticks of the two species were significantly more sensitive to cyfluthrin and permethrin than to fipronil and imidacloprid, based on LD50 values. According to the level of contact activity, which is determined by topical application and the estimated LD50, cyfluthrin against I. ricinus was the most active acaricide and LD50 was 0.33 ± 0.07. In relation to D. reticulatus, the LD50 of cyfluthrin was 0.51 ± 0.08. After contact with cyfluthrin, 40 % of I. ricinus ticks and 30 % of D. reticulatus ticks died within one hour, and after 24 hours all ticks were dead. Among the adult stages of ixodid ticks, males were more resistant to the drugs than females. Therefore, cyfluthrin is recommended for the controling of ticks, which ensures the death of mites after a short period of time.

A Novel Arthropod Host of Brucellosis in the Arid Steppe Ecosystem.

Brucellosis is a severe public health problem in the Inner Mongolia regions of China. The recent prevalence of brucellosis outbreaks may be attributed to an increase in the activity of ticks and other air-borne vectors. Dermacentor nuttalli (D. nuttalli) is a native tick species of Inner Mongolia; similar to other tick species, D. nuttalli carries a variety of pathogens that can be transmitted to a wide range of animals. In this study, we have investigated the potential of D. nuttalli in transmitting brucellosis. From 2015 to 2019, 2,256 ticks were collected from 23 different pastoral areas of Hulun Buir. Brucellosis pathogen was detected using DNA extracted from different developmental stages of ticks. Salivary gland and midgut tissue samples were used as templates to amplify Brucella Bscp31 gene (Brucella genus-specific gene) by using TaqMan Real-Time polymerase chain reaction (PCR). To detect the presence of Bscp31 protein, which is specific to Brucella spp., in the midgut and salivary gland tissues of D. nuttalli, Western blotting and immunofluorescence were performed. Additionally, Brucella spp. were isolated using a culture medium. Tick samples were identified as D. nuttalli. Different percentages of Brucella genus-specific genes could be found in the tick samples. From 2015 to 2019, the positivity rate for the detection of Bscp31 gene in D. nuttalli ranged from 0.00 to 87.80%, with the highest rate of 89.00%. In addition, Brucella genus-specific genes were successfully detected in the samples isolated from all the developmental stages and anatomical regions of ticks. Bscp31 protein was present in the midgut and salivary gland of D. nuttalli. Further, B. melitensis biotype 3 was isolated from eggs and engorged adults of D. nuttalli. These findings demonstrate that D. nuttalli is a potent, long-term carrier of Brucella spp. that can exhibit transovarial transmission potential, presenting D. nuttalli as a novel arthropod host for Brucella spp. This study, therefore, indicates the potential risk of transmission of brucellosis via tick bites among animals as well as human beings.

Comparative analysis of gene expression between Babesia bovis blood stages and kinetes allowed by improved genome annotation

Throughout their life cycle, Babesia parasites alternate between a mammalian host, where they cause babesiosis, and the tick vector. Transition between hosts results in distinct environmental signals that influence patterns of gene expression, consistent with the morphological and functional changes operating in the parasites during their life stages. In addition, comparing differential patterns of gene expression among mammalian and tick parasite stages can provide clues for developing improved methods of control. Hereby, we upgraded the genome assembly of Babesia bovis, a bovine hemoparasite, closing a 139 kbp gap, and used RNA-Seq datasets derived from mammalian blood and tick kinete stages to update the genome annotation. Of the originally annotated genes, 1,254 required structural changes, and 326 new genes were identified, leading to a different predicted proteome compared to the original annotation. Next, the RNA-Seq data was used to identify B. bovis genes that were differentially expressed in the vertebrate and arthropod hosts. In blood stages, 28% of the genes were upregulated up to 300 fold, whereas 26% of the genes in kinetes, a tick stage, were upregulated up to >19,000 fold. We thus discovered differentially expressed genes that may play key biological roles and serve as suitable targets for the development of vaccines to control bovine babesiosis.

Targeting the Exoskeleton Elementome to Track Tick Geographic Origins.

Understanding the origin of ticks is essential for evaluating the risk of tick-borne disease introduction into new territories. However, when collecting engorged ticks from a host, it is virtually impossible to identify the geographical location where this tick was acquired. Recently, the elementome of tick exoskeleton was characterized by using scanning electron microscopy (SEM) and energy dispersive spectroscopy analysis (EDS). The objective of our preliminary proof-of-concept study was to evaluate the use of SEM-EDS for the analysis of tick exoskeleton elementome to gain insight into the tick geographic and host origin. For this preliminary analysis we used 10 samples of engorged ticks (larvae and nymphs of six species from three genera) collected from various resident hosts and locations. The elementome of the tick exoskeleton was characterized in dorsal and ventral parts with three scans on each part using an EDS 80 mm2 detector at 15 kV in a field emission scanning electron microscope. We used principal component analysis (PCA) (varimax rotation) to reduce the redundancy of data under the premise of losing information as little as possible. The PCA was used to test whether the different variables (tick species, stages, hosts, or geographic locations) differ in the composition of exoskeleton elementome (C, O, P, Cl, and Na). Analyses were carried out using SPSS. The PCA analysis explained a high percentage of variance using the first two factors, C and O (86.13%). The first PC (PC-1; 63.12%) was positively related to P, Cl, and Na, and negatively related to C. The second principal component (23.01%) was mainly positively related to C. In the space defined by the two extracted PC (PC-1 and PC-2), the elementome of tick samples was clearly associated with tick species, but not with developmental stages, hosts or geographic locations. A differentiated elementome pattern was observed within Romanian regions (CJ and TL) for the same tick species. The use of the SEM-EDS methodological approach provided additional information about the tick exoskeleton elementome with possible applications to the identification of tick origin host and location.

Temporal analysis of the bovine lymph node transcriptome during cattle tick (Rhipicephalus microplus) infestation

Livestock production is a fundamental source of revenue and nutrition, wherein cattle-farming constitutes one of the major agricultural industries. Vectors and vector-borne diseases constitute one of the major factors that decrease the livelihood of all farming communities, more so in resource-poor communities and developing countries. Understanding the immunological responses during tick infestation in cattle is instrumental in the development of novel and improved tick control strategies, such as vaccines. In this study, gene expression patterns were compared within the lymph nodes of three cattle breeds at different life stages of the cattle tick, Rhipicephalus microplus. For Bonsmara (5/8Bos taurus indicus × 3/8B. t. taurus) cattle specifically, some 183 genes were found to be differentially expressed within the lymph nodes during larval and adult tick feeding, relative to uninfested cattle. Overall, the data provides evidence for a transcriptional regulatory network that is activated during immature tick infestation, but is down-regulated towards basal transcriptional levels when adult ticks are feeding. Specific processes in the lymph nodes of Bonsmara cattle were found to be differentially regulated on a transcriptional level. These include: (1) Leukocyte recruitment to the lymph node via chemokines and chemotaxis, (2) Trans-endothelial and intranodal movement on the reticular network, (3) Active regulation of cellular transcription and translation in the lymph node (including leukocyte associated cellular regulatory networks) and (4) Chemokine receptors regulating the movement of cells out of the lymph node. This work provides a first transcriptome analysis of bovine lymph node responses in tick-infested cattle. Findings show a dynamic immune response to tick infestation for the Bonsmara cattle breed, and that suppression of the maturation of the cattle hosts' immunity is especially evident during the larval feeding stages.

Survey of Rickettsia parkeri and Amblyomma maculatum associated with small mammals in southeastern Virginia

Small mammals are often parasitized by the immature stages of hard-bodied ticks (family Ixodidae) and may serve as reservoir hosts of tick-borne pathogens. Amblyomma maculatum, the Gulf Coast tick, is the primary vector of Rickettsia parkeri, the causative agent of R. parkeri rickettsiosis. This hard-bodied tick species is expanding its historical range from the Gulf Coast of the U.S. up the Mid-Atlantic coast. In Mid-Atlantic states, such as Virginia, R. parkeri prevalence is higher in these ticks than those found in its historical range. This high prevalence may be explained in part by small mammal populations. In this study, small mammals were trapped and checked for the presence of immature A. maculatum. The ticks as well as tissue samples from these mammals were tested for the presence of R. parkeri. This study found six rodent species acting as hosts to immature A. maculatum and three species that may play a role in the enzootic cycle of R. parkeri in Virginia.